Hello,
I’m trying to implement SSH Hostbased Authentication between IPA joined machines but I’m with difficulties regarding:
* The /etc/ssh/ssh_known_hosts file.
In a FreeIPA environment the known_hosts are stored on IPA, and I’m aware of the ProxyCommand /usr/bin/sss_ssh_knownhostsproxy; but how can I create this file with the entries from FreeIPA?
* Another issue is with the /etc/ssh/shosts.equiv file.
It supports plain hostnames or netgroups, which is a NIS thing. FreeIPA offers any netgroups compatibility? I’m expecting to put something like: @nodes on this file to keep it simple. Any changes on IPA hosts would be reflected automatically.
Thanks,
PS: Further documentation about SSH Hostbased Authentication: https://en.wikibooks.org/wiki/OpenSSH/Cookbook/Host-based_Authentication
Vinícius Ferrão via FreeIPA-users wrote:
Hello,
I’m trying to implement SSH Hostbased Authentication between IPA joined machines but I’m with difficulties regarding:
The /etc/ssh/ssh_known_hosts file.
In a FreeIPA environment the known_hosts are stored on IPA, and I’m aware of the ProxyCommand /usr/bin/sss_ssh_knownhostsproxy; but how can I create this file with the entries from FreeIPA?
Why do you want to? That is the point of the proxy, so dynamic files don't need to be maintained.
Another issue is with the /etc/ssh/shosts.equiv file.
It supports plain hostnames or netgroups, which is a NIS thing. FreeIPA offers any netgroups compatibility? I’m expecting to put something like: @nodes on this file to keep it simple. Any changes on IPA hosts would be reflected automatically.
IPA hostgroups are automatically mirrored as netgroups.
rob
Hi Rob
On 15 Oct 2019, at 10:22, Rob Crittenden <rcritten@redhat.commailto:rcritten@redhat.com> wrote:
Vinícius Ferrão via FreeIPA-users wrote: Hello,
I’m trying to implement SSH Hostbased Authentication between IPA joined machines but I’m with difficulties regarding:
* The /etc/ssh/ssh_known_hosts file.
In a FreeIPA environment the known_hosts are stored on IPA, and I’m aware of the ProxyCommand /usr/bin/sss_ssh_knownhostsproxy; but how can I create this file with the entries from FreeIPA?
Why do you want to? That is the point of the proxy, so dynamic files don't need to be maintained.
Because it appears to be a requirement. Unfortunately SSH does not look at /var/lib/sss/pubconf/known_hosts:
debug1: userauth_hostbased: cuser admin chost hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br. pkalg ecdsa-sha2-nistp256 slen 100 [preauth] debug3: mm_key_allowed entering [preauth] debug3: mm_request_send entering: type 22 [preauth] debug3: mm_key_allowed: waiting for MONITOR_ANS_KEYALLOWED [preauth] debug3: mm_request_receive_expect entering: type 23 [preauth] debug3: mm_request_receive entering [preauth] debug3: mm_request_receive entering debug3: monitor_read: checking request 22 debug3: mm_answer_keyallowed entering debug3: mm_answer_keyallowed: key_from_blob: 0x561842345040 debug2: hostbased_key_allowed: chost hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br. resolvedname hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br ipaddr 172.26.0.1 debug2: stripping trailing dot from chost hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br. debug2: auth_rhosts2: clientuser admin hostname hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br ipaddr 172.26.0.1 debug1: temporarily_use_uid: 1683000000/1683000000 (e=0/0) debug1: restore_uid: 0/0 debug1: fd 8 clearing O_NONBLOCK debug2: hostbased_key_allowed: access allowed by auth_rhosts2 debug1: temporarily_use_uid: 1683000000/1683000000 (e=0/0) debug1: restore_uid: 0/0 debug1: check_key_in_hostfiles: key for host hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br not found debug1: temporarily_use_uid: 1683000000/1683000000 (e=0/0) debug1: restore_uid: 0/0 debug1: check_key_in_hostfiles: key for host hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br not found debug3: mm_answer_keyallowed: key 0x561842345040 is not allowed Failed hostbased for admin from 172.26.0.1 port 55634 ssh2: ECDSA SHA256:wJ0OVmkiVnMjuoiRe5sdBVz5sMTTKIbYRWorTk+CnUQ, client user "admin", client host "hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br”
If you look at the sshd log there is this: debug1: check_key_in_hostfiles: key for host hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br not found
But if I create the file manually it will work:
debug1: check_key_in_hostfiles: key for hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br found at /etc/ssh/ssh_known_hosts:1
Any ideias?
* Another issue is with the /etc/ssh/shosts.equiv file.
It supports plain hostnames or netgroups, which is a NIS thing. FreeIPA offers any netgroups compatibility? I’m expecting to put something like: @nodes on this file to keep it simple. Any changes on IPA hosts would be reflected automatically.
IPA hostgroups are automatically mirrored as netgroups.
Nice, this worked flawlessly!!!
rob
Thank you very much.
V.
Vinícius Ferrão wrote:
Hi Rob
On 15 Oct 2019, at 10:22, Rob Crittenden <rcritten@redhat.com mailto:rcritten@redhat.com> wrote:
Vinícius Ferrão via FreeIPA-users wrote:
Hello,
I’m trying to implement SSH Hostbased Authentication between IPA joined machines but I’m with difficulties regarding:
- The /etc/ssh/ssh_known_hosts file.
In a FreeIPA environment the known_hosts are stored on IPA, and I’m aware of the ProxyCommand /usr/bin/sss_ssh_knownhostsproxy; but how can I create this file with the entries from FreeIPA?
Why do you want to? That is the point of the proxy, so dynamic files don't need to be maintained.
Because it appears to be a requirement. Unfortunately SSH does not look at /var/lib/sss/pubconf/known_hosts:
debug1: userauth_hostbased: cuser admin chost hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br. pkalg ecdsa-sha2-nistp256 slen 100 [preauth] debug3: mm_key_allowed entering [preauth] debug3: mm_request_send entering: type 22 [preauth] debug3: mm_key_allowed: waiting for MONITOR_ANS_KEYALLOWED [preauth] debug3: mm_request_receive_expect entering: type 23 [preauth] debug3: mm_request_receive entering [preauth] debug3: mm_request_receive entering debug3: monitor_read: checking request 22 debug3: mm_answer_keyallowed entering debug3: mm_answer_keyallowed: key_from_blob: 0x561842345040 debug2: hostbased_key_allowed: chost hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br. resolvedname hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br ipaddr 172.26.0.1 debug2: stripping trailing dot from chost hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br. debug2: auth_rhosts2: clientuser admin hostname hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br ipaddr 172.26.0.1 debug1: temporarily_use_uid: 1683000000/1683000000 (e=0/0) debug1: restore_uid: 0/0 debug1: fd 8 clearing O_NONBLOCK debug2: hostbased_key_allowed: access allowed by auth_rhosts2 debug1: temporarily_use_uid: 1683000000/1683000000 (e=0/0) debug1: restore_uid: 0/0 debug1: check_key_in_hostfiles: key for host hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br not found debug1: temporarily_use_uid: 1683000000/1683000000 (e=0/0) debug1: restore_uid: 0/0 debug1: check_key_in_hostfiles: key for host hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br not found debug3: mm_answer_keyallowed: key 0x561842345040 is not allowed Failed hostbased for admin from 172.26.0.1 port 55634 ssh2: ECDSA SHA256:wJ0OVmkiVnMjuoiRe5sdBVz5sMTTKIbYRWorTk+CnUQ, client user "admin", client host "hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br”
It does for me:
debug3: hostkeys_foreach: reading file "/root/.ssh/known_hosts" debug3: hostkeys_foreach: reading file "/var/lib/sss/pubconf/known_hosts" debug3: record_hostkey: found key type ED25519 in file /var/lib/sss/pubconf/known_hosts:2 debug3: record_hostkey: found key type RSA in file /var/lib/sss/pubconf/known_hosts:4 debug3: record_hostkey: found key type ECDSA in file /var/lib/sss/pubconf/known_hosts:6
The client only pushes the SSHFP records on enrollment if IPA is serving DNS.
rob
If you look at the sshd log there is this: debug1: check_key_in_hostfiles: key for host hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br not found
But if I create the file manually it will work:
debug1: check_key_in_hostfiles: key for hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br found at /etc/ssh/ssh_known_hosts:1
Any ideias?
- Another issue is with the /etc/ssh/shosts.equiv file.
It supports plain hostnames or netgroups, which is a NIS thing. FreeIPA offers any netgroups compatibility? I’m expecting to put something like: @nodes on this file to keep it simple. Any changes on IPA hosts would be reflected automatically.
IPA hostgroups are automatically mirrored as netgroups.
Nice, this worked flawlessly!!!
rob
Thank you very much.
V.
On 15 Oct 2019, at 17:49, Rob Crittenden <rcritten@redhat.commailto:rcritten@redhat.com> wrote:
Vinícius Ferrão wrote: Hi Rob
On 15 Oct 2019, at 10:22, Rob Crittenden <rcritten@redhat.commailto:rcritten@redhat.com mailto:rcritten@redhat.com> wrote:
Vinícius Ferrão via FreeIPA-users wrote: Hello,
I’m trying to implement SSH Hostbased Authentication between IPA joined machines but I’m with difficulties regarding:
* The /etc/ssh/ssh_known_hosts file.
In a FreeIPA environment the known_hosts are stored on IPA, and I’m aware of the ProxyCommand /usr/bin/sss_ssh_knownhostsproxy; but how can I create this file with the entries from FreeIPA?
Why do you want to? That is the point of the proxy, so dynamic files don't need to be maintained.
Because it appears to be a requirement. Unfortunately SSH does not look at /var/lib/sss/pubconf/known_hosts:
debug1: userauth_hostbased: cuser admin chost hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br. pkalg ecdsa-sha2-nistp256 slen 100 [preauth] debug3: mm_key_allowed entering [preauth] debug3: mm_request_send entering: type 22 [preauth] debug3: mm_key_allowed: waiting for MONITOR_ANS_KEYALLOWED [preauth] debug3: mm_request_receive_expect entering: type 23 [preauth] debug3: mm_request_receive entering [preauth] debug3: mm_request_receive entering debug3: monitor_read: checking request 22 debug3: mm_answer_keyallowed entering debug3: mm_answer_keyallowed: key_from_blob: 0x561842345040 debug2: hostbased_key_allowed: chost hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br. resolvedname hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br ipaddr 172.26.0.1 debug2: stripping trailing dot from chost hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br. debug2: auth_rhosts2: clientuser admin hostname hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br ipaddr 172.26.0.1 debug1: temporarily_use_uid: 1683000000/1683000000 (e=0/0) debug1: restore_uid: 0/0 debug1: fd 8 clearing O_NONBLOCK debug2: hostbased_key_allowed: access allowed by auth_rhosts2 debug1: temporarily_use_uid: 1683000000/1683000000 (e=0/0) debug1: restore_uid: 0/0 debug1: check_key_in_hostfiles: key for host hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br not found debug1: temporarily_use_uid: 1683000000/1683000000 (e=0/0) debug1: restore_uid: 0/0 debug1: check_key_in_hostfiles: key for host hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br not found debug3: mm_answer_keyallowed: key 0x561842345040 is not allowed Failed hostbased for admin from 172.26.0.1 port 55634 ssh2: ECDSA SHA256:wJ0OVmkiVnMjuoiRe5sdBVz5sMTTKIbYRWorTk+CnUQ, client user "admin", client host "hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br”
It does for me:
debug3: hostkeys_foreach: reading file "/root/.ssh/known_hosts" debug3: hostkeys_foreach: reading file "/var/lib/sss/pubconf/known_hosts" debug3: record_hostkey: found key type ED25519 in file /var/lib/sss/pubconf/known_hosts:2 debug3: record_hostkey: found key type RSA in file /var/lib/sss/pubconf/known_hosts:4 debug3: record_hostkey: found key type ECDSA in file /var/lib/sss/pubconf/known_hosts:6
The client only pushes the SSHFP records on enrollment if IPA is serving DNS.
Rob, I’m not sure if we are talking about the same thing. In fact this part works for me too:
debug1: Authenticating to hpclab03:22 as 'root' debug3: hostkeys_foreach: reading file "/var/lib/sss/pubconf/known_hosts" debug3: record_hostkey: found key type ED25519 in file /var/lib/sss/pubconf/known_hosts:2 debug3: record_hostkey: found key type ECDSA in file /var/lib/sss/pubconf/known_hosts:4 debug3: record_hostkey: found key type RSA in file /var/lib/sss/pubconf/known_hosts:6 debug3: load_hostkeys: loaded 3 keys from hpclab03
But it’s not here the problem. The problem is when starting HBA (Hostbased Authentication).
debug1: Next authentication method: hostbased
Here is the problem:
debug3: userauth_hostbased: trying key type ecdsa-sha2-nistp256-cert-v01@openssh.commailto:ecdsa-sha2-nistp256-cert-v01@openssh.com debug3: userauth_hostbased: trying key type ecdsa-sha2-nistp384-cert-v01@openssh.commailto:ecdsa-sha2-nistp384-cert-v01@openssh.com debug3: userauth_hostbased: trying key type ecdsa-sha2-nistp521-cert-v01@openssh.commailto:ecdsa-sha2-nistp521-cert-v01@openssh.com debug3: userauth_hostbased: trying key type ssh-ed25519-cert-v01@openssh.commailto:ssh-ed25519-cert-v01@openssh.com debug3: userauth_hostbased: trying key type ssh-rsa-cert-v01@openssh.commailto:ssh-rsa-cert-v01@openssh.com debug3: userauth_hostbased: trying key type ssh-dss-cert-v01@openssh.commailto:ssh-dss-cert-v01@openssh.com debug3: userauth_hostbased: trying key type ecdsa-sha2-nistp256 debug1: userauth_hostbased: trying hostkey ecdsa-sha2-nistp256 SHA256:Nwwv7gndOGwipEM3I8AGQEUX7OP9LvgFG0V7TXJ0XcI debug2: userauth_hostbased: chost hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br. debug3: send packet: type 50 debug2: we sent a hostbased packet, wait for reply debug3: receive packet: type 51 debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,keyboard-interactive,hostbased debug3: userauth_hostbased: trying key type ecdsa-sha2-nistp256 debug3: userauth_hostbased: trying key type ecdsa-sha2-nistp384 debug3: userauth_hostbased: trying key type ecdsa-sha2-nistp521 debug3: userauth_hostbased: trying key type ssh-ed25519 debug1: userauth_hostbased: trying hostkey ssh-ed25519 SHA256:9O5hkM8gLvGPcoZE9t5zbGxAxHGq7RsCZ5ScjltBZpQ debug2: userauth_hostbased: chost hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br. debug3: send packet: type 50 debug2: we sent a hostbased packet, wait for reply debug3: receive packet: type 51 debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,keyboard-interactive,hostbased debug3: userauth_hostbased: trying key type ssh-ed25519 debug3: userauth_hostbased: trying key type rsa-sha2-512 debug3: userauth_hostbased: trying key type rsa-sha2-256 debug3: userauth_hostbased: trying key type ssh-rsa debug1: userauth_hostbased: trying hostkey ssh-rsa SHA256:+Zl4g2C+AALTHr0K/qkcSDkU6wVQ+CygatAn7x9bRUI debug2: userauth_hostbased: chost hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br. debug3: send packet: type 50 debug2: we sent a hostbased packet, wait for reply debug3: receive packet: type 51 debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,keyboard-interactive,hostbased debug3: userauth_hostbased: trying key type ssh-rsa debug3: userauth_hostbased: trying key type ssh-dss debug1: No more client hostkeys for hostbased authentication.
If I manually create the file: /etc/ssh/ssh_known_hosts with the entries it works, so it’s definitely not looking in /var/lib/sss/pubconf/known_hosts or the proxy isn’t being called during HBA.
If it’s still not clear what I mean I can try to rephrase it.
Thanks again.
rob
If you look at the sshd log there is this: debug1: check_key_in_hostfiles: key for host hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br not found
But if I create the file manually it will work:
debug1: check_key_in_hostfiles: key for hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br found at /etc/ssh/ssh_known_hosts:1
Any ideias?
* Another issue is with the /etc/ssh/shosts.equiv file.
It supports plain hostnames or netgroups, which is a NIS thing. FreeIPA offers any netgroups compatibility? I’m expecting to put something like: @nodes on this file to keep it simple. Any changes on IPA hosts would be reflected automatically.
IPA hostgroups are automatically mirrored as netgroups.
Nice, this worked flawlessly!!!
rob
Thank you very much.
V.
Vinícius Ferrão wrote:
On 15 Oct 2019, at 17:49, Rob Crittenden <rcritten@redhat.com mailto:rcritten@redhat.com> wrote:
Vinícius Ferrão wrote:
Hi Rob
On 15 Oct 2019, at 10:22, Rob Crittenden <rcritten@redhat.com mailto:rcritten@redhat.com mailto:rcritten@redhat.com> wrote:
Vinícius Ferrão via FreeIPA-users wrote:
Hello,
I’m trying to implement SSH Hostbased Authentication between IPA joined machines but I’m with difficulties regarding:
- The /etc/ssh/ssh_known_hosts file.
In a FreeIPA environment the known_hosts are stored on IPA, and I’m aware of the ProxyCommand /usr/bin/sss_ssh_knownhostsproxy; but how can I create this file with the entries from FreeIPA?
Why do you want to? That is the point of the proxy, so dynamic files don't need to be maintained.
Because it appears to be a requirement. Unfortunately SSH does not look at /var/lib/sss/pubconf/known_hosts:
debug1: userauth_hostbased: cuser admin chost hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br. pkalg ecdsa-sha2-nistp256 slen 100 [preauth] debug3: mm_key_allowed entering [preauth] debug3: mm_request_send entering: type 22 [preauth] debug3: mm_key_allowed: waiting for MONITOR_ANS_KEYALLOWED [preauth] debug3: mm_request_receive_expect entering: type 23 [preauth] debug3: mm_request_receive entering [preauth] debug3: mm_request_receive entering debug3: monitor_read: checking request 22 debug3: mm_answer_keyallowed entering debug3: mm_answer_keyallowed: key_from_blob: 0x561842345040 debug2: hostbased_key_allowed: chost hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br. resolvedname hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br ipaddr 172.26.0.1 debug2: stripping trailing dot from chost hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br. debug2: auth_rhosts2: clientuser admin hostname hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br ipaddr 172.26.0.1 debug1: temporarily_use_uid: 1683000000/1683000000 (e=0/0) debug1: restore_uid: 0/0 debug1: fd 8 clearing O_NONBLOCK debug2: hostbased_key_allowed: access allowed by auth_rhosts2 debug1: temporarily_use_uid: 1683000000/1683000000 (e=0/0) debug1: restore_uid: 0/0 debug1: check_key_in_hostfiles: key for host hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br not found debug1: temporarily_use_uid: 1683000000/1683000000 (e=0/0) debug1: restore_uid: 0/0 debug1: check_key_in_hostfiles: key for host hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br not found debug3: mm_answer_keyallowed: key 0x561842345040 is not allowed Failed hostbased for admin from 172.26.0.1 port 55634 ssh2: ECDSA SHA256:wJ0OVmkiVnMjuoiRe5sdBVz5sMTTKIbYRWorTk+CnUQ, client user "admin", client host "hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br”
It does for me:
debug3: hostkeys_foreach: reading file "/root/.ssh/known_hosts" debug3: hostkeys_foreach: reading file "/var/lib/sss/pubconf/known_hosts" debug3: record_hostkey: found key type ED25519 in file /var/lib/sss/pubconf/known_hosts:2 debug3: record_hostkey: found key type RSA in file /var/lib/sss/pubconf/known_hosts:4 debug3: record_hostkey: found key type ECDSA in file /var/lib/sss/pubconf/known_hosts:6
The client only pushes the SSHFP records on enrollment if IPA is serving DNS.
Rob, I’m not sure if we are talking about the same thing. In fact this part works for me too:
You're right, I missed the hostbased-part. I don't know that anyone has tried this before. Perhaps someone from the sssd team would know since they manage the proxy.
rob
On 16 Oct 2019, at 16:01, Rob Crittenden <rcritten@redhat.commailto:rcritten@redhat.com> wrote:
Vinícius Ferrão wrote:
On 15 Oct 2019, at 17:49, Rob Crittenden <rcritten@redhat.commailto:rcritten@redhat.com mailto:rcritten@redhat.com> wrote:
Vinícius Ferrão wrote: Hi Rob
On 15 Oct 2019, at 10:22, Rob Crittenden <rcritten@redhat.commailto:rcritten@redhat.com mailto:rcritten@redhat.com mailto:rcritten@redhat.com> wrote:
Vinícius Ferrão via FreeIPA-users wrote: Hello,
I’m trying to implement SSH Hostbased Authentication between IPA joined machines but I’m with difficulties regarding:
* The /etc/ssh/ssh_known_hosts file.
In a FreeIPA environment the known_hosts are stored on IPA, and I’m aware of the ProxyCommand /usr/bin/sss_ssh_knownhostsproxy; but how can I create this file with the entries from FreeIPA?
Why do you want to? That is the point of the proxy, so dynamic files don't need to be maintained.
Because it appears to be a requirement. Unfortunately SSH does not look at /var/lib/sss/pubconf/known_hosts:
debug1: userauth_hostbased: cuser admin chost hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br. pkalg ecdsa-sha2-nistp256 slen 100 [preauth] debug3: mm_key_allowed entering [preauth] debug3: mm_request_send entering: type 22 [preauth] debug3: mm_key_allowed: waiting for MONITOR_ANS_KEYALLOWED [preauth] debug3: mm_request_receive_expect entering: type 23 [preauth] debug3: mm_request_receive entering [preauth] debug3: mm_request_receive entering debug3: monitor_read: checking request 22 debug3: mm_answer_keyallowed entering debug3: mm_answer_keyallowed: key_from_blob: 0x561842345040 debug2: hostbased_key_allowed: chost hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br. resolvedname hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br ipaddr 172.26.0.1 debug2: stripping trailing dot from chost hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br. debug2: auth_rhosts2: clientuser admin hostname hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br ipaddr 172.26.0.1 debug1: temporarily_use_uid: 1683000000/1683000000 (e=0/0) debug1: restore_uid: 0/0 debug1: fd 8 clearing O_NONBLOCK debug2: hostbased_key_allowed: access allowed by auth_rhosts2 debug1: temporarily_use_uid: 1683000000/1683000000 (e=0/0) debug1: restore_uid: 0/0 debug1: check_key_in_hostfiles: key for host hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br not found debug1: temporarily_use_uid: 1683000000/1683000000 (e=0/0) debug1: restore_uid: 0/0 debug1: check_key_in_hostfiles: key for host hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br not found debug3: mm_answer_keyallowed: key 0x561842345040 is not allowed Failed hostbased for admin from 172.26.0.1 port 55634 ssh2: ECDSA SHA256:wJ0OVmkiVnMjuoiRe5sdBVz5sMTTKIbYRWorTk+CnUQ, client user "admin", client host "hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br”
It does for me:
debug3: hostkeys_foreach: reading file "/root/.ssh/known_hosts" debug3: hostkeys_foreach: reading file "/var/lib/sss/pubconf/known_hosts" debug3: record_hostkey: found key type ED25519 in file /var/lib/sss/pubconf/known_hosts:2 debug3: record_hostkey: found key type RSA in file /var/lib/sss/pubconf/known_hosts:4 debug3: record_hostkey: found key type ECDSA in file /var/lib/sss/pubconf/known_hosts:6
The client only pushes the SSHFP records on enrollment if IPA is serving DNS.
Rob, I’m not sure if we are talking about the same thing. In fact this part works for me too:
You're right, I missed the hostbased-part. I don't know that anyone has tried this before. Perhaps someone from the sssd team would know since they manage the proxy.
rob
Hi again Rob, it’s ok. HBA is not a common thing.
I digged further on this issue and I got almost everything working as expected, except for the known_hosts issue. The netgroup worked through FreeIPA which is what I was looking for. So the only missing piece are the keys.
What is happening is that the server (the destination machine, running sshd) must know the public key of the client (the connecting machine). And by default it looks on /etc/ssh/ssh_known_hosts. I’m almost certain that this is by design for Hostbased Authentication.
This is OK, since I can symlink from /var/lib/sss/pubconf/known_hosts to /etc/ssh/ssh_known_hosts and Hostbased Authentication works! But…
Since the destination machine, haven’t issued any ssh connection to outside, it does not have an /var/lib/sss/pubconf/known_hosts file populated. It does not know about other machines, and when trying to connect with Hostbased it simply fails.
The /var/lib/sss/pubconf/known_hosts file is generated when the ssh client tries to connect to a remote joined IPA host. On /etc/ssh/ssh_config we have this lines:
GlobalKnownHostsFile /var/lib/sss/pubconf/known_hosts PubkeyAuthentication yes ProxyCommand /usr/bin/sss_ssh_knownhostsproxy -p %p %h
But that’s the problem. Only the client runs those commands. Theres nothing similar, or nothing that I know for /etc/ssh/sshd_config, which manages the server configuration.
So that’s the problem basically.
Do you have any ideia who should I contact about this? You said that’s probably from the sssd team but even with this explanation it’s still from sssd? I’m not sure if this will be solved without an RFE or anything like that.
The /usr/bin/sss_ssh_knownhostsproxy executable can be called by sshd, the server daemon during the client connection? If yes perhaps we can find a solution.
Thank you very much Rob.
V.
On Thu, Oct 17, 2019 at 04:32:05AM +0000, Vinícius Ferrão wrote:
On 16 Oct 2019, at 16:01, Rob Crittenden <rcritten@redhat.commailto:rcritten@redhat.com> wrote:
Vinícius Ferrão wrote:
On 15 Oct 2019, at 17:49, Rob Crittenden <rcritten@redhat.commailto:rcritten@redhat.com mailto:rcritten@redhat.com> wrote:
Vinícius Ferrão wrote: Hi Rob
On 15 Oct 2019, at 10:22, Rob Crittenden <rcritten@redhat.commailto:rcritten@redhat.com mailto:rcritten@redhat.com mailto:rcritten@redhat.com> wrote:
Vinícius Ferrão via FreeIPA-users wrote: Hello,
I’m trying to implement SSH Hostbased Authentication between IPA joined machines but I’m with difficulties regarding:
- The /etc/ssh/ssh_known_hosts file.
In a FreeIPA environment the known_hosts are stored on IPA, and I’m aware of the ProxyCommand /usr/bin/sss_ssh_knownhostsproxy; but how can I create this file with the entries from FreeIPA?
Why do you want to? That is the point of the proxy, so dynamic files don't need to be maintained.
Because it appears to be a requirement. Unfortunately SSH does not look at /var/lib/sss/pubconf/known_hosts:
debug1: userauth_hostbased: cuser admin chost hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br. pkalg ecdsa-sha2-nistp256 slen 100 [preauth] debug3: mm_key_allowed entering [preauth] debug3: mm_request_send entering: type 22 [preauth] debug3: mm_key_allowed: waiting for MONITOR_ANS_KEYALLOWED [preauth] debug3: mm_request_receive_expect entering: type 23 [preauth] debug3: mm_request_receive entering [preauth] debug3: mm_request_receive entering debug3: monitor_read: checking request 22 debug3: mm_answer_keyallowed entering debug3: mm_answer_keyallowed: key_from_blob: 0x561842345040 debug2: hostbased_key_allowed: chost hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br. resolvedname hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br ipaddr 172.26.0.1 debug2: stripping trailing dot from chost hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br. debug2: auth_rhosts2: clientuser admin hostname hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br ipaddr 172.26.0.1 debug1: temporarily_use_uid: 1683000000/1683000000 (e=0/0) debug1: restore_uid: 0/0 debug1: fd 8 clearing O_NONBLOCK debug2: hostbased_key_allowed: access allowed by auth_rhosts2 debug1: temporarily_use_uid: 1683000000/1683000000 (e=0/0) debug1: restore_uid: 0/0 debug1: check_key_in_hostfiles: key for host hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br not found debug1: temporarily_use_uid: 1683000000/1683000000 (e=0/0) debug1: restore_uid: 0/0 debug1: check_key_in_hostfiles: key for host hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br not found debug3: mm_answer_keyallowed: key 0x561842345040 is not allowed Failed hostbased for admin from 172.26.0.1 port 55634 ssh2: ECDSA SHA256:wJ0OVmkiVnMjuoiRe5sdBVz5sMTTKIbYRWorTk+CnUQ, client user "admin", client host "hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br”
It does for me:
debug3: hostkeys_foreach: reading file "/root/.ssh/known_hosts" debug3: hostkeys_foreach: reading file "/var/lib/sss/pubconf/known_hosts" debug3: record_hostkey: found key type ED25519 in file /var/lib/sss/pubconf/known_hosts:2 debug3: record_hostkey: found key type RSA in file /var/lib/sss/pubconf/known_hosts:4 debug3: record_hostkey: found key type ECDSA in file /var/lib/sss/pubconf/known_hosts:6
The client only pushes the SSHFP records on enrollment if IPA is serving DNS.
Rob, I’m not sure if we are talking about the same thing. In fact this part works for me too:
You're right, I missed the hostbased-part. I don't know that anyone has tried this before. Perhaps someone from the sssd team would know since they manage the proxy.
rob
Hi again Rob, it’s ok. HBA is not a common thing.
I digged further on this issue and I got almost everything working as expected, except for the known_hosts issue. The netgroup worked through FreeIPA which is what I was looking for. So the only missing piece are the keys.
What is happening is that the server (the destination machine, running sshd) must know the public key of the client (the connecting machine). And by default it looks on /etc/ssh/ssh_known_hosts. I’m almost certain that this is by design for Hostbased Authentication.
This is OK, since I can symlink from /var/lib/sss/pubconf/known_hosts to /etc/ssh/ssh_known_hosts and Hostbased Authentication works! But…
Since the destination machine, haven’t issued any ssh connection to outside, it does not have an /var/lib/sss/pubconf/known_hosts file populated. It does not know about other machines, and when trying to connect with Hostbased it simply fails.
The /var/lib/sss/pubconf/known_hosts file is generated when the ssh client tries to connect to a remote joined IPA host. On /etc/ssh/ssh_config we have this lines:
GlobalKnownHostsFile /var/lib/sss/pubconf/known_hosts PubkeyAuthentication yes ProxyCommand /usr/bin/sss_ssh_knownhostsproxy -p %p %h
But that’s the problem. Only the client runs those commands. Theres nothing similar, or nothing that I know for /etc/ssh/sshd_config, which manages the server configuration.
So that’s the problem basically.
Do you have any ideia who should I contact about this? You said that’s probably from the sssd team but even with this explanation it’s still from sssd? I’m not sure if this will be solved without an RFE or anything like that.
Hi,
yes, this most probably is an RFE for SSSD. Hostbased authentication was not considered when the SSH related features were added to SSSD.
Do I understand correctly that if you link /var/lib/sss/pubconf/known_hosts and /etc/ssh/ssh_known_hosts on the server side and then call
sss_ssh_knownhostsproxy -k client.ipa.domain
to refresh /var/lib/sss/pubconf/known_hosts with the client keys you can connect from the client to the server with hostbased authentication as expected?
The /usr/bin/sss_ssh_knownhostsproxy executable can be called by sshd, the server daemon during the client connection? If yes perhaps we can find a solution.
I'm not aware of an automatic solution. sshd can check authorized keys with the help of AuthorizedKeysCommand but it looks like there is nothing for hostbased authentication.
As a workaround you can create a cron job which calls 'sss_ssh_knownhostsproxy -k client.ipa.domain' for all expected clients on a regular basis to refresh the keys.
HTH
bye, Sumit
Thank you very much Rob.
V.
On 17 Oct 2019, at 03:52, Sumit Bose <sbose@redhat.commailto:sbose@redhat.com> wrote:
On Thu, Oct 17, 2019 at 04:32:05AM +0000, Vinícius Ferrão wrote:
On 16 Oct 2019, at 16:01, Rob Crittenden <rcritten@redhat.commailto:rcritten@redhat.commailto:rcritten@redhat.com> wrote:
Vinícius Ferrão wrote:
On 15 Oct 2019, at 17:49, Rob Crittenden <rcritten@redhat.commailto:rcritten@redhat.commailto:rcritten@redhat.com mailto:rcritten@redhat.com> wrote:
Vinícius Ferrão wrote: Hi Rob
On 15 Oct 2019, at 10:22, Rob Crittenden <rcritten@redhat.commailto:rcritten@redhat.commailto:rcritten@redhat.com mailto:rcritten@redhat.com mailto:rcritten@redhat.com> wrote:
Vinícius Ferrão via FreeIPA-users wrote: Hello,
I’m trying to implement SSH Hostbased Authentication between IPA joined machines but I’m with difficulties regarding:
* The /etc/ssh/ssh_known_hosts file.
In a FreeIPA environment the known_hosts are stored on IPA, and I’m aware of the ProxyCommand /usr/bin/sss_ssh_knownhostsproxy; but how can I create this file with the entries from FreeIPA?
Why do you want to? That is the point of the proxy, so dynamic files don't need to be maintained.
Because it appears to be a requirement. Unfortunately SSH does not look at /var/lib/sss/pubconf/known_hosts:
debug1: userauth_hostbased: cuser admin chost hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br. pkalg ecdsa-sha2-nistp256 slen 100 [preauth] debug3: mm_key_allowed entering [preauth] debug3: mm_request_send entering: type 22 [preauth] debug3: mm_key_allowed: waiting for MONITOR_ANS_KEYALLOWED [preauth] debug3: mm_request_receive_expect entering: type 23 [preauth] debug3: mm_request_receive entering [preauth] debug3: mm_request_receive entering debug3: monitor_read: checking request 22 debug3: mm_answer_keyallowed entering debug3: mm_answer_keyallowed: key_from_blob: 0x561842345040 debug2: hostbased_key_allowed: chost hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br. resolvedname hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br ipaddr 172.26.0.1 debug2: stripping trailing dot from chost hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br. debug2: auth_rhosts2: clientuser admin hostname hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br ipaddr 172.26.0.1 debug1: temporarily_use_uid: 1683000000/1683000000 (e=0/0) debug1: restore_uid: 0/0 debug1: fd 8 clearing O_NONBLOCK debug2: hostbased_key_allowed: access allowed by auth_rhosts2 debug1: temporarily_use_uid: 1683000000/1683000000 (e=0/0) debug1: restore_uid: 0/0 debug1: check_key_in_hostfiles: key for host hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br not found debug1: temporarily_use_uid: 1683000000/1683000000 (e=0/0) debug1: restore_uid: 0/0 debug1: check_key_in_hostfiles: key for host hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br not found debug3: mm_answer_keyallowed: key 0x561842345040 is not allowed Failed hostbased for admin from 172.26.0.1 port 55634 ssh2: ECDSA SHA256:wJ0OVmkiVnMjuoiRe5sdBVz5sMTTKIbYRWorTk+CnUQ, client user "admin", client host "hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br”
It does for me:
debug3: hostkeys_foreach: reading file "/root/.ssh/known_hosts" debug3: hostkeys_foreach: reading file "/var/lib/sss/pubconf/known_hosts" debug3: record_hostkey: found key type ED25519 in file /var/lib/sss/pubconf/known_hosts:2 debug3: record_hostkey: found key type RSA in file /var/lib/sss/pubconf/known_hosts:4 debug3: record_hostkey: found key type ECDSA in file /var/lib/sss/pubconf/known_hosts:6
The client only pushes the SSHFP records on enrollment if IPA is serving DNS.
Rob, I’m not sure if we are talking about the same thing. In fact this part works for me too:
You're right, I missed the hostbased-part. I don't know that anyone has tried this before. Perhaps someone from the sssd team would know since they manage the proxy.
rob
Hi again Rob, it’s ok. HBA is not a common thing.
I digged further on this issue and I got almost everything working as expected, except for the known_hosts issue. The netgroup worked through FreeIPA which is what I was looking for. So the only missing piece are the keys.
What is happening is that the server (the destination machine, running sshd) must know the public key of the client (the connecting machine). And by default it looks on /etc/ssh/ssh_known_hosts. I’m almost certain that this is by design for Hostbased Authentication.
This is OK, since I can symlink from /var/lib/sss/pubconf/known_hosts to /etc/ssh/ssh_known_hosts and Hostbased Authentication works! But…
Since the destination machine, haven’t issued any ssh connection to outside, it does not have an /var/lib/sss/pubconf/known_hosts file populated. It does not know about other machines, and when trying to connect with Hostbased it simply fails.
The /var/lib/sss/pubconf/known_hosts file is generated when the ssh client tries to connect to a remote joined IPA host. On /etc/ssh/ssh_config we have this lines:
GlobalKnownHostsFile /var/lib/sss/pubconf/known_hosts PubkeyAuthentication yes ProxyCommand /usr/bin/sss_ssh_knownhostsproxy -p %p %h
But that’s the problem. Only the client runs those commands. Theres nothing similar, or nothing that I know for /etc/ssh/sshd_config, which manages the server configuration.
So that’s the problem basically.
Do you have any ideia who should I contact about this? You said that’s probably from the sssd team but even with this explanation it’s still from sssd? I’m not sure if this will be solved without an RFE or anything like that.
Hi,
yes, this most probably is an RFE for SSSD. Hostbased authentication was not considered when the SSH related features were added to SSSD.
Do I understand correctly that if you link /var/lib/sss/pubconf/known_hosts and /etc/ssh/ssh_known_hosts on the server side and then call
sss_ssh_knownhostsproxy -k client.ipa.domain
to refresh /var/lib/sss/pubconf/known_hosts with the client keys you can connect from the client to the server with hostbased authentication as expected?
I can confirm: this trick works.
[root@hpclab01 ~]# rm /var/lib/sss/pubconf/known_hosts [root@hpclab01 ~]# !cat cat /var/lib/sss/pubconf/known_hosts cat: /var/lib/sss/pubconf/known_hosts: No such file or directory
[root@hpclab01 ~]# sss_ssh_knownhostsproxy hpclab01 SSH-2.0-OpenSSH_7.4
Protocol mismatch.
[root@hpclab01 ~]# cat /var/lib/sss/pubconf/known_hosts |1|z9KS0phLNWHVVdFsM93CvPft3hM=|EViceVq6CLcj46ZvI+e4KelOb1Y= ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIJEO12B13c3rMzteoSSng11NHCQVJBIr5rZVUG/tbKi6
The /usr/bin/sss_ssh_knownhostsproxy executable can be called by sshd, the server daemon during the client connection? If yes perhaps we can find a solution.
I'm not aware of an automatic solution. sshd can check authorized keys with the help of AuthorizedKeysCommand but it looks like there is nothing for hostbased authentication.
As a workaround you can create a cron job which calls 'sss_ssh_knownhostsproxy -k client.ipa.domain' for all expected clients on a regular basis to refresh the keys.
Yeah, I’m not sure if it will fit my environment. I’m trying to build an HPC system with FreeIPA as identity core. Running a cronjob to fetch the keys on a stateless node I don’t know if this would work as expected and there’s the problem with the hosts. I need to constantly update the node list (dynamically) to fetch keys dynamically. I think it’s too many moving parts to end up breaking.
Anyway, I think I will raise an RFE on SSSD. Where should I open the RFE? Here: https://pagure.io/SSSD/sssd/issues
Thanks guys...
HTH
bye, Sumit
Thank you very much Rob.
V.
On Fri, Oct 18, 2019 at 05:57:40AM +0000, Vinícius Ferrão wrote:
On 17 Oct 2019, at 03:52, Sumit Bose <sbose@redhat.commailto:sbose@redhat.com> wrote:
On Thu, Oct 17, 2019 at 04:32:05AM +0000, Vinícius Ferrão wrote:
On 16 Oct 2019, at 16:01, Rob Crittenden <rcritten@redhat.commailto:rcritten@redhat.commailto:rcritten@redhat.com> wrote:
Vinícius Ferrão wrote:
On 15 Oct 2019, at 17:49, Rob Crittenden <rcritten@redhat.commailto:rcritten@redhat.commailto:rcritten@redhat.com mailto:rcritten@redhat.com> wrote:
Vinícius Ferrão wrote: Hi Rob
On 15 Oct 2019, at 10:22, Rob Crittenden <rcritten@redhat.commailto:rcritten@redhat.commailto:rcritten@redhat.com mailto:rcritten@redhat.com mailto:rcritten@redhat.com> wrote:
Vinícius Ferrão via FreeIPA-users wrote: Hello,
I’m trying to implement SSH Hostbased Authentication between IPA joined machines but I’m with difficulties regarding:
- The /etc/ssh/ssh_known_hosts file.
In a FreeIPA environment the known_hosts are stored on IPA, and I’m aware of the ProxyCommand /usr/bin/sss_ssh_knownhostsproxy; but how can I create this file with the entries from FreeIPA?
Why do you want to? That is the point of the proxy, so dynamic files don't need to be maintained.
Because it appears to be a requirement. Unfortunately SSH does not look at /var/lib/sss/pubconf/known_hosts:
debug1: userauth_hostbased: cuser admin chost hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br. pkalg ecdsa-sha2-nistp256 slen 100 [preauth] debug3: mm_key_allowed entering [preauth] debug3: mm_request_send entering: type 22 [preauth] debug3: mm_key_allowed: waiting for MONITOR_ANS_KEYALLOWED [preauth] debug3: mm_request_receive_expect entering: type 23 [preauth] debug3: mm_request_receive entering [preauth] debug3: mm_request_receive entering debug3: monitor_read: checking request 22 debug3: mm_answer_keyallowed entering debug3: mm_answer_keyallowed: key_from_blob: 0x561842345040 debug2: hostbased_key_allowed: chost hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br. resolvedname hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br ipaddr 172.26.0.1 debug2: stripping trailing dot from chost hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br. debug2: auth_rhosts2: clientuser admin hostname hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br ipaddr 172.26.0.1 debug1: temporarily_use_uid: 1683000000/1683000000 (e=0/0) debug1: restore_uid: 0/0 debug1: fd 8 clearing O_NONBLOCK debug2: hostbased_key_allowed: access allowed by auth_rhosts2 debug1: temporarily_use_uid: 1683000000/1683000000 (e=0/0) debug1: restore_uid: 0/0 debug1: check_key_in_hostfiles: key for host hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br not found debug1: temporarily_use_uid: 1683000000/1683000000 (e=0/0) debug1: restore_uid: 0/0 debug1: check_key_in_hostfiles: key for host hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br not found debug3: mm_answer_keyallowed: key 0x561842345040 is not allowed Failed hostbased for admin from 172.26.0.1 port 55634 ssh2: ECDSA SHA256:wJ0OVmkiVnMjuoiRe5sdBVz5sMTTKIbYRWorTk+CnUQ, client user "admin", client host "hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br”
It does for me:
debug3: hostkeys_foreach: reading file "/root/.ssh/known_hosts" debug3: hostkeys_foreach: reading file "/var/lib/sss/pubconf/known_hosts" debug3: record_hostkey: found key type ED25519 in file /var/lib/sss/pubconf/known_hosts:2 debug3: record_hostkey: found key type RSA in file /var/lib/sss/pubconf/known_hosts:4 debug3: record_hostkey: found key type ECDSA in file /var/lib/sss/pubconf/known_hosts:6
The client only pushes the SSHFP records on enrollment if IPA is serving DNS.
Rob, I’m not sure if we are talking about the same thing. In fact this part works for me too:
You're right, I missed the hostbased-part. I don't know that anyone has tried this before. Perhaps someone from the sssd team would know since they manage the proxy.
rob
Hi again Rob, it’s ok. HBA is not a common thing.
I digged further on this issue and I got almost everything working as expected, except for the known_hosts issue. The netgroup worked through FreeIPA which is what I was looking for. So the only missing piece are the keys.
What is happening is that the server (the destination machine, running sshd) must know the public key of the client (the connecting machine). And by default it looks on /etc/ssh/ssh_known_hosts. I’m almost certain that this is by design for Hostbased Authentication.
This is OK, since I can symlink from /var/lib/sss/pubconf/known_hosts to /etc/ssh/ssh_known_hosts and Hostbased Authentication works! But…
Since the destination machine, haven’t issued any ssh connection to outside, it does not have an /var/lib/sss/pubconf/known_hosts file populated. It does not know about other machines, and when trying to connect with Hostbased it simply fails.
The /var/lib/sss/pubconf/known_hosts file is generated when the ssh client tries to connect to a remote joined IPA host. On /etc/ssh/ssh_config we have this lines:
GlobalKnownHostsFile /var/lib/sss/pubconf/known_hosts PubkeyAuthentication yes ProxyCommand /usr/bin/sss_ssh_knownhostsproxy -p %p %h
But that’s the problem. Only the client runs those commands. Theres nothing similar, or nothing that I know for /etc/ssh/sshd_config, which manages the server configuration.
So that’s the problem basically.
Do you have any ideia who should I contact about this? You said that’s probably from the sssd team but even with this explanation it’s still from sssd? I’m not sure if this will be solved without an RFE or anything like that.
Hi,
yes, this most probably is an RFE for SSSD. Hostbased authentication was not considered when the SSH related features were added to SSSD.
Do I understand correctly that if you link /var/lib/sss/pubconf/known_hosts and /etc/ssh/ssh_known_hosts on the server side and then call
sss_ssh_knownhostsproxy -k client.ipa.domain
to refresh /var/lib/sss/pubconf/known_hosts with the client keys you can connect from the client to the server with hostbased authentication as expected?
I can confirm: this trick works.
[root@hpclab01 ~]# rm /var/lib/sss/pubconf/known_hosts [root@hpclab01 ~]# !cat cat /var/lib/sss/pubconf/known_hosts cat: /var/lib/sss/pubconf/known_hosts: No such file or directory
[root@hpclab01 ~]# sss_ssh_knownhostsproxy hpclab01
Hi,
it might be easier to use the '-k' option. This will print the key to stdout as well but does not try to open a connection.
SSH-2.0-OpenSSH_7.4
Protocol mismatch.
[root@hpclab01 ~]# cat /var/lib/sss/pubconf/known_hosts |1|z9KS0phLNWHVVdFsM93CvPft3hM=|EViceVq6CLcj46ZvI+e4KelOb1Y= ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIJEO12B13c3rMzteoSSng11NHCQVJBIr5rZVUG/tbKi6
The /usr/bin/sss_ssh_knownhostsproxy executable can be called by sshd, the server daemon during the client connection? If yes perhaps we can find a solution.
I'm not aware of an automatic solution. sshd can check authorized keys with the help of AuthorizedKeysCommand but it looks like there is nothing for hostbased authentication.
As a workaround you can create a cron job which calls 'sss_ssh_knownhostsproxy -k client.ipa.domain' for all expected clients on a regular basis to refresh the keys.
Yeah, I’m not sure if it will fit my environment. I’m trying to build an HPC system with FreeIPA as identity core. Running a cronjob to fetch the keys on a stateless node I don’t know if this would work as expected and there’s the problem with the hosts. I need to constantly update the node list (dynamically) to fetch keys dynamically. I think it’s too many moving parts to end up breaking.
Anyway, I think I will raise an RFE on SSSD. Where should I open the RFE? Here: https://pagure.io/SSSD/sssd/issues
Yes, that's the right place.
bye, Sumit
Thanks guys...
HTH
bye, Sumit
Thank you very much Rob.
V.
On 18 Oct 2019, at 03:20, Sumit Bose <sbose@redhat.commailto:sbose@redhat.com> wrote:
On Fri, Oct 18, 2019 at 05:57:40AM +0000, Vinícius Ferrão wrote:
On 17 Oct 2019, at 03:52, Sumit Bose <sbose@redhat.commailto:sbose@redhat.commailto:sbose@redhat.com> wrote:
On Thu, Oct 17, 2019 at 04:32:05AM +0000, Vinícius Ferrão wrote:
On 16 Oct 2019, at 16:01, Rob Crittenden <rcritten@redhat.commailto:rcritten@redhat.commailto:rcritten@redhat.commailto:rcritten@redhat.com> wrote:
Vinícius Ferrão wrote:
On 15 Oct 2019, at 17:49, Rob Crittenden <rcritten@redhat.commailto:rcritten@redhat.commailto:rcritten@redhat.commailto:rcritten@redhat.com mailto:rcritten@redhat.com> wrote:
Vinícius Ferrão wrote: Hi Rob
On 15 Oct 2019, at 10:22, Rob Crittenden <rcritten@redhat.commailto:rcritten@redhat.commailto:rcritten@redhat.commailto:rcritten@redhat.com mailto:rcritten@redhat.com mailto:rcritten@redhat.com> wrote:
Vinícius Ferrão via FreeIPA-users wrote: Hello,
I’m trying to implement SSH Hostbased Authentication between IPA joined machines but I’m with difficulties regarding:
* The /etc/ssh/ssh_known_hosts file.
In a FreeIPA environment the known_hosts are stored on IPA, and I’m aware of the ProxyCommand /usr/bin/sss_ssh_knownhostsproxy; but how can I create this file with the entries from FreeIPA?
Why do you want to? That is the point of the proxy, so dynamic files don't need to be maintained.
Because it appears to be a requirement. Unfortunately SSH does not look at /var/lib/sss/pubconf/known_hosts:
debug1: userauth_hostbased: cuser admin chost hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br. pkalg ecdsa-sha2-nistp256 slen 100 [preauth] debug3: mm_key_allowed entering [preauth] debug3: mm_request_send entering: type 22 [preauth] debug3: mm_key_allowed: waiting for MONITOR_ANS_KEYALLOWED [preauth] debug3: mm_request_receive_expect entering: type 23 [preauth] debug3: mm_request_receive entering [preauth] debug3: mm_request_receive entering debug3: monitor_read: checking request 22 debug3: mm_answer_keyallowed entering debug3: mm_answer_keyallowed: key_from_blob: 0x561842345040 debug2: hostbased_key_allowed: chost hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br. resolvedname hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br ipaddr 172.26.0.1 debug2: stripping trailing dot from chost hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br. debug2: auth_rhosts2: clientuser admin hostname hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br ipaddr 172.26.0.1 debug1: temporarily_use_uid: 1683000000/1683000000 (e=0/0) debug1: restore_uid: 0/0 debug1: fd 8 clearing O_NONBLOCK debug2: hostbased_key_allowed: access allowed by auth_rhosts2 debug1: temporarily_use_uid: 1683000000/1683000000 (e=0/0) debug1: restore_uid: 0/0 debug1: check_key_in_hostfiles: key for host hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br not found debug1: temporarily_use_uid: 1683000000/1683000000 (e=0/0) debug1: restore_uid: 0/0 debug1: check_key_in_hostfiles: key for host hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br not found debug3: mm_answer_keyallowed: key 0x561842345040 is not allowed Failed hostbased for admin from 172.26.0.1 port 55634 ssh2: ECDSA SHA256:wJ0OVmkiVnMjuoiRe5sdBVz5sMTTKIbYRWorTk+CnUQ, client user "admin", client host "hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br http://hpclab01.cluster.iq.ufrj.br”
It does for me:
debug3: hostkeys_foreach: reading file "/root/.ssh/known_hosts" debug3: hostkeys_foreach: reading file "/var/lib/sss/pubconf/known_hosts" debug3: record_hostkey: found key type ED25519 in file /var/lib/sss/pubconf/known_hosts:2 debug3: record_hostkey: found key type RSA in file /var/lib/sss/pubconf/known_hosts:4 debug3: record_hostkey: found key type ECDSA in file /var/lib/sss/pubconf/known_hosts:6
The client only pushes the SSHFP records on enrollment if IPA is serving DNS.
Rob, I’m not sure if we are talking about the same thing. In fact this part works for me too:
You're right, I missed the hostbased-part. I don't know that anyone has tried this before. Perhaps someone from the sssd team would know since they manage the proxy.
rob
Hi again Rob, it’s ok. HBA is not a common thing.
I digged further on this issue and I got almost everything working as expected, except for the known_hosts issue. The netgroup worked through FreeIPA which is what I was looking for. So the only missing piece are the keys.
What is happening is that the server (the destination machine, running sshd) must know the public key of the client (the connecting machine). And by default it looks on /etc/ssh/ssh_known_hosts. I’m almost certain that this is by design for Hostbased Authentication.
This is OK, since I can symlink from /var/lib/sss/pubconf/known_hosts to /etc/ssh/ssh_known_hosts and Hostbased Authentication works! But…
Since the destination machine, haven’t issued any ssh connection to outside, it does not have an /var/lib/sss/pubconf/known_hosts file populated. It does not know about other machines, and when trying to connect with Hostbased it simply fails.
The /var/lib/sss/pubconf/known_hosts file is generated when the ssh client tries to connect to a remote joined IPA host. On /etc/ssh/ssh_config we have this lines:
GlobalKnownHostsFile /var/lib/sss/pubconf/known_hosts PubkeyAuthentication yes ProxyCommand /usr/bin/sss_ssh_knownhostsproxy -p %p %h
But that’s the problem. Only the client runs those commands. Theres nothing similar, or nothing that I know for /etc/ssh/sshd_config, which manages the server configuration.
So that’s the problem basically.
Do you have any ideia who should I contact about this? You said that’s probably from the sssd team but even with this explanation it’s still from sssd? I’m not sure if this will be solved without an RFE or anything like that.
Hi,
yes, this most probably is an RFE for SSSD. Hostbased authentication was not considered when the SSH related features were added to SSSD.
Do I understand correctly that if you link /var/lib/sss/pubconf/known_hosts and /etc/ssh/ssh_known_hosts on the server side and then call
sss_ssh_knownhostsproxy -k client.ipa.domain
to refresh /var/lib/sss/pubconf/known_hosts with the client keys you can connect from the client to the server with hostbased authentication as expected?
I can confirm: this trick works.
[root@hpclab01 ~]# rm /var/lib/sss/pubconf/known_hosts [root@hpclab01 ~]# !cat cat /var/lib/sss/pubconf/known_hosts cat: /var/lib/sss/pubconf/known_hosts: No such file or directory
[root@hpclab01 ~]# sss_ssh_knownhostsproxy hpclab01
Hi,
it might be easier to use the '-k' option. This will print the key to stdout as well but does not try to open a connection.
I think it’s not available on my version… I’m running EL 7.6.
[root@hpclab01 ~]# sss_ssh_knownhostsproxy -k hpclab01 Usage: sss_ssh_knownhostsproxy [-?] [-?|--help] [--usage] [-p|--port INT] [-d|--domain STRING] HOST [PROXY_COMMAND] unknown option[root@hpclab01 ~]# sss_ssh_knownhostsproxy -K hpclab01 Usage: sss_ssh_knownhostsproxy [-?] [-?|--help] [--usage] [-p|--port INT] [-d|--domain STRING] HOST [PROXY_COMMAND] unknown option[root@hpclab01 ~]# rpm -qa | grep -i sssd sssd-common-1.16.2-13.el7_6.8.x86_64 sssd-common-pac-1.16.2-13.el7_6.8.x86_64 sssd-ipa-1.16.2-13.el7_6.8.x86_64 sssd-ldap-1.16.2-13.el7_6.8.x86_64 sssd-1.16.2-13.el7_6.8.x86_64 sssd-krb5-common-1.16.2-13.el7_6.8.x86_64 sssd-ad-1.16.2-13.el7_6.8.x86_64 sssd-krb5-1.16.2-13.el7_6.8.x86_64 sssd-proxy-1.16.2-13.el7_6.8.x86_64 python-sssdconfig-1.16.2-13.el7_6.8.noarch sssd-client-1.16.2-13.el7_6.8.x86_64
SSH-2.0-OpenSSH_7.4
Protocol mismatch.
[root@hpclab01 ~]# cat /var/lib/sss/pubconf/known_hosts |1|z9KS0phLNWHVVdFsM93CvPft3hM=|EViceVq6CLcj46ZvI+e4KelOb1Y= ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIJEO12B13c3rMzteoSSng11NHCQVJBIr5rZVUG/tbKi6
The /usr/bin/sss_ssh_knownhostsproxy executable can be called by sshd, the server daemon during the client connection? If yes perhaps we can find a solution.
I'm not aware of an automatic solution. sshd can check authorized keys with the help of AuthorizedKeysCommand but it looks like there is nothing for hostbased authentication.
As a workaround you can create a cron job which calls 'sss_ssh_knownhostsproxy -k client.ipa.domain' for all expected clients on a regular basis to refresh the keys.
Yeah, I’m not sure if it will fit my environment. I’m trying to build an HPC system with FreeIPA as identity core. Running a cronjob to fetch the keys on a stateless node I don’t know if this would work as expected and there’s the problem with the hosts. I need to constantly update the node list (dynamically) to fetch keys dynamically. I think it’s too many moving parts to end up breaking.
Anyway, I think I will raise an RFE on SSSD. Where should I open the RFE? Here: https://pagure.io/SSSD/sssd/issues
Yes, that's the right place.
Thanks I will do a proper RFE with everything explained and report back here.
bye, Sumit
Thanks guys...
HTH
bye, Sumit
Thank you very much Rob.
V.
Guys, thank you all.
I’ve opened an issue on the SSSD page: https://pagure.io/SSSD/sssd/issue/4106
Feel free to add anything related.
Thanks.
On 18 Oct 2019, at 03:24, Vinícius Ferrão via FreeIPA-users <freeipa-users@lists.fedorahosted.orgmailto:freeipa-users@lists.fedorahosted.org> wrote:
On 18 Oct 2019, at 03:20, Sumit Bose <sbose@redhat.commailto:sbose@redhat.com> wrote:
On Fri, Oct 18, 2019 at 05:57:40AM +0000, Vinícius Ferrão wrote:
On 17 Oct 2019, at 03:52, Sumit Bose <sbose@redhat.commailto:sbose@redhat.commailto:sbose@redhat.com> wrote:
On Thu, Oct 17, 2019 at 04:32:05AM +0000, Vinícius Ferrão wrote:
On 16 Oct 2019, at 16:01, Rob Crittenden <rcritten@redhat.commailto:rcritten@redhat.commailto:rcritten@redhat.commailto:rcritten@redhat.com> wrote:
Vinícius Ferrão wrote:
On 15 Oct 2019, at 17:49, Rob Crittenden <rcritten@redhat.commailto:rcritten@redhat.commailto:rcritten@redhat.commailto:rcritten@redhat.com mailto:rcritten@redhat.com> wrote:
Vinícius Ferrão wrote: Hi Rob
On 15 Oct 2019, at 10:22, Rob Crittenden <rcritten@redhat.commailto:rcritten@redhat.commailto:rcritten@redhat.commailto:rcritten@redhat.com mailto:rcritten@redhat.com mailto:rcritten@redhat.com> wrote:
Vinícius Ferrão via FreeIPA-users wrote: Hello,
I’m trying to implement SSH Hostbased Authentication between IPA joined machines but I’m with difficulties regarding:
* The /etc/ssh/ssh_known_hosts file.
In a FreeIPA environment the known_hosts are stored on IPA, and I’m aware of the ProxyCommand /usr/bin/sss_ssh_knownhostsproxy; but how can I create this file with the entries from FreeIPA?
Why do you want to? That is the point of the proxy, so dynamic files don't need to be maintained.
Because it appears to be a requirement. Unfortunately SSH does not look at /var/lib/sss/pubconf/known_hosts:
debug1: userauth_hostbased: cuser admin chost hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/<http://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/><http://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/> <http://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/> <http://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/>. pkalg ecdsa-sha2-nistp256 slen 100 [preauth] debug3: mm_key_allowed entering [preauth] debug3: mm_request_send entering: type 22 [preauth] debug3: mm_key_allowed: waiting for MONITOR_ANS_KEYALLOWED [preauth] debug3: mm_request_receive_expect entering: type 23 [preauth] debug3: mm_request_receive entering [preauth] debug3: mm_request_receive entering debug3: monitor_read: checking request 22 debug3: mm_answer_keyallowed entering debug3: mm_answer_keyallowed: key_from_blob: 0x561842345040 debug2: hostbased_key_allowed: chost hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/<http://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/><http://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/> <http://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/> <http://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/>. resolvedname hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/<http://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/><http://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/> <http://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/> <http://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/> ipaddr 172.26.0.1 debug2: stripping trailing dot from chost hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/<http://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/><http://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/> <http://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/> <http://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/>. debug2: auth_rhosts2: clientuser admin hostname hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/<http://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/><http://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/> <http://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/> <http://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/> ipaddr 172.26.0.1 debug1: temporarily_use_uid: 1683000000/1683000000 (e=0/0) debug1: restore_uid: 0/0 debug1: fd 8 clearing O_NONBLOCK debug2: hostbased_key_allowed: access allowed by auth_rhosts2 debug1: temporarily_use_uid: 1683000000/1683000000 (e=0/0) debug1: restore_uid: 0/0 debug1: check_key_in_hostfiles: key for host hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/<http://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/><http://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/> <http://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/> <http://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/> not found debug1: temporarily_use_uid: 1683000000/1683000000 (e=0/0) debug1: restore_uid: 0/0 debug1: check_key_in_hostfiles: key for host hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/<http://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/><http://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/> <http://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/> <http://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/> not found debug3: mm_answer_keyallowed: key 0x561842345040 is not allowed Failed hostbased for admin from 172.26.0.1 port 55634 ssh2: ECDSA SHA256:wJ0OVmkiVnMjuoiRe5sdBVz5sMTTKIbYRWorTk+CnUQ, client user "admin", client host "hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/<http://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/><http://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/> <http://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/> <http://hpclab01.cluster.iq.ufrj.brhttp://hpclab01.cluster.iq.ufrj.br/>”
It does for me:
debug3: hostkeys_foreach: reading file "/root/.ssh/known_hosts" debug3: hostkeys_foreach: reading file "/var/lib/sss/pubconf/known_hosts" debug3: record_hostkey: found key type ED25519 in file /var/lib/sss/pubconf/known_hosts:2 debug3: record_hostkey: found key type RSA in file /var/lib/sss/pubconf/known_hosts:4 debug3: record_hostkey: found key type ECDSA in file /var/lib/sss/pubconf/known_hosts:6
The client only pushes the SSHFP records on enrollment if IPA is serving DNS.
Rob, I’m not sure if we are talking about the same thing. In fact this part works for me too:
You're right, I missed the hostbased-part. I don't know that anyone has tried this before. Perhaps someone from the sssd team would know since they manage the proxy.
rob
Hi again Rob, it’s ok. HBA is not a common thing.
I digged further on this issue and I got almost everything working as expected, except for the known_hosts issue. The netgroup worked through FreeIPA which is what I was looking for. So the only missing piece are the keys.
What is happening is that the server (the destination machine, running sshd) must know the public key of the client (the connecting machine). And by default it looks on /etc/ssh/ssh_known_hosts. I’m almost certain that this is by design for Hostbased Authentication.
This is OK, since I can symlink from /var/lib/sss/pubconf/known_hosts to /etc/ssh/ssh_known_hosts and Hostbased Authentication works! But…
Since the destination machine, haven’t issued any ssh connection to outside, it does not have an /var/lib/sss/pubconf/known_hosts file populated. It does not know about other machines, and when trying to connect with Hostbased it simply fails.
The /var/lib/sss/pubconf/known_hosts file is generated when the ssh client tries to connect to a remote joined IPA host. On /etc/ssh/ssh_config we have this lines:
GlobalKnownHostsFile /var/lib/sss/pubconf/known_hosts PubkeyAuthentication yes ProxyCommand /usr/bin/sss_ssh_knownhostsproxy -p %p %h
But that’s the problem. Only the client runs those commands. Theres nothing similar, or nothing that I know for /etc/ssh/sshd_config, which manages the server configuration.
So that’s the problem basically.
Do you have any ideia who should I contact about this? You said that’s probably from the sssd team but even with this explanation it’s still from sssd? I’m not sure if this will be solved without an RFE or anything like that.
Hi,
yes, this most probably is an RFE for SSSD. Hostbased authentication was not considered when the SSH related features were added to SSSD.
Do I understand correctly that if you link /var/lib/sss/pubconf/known_hosts and /etc/ssh/ssh_known_hosts on the server side and then call
sss_ssh_knownhostsproxy -k client.ipa.domain
to refresh /var/lib/sss/pubconf/known_hosts with the client keys you can connect from the client to the server with hostbased authentication as expected?
I can confirm: this trick works.
[root@hpclab01 ~]# rm /var/lib/sss/pubconf/known_hosts [root@hpclab01 ~]# !cat cat /var/lib/sss/pubconf/known_hosts cat: /var/lib/sss/pubconf/known_hosts: No such file or directory
[root@hpclab01 ~]# sss_ssh_knownhostsproxy hpclab01
Hi,
it might be easier to use the '-k' option. This will print the key to stdout as well but does not try to open a connection.
I think it’s not available on my version… I’m running EL 7.6.
[root@hpclab01 ~]# sss_ssh_knownhostsproxy -k hpclab01 Usage: sss_ssh_knownhostsproxy [-?] [-?|--help] [--usage] [-p|--port INT] [-d|--domain STRING] HOST [PROXY_COMMAND] unknown option[root@hpclab01 ~]# sss_ssh_knownhostsproxy -K hpclab01 Usage: sss_ssh_knownhostsproxy [-?] [-?|--help] [--usage] [-p|--port INT] [-d|--domain STRING] HOST [PROXY_COMMAND] unknown option[root@hpclab01 ~]# rpm -qa | grep -i sssd sssd-common-1.16.2-13.el7_6.8.x86_64 sssd-common-pac-1.16.2-13.el7_6.8.x86_64 sssd-ipa-1.16.2-13.el7_6.8.x86_64 sssd-ldap-1.16.2-13.el7_6.8.x86_64 sssd-1.16.2-13.el7_6.8.x86_64 sssd-krb5-common-1.16.2-13.el7_6.8.x86_64 sssd-ad-1.16.2-13.el7_6.8.x86_64 sssd-krb5-1.16.2-13.el7_6.8.x86_64 sssd-proxy-1.16.2-13.el7_6.8.x86_64 python-sssdconfig-1.16.2-13.el7_6.8.noarch sssd-client-1.16.2-13.el7_6.8.x86_64
SSH-2.0-OpenSSH_7.4
Protocol mismatch.
[root@hpclab01 ~]# cat /var/lib/sss/pubconf/known_hosts |1|z9KS0phLNWHVVdFsM93CvPft3hM=|EViceVq6CLcj46ZvI+e4KelOb1Y= ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIJEO12B13c3rMzteoSSng11NHCQVJBIr5rZVUG/tbKi6
The /usr/bin/sss_ssh_knownhostsproxy executable can be called by sshd, the server daemon during the client connection? If yes perhaps we can find a solution.
I'm not aware of an automatic solution. sshd can check authorized keys with the help of AuthorizedKeysCommand but it looks like there is nothing for hostbased authentication.
As a workaround you can create a cron job which calls 'sss_ssh_knownhostsproxy -k client.ipa.domain' for all expected clients on a regular basis to refresh the keys.
Yeah, I’m not sure if it will fit my environment. I’m trying to build an HPC system with FreeIPA as identity core. Running a cronjob to fetch the keys on a stateless node I don’t know if this would work as expected and there’s the problem with the hosts. I need to constantly update the node list (dynamically) to fetch keys dynamically. I think it’s too many moving parts to end up breaking.
Anyway, I think I will raise an RFE on SSSD. Where should I open the RFE? Here: https://pagure.io/SSSD/sssd/issues
Yes, that's the right place.
Thanks I will do a proper RFE with everything explained and report back here.
bye, Sumit
Thanks guys...
HTH
bye, Sumit
Thank you very much Rob.
V.
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