Latest revision as of 07:31, 13 September 2012

Description

SSH public key management and OpenSSH integration.

Setup

Make sure you have SSSD 1.9.0beta7 or later installed (Koji build).
Install FreeIPA server with DNS on one machine, server.ipa.example.com, and FreeIPA client on another machine, client.ipa.example.com (see Basic installation tests).

How to test

Verify installation

First authenticate as admin:

user@server$ kinit admin

Verify that the host entry of server.ipa.example.com has the correct SSH public keys set:

user@server$ ipa host-show server.ipa.example.com --all
Host name: server.ipa.example.com
Principal name: host/server.ipa.example.com@IPA.EXAMPLE.COM
SSH public key fingerprint: 5A:CE:70:8F:A3:AF:57:C1:D1:C0:C6:28:FC:D4:42:07 (ssh-dss), 76:2B:1F:98:1C:02:EE:29:43:C1:18:FD:75:57:36:8F (ssh-rsa)
Password: False
Keytab: True
Managed by: server.ipa.example.com

user@server$ ssh-keygen -l -f /etc/ssh/ssh_host_dsa_key.pub
1024 5a:ce:70:8f:a3:af:57:c1:d1:c0:c6:28:fc:d4:42:07 (DSA)

user@server$ ssh-keygen -l -f /etc/ssh/ssh_host_rsa_key.pub
2048 76:2b:1f:98:1c:02:ee:29:43:c1:18:fd:75:57:36:8f (RSA)

The same procedure can be used to verify host public keys of client.ipa.example.com.

Verify that DNS SSHFP records were updated correctly:

user@server$ dig +short server.ipa.example.com SSHFP
2 1 D017B7B96C1CF0DC9A9CC317AED198EBE61C8369
1 1 EEA71C381935401361301366B2E4E2627CB470CD

user@server$ ssh-keygen -r server.ipa.example.com -f /etc/ssh/ssh_host_dsa_key.pub
server.ipa.example.com IN SSHFP 2 1 d017b7b96c1cf0dc9a9cc317aed198ebe61c8369

user@server$ ssh-keygen -r server.ipa.example.com -f /etc/ssh/ssh_host_rsa_key.pub
server.ipa.example.com IN SSHFP 1 1 eea71c381935401361301366b2e4e2627cb470cd

Again, the same procedure can be used to verify DNS SSHFP records of client.ipa.example.com.

Public key management

Generate a SSH keypair and create new FreeIPA user with the public key set:

user@server$ ssh-keygen -t rsa

user@server$ ipa user-add sshuser --first=SSH --last=User --sshpubkey=‘cat .ssh/id_rsa.pub‘

Verify that the user entry has the correct SSH public key set:

user@server$ ipa user-show sshuser
User login: sshuser
First name: SSH
Last name: User
Home directory: /home/sshuser
Login shell: /bin/sh
UID: 12345678
GID: 12345678
Account disabled: False
SSH public key fingerprint: 38:FA:5A:79:DF:21:D6:C6:EC:F0:5C:98:8A:4F:AF:04 user@server.ipa.example.com (ssh-rsa)
Password: False
Member of groups: ipausers
Kerberos keys available: False

user@server$ ssh-keygen -l -f .ssh/id_rsa.pub
2048 38:fa:5a:79:df:21:d6:c6:ec:f0:5c:98:8a:4f:af:04 user@server.ipa.example.com (RSA)

Generate another SSH keypair on client.ipa.example.com:

user@client$ ssh-keygen -t rsa

user@client$ cat .ssh/id_rsa.pub
ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQCcuiedn5g9vECbjDaboheZ6yZ/ra6fM0YlAzS6bEh6HsH64AaQRih29L0sWygCIjhTPxO4gIaAzC4mrZjFnMbV3GPWhEisU33vJ8fqSmQZaAWAyV+aNIWMZRHIMgvBf+sTPYiMCzH7hkzDjljKHOTnMoDoOJ8cCNalC+KxDfSDDEulo/hmEYNTDQHrQJMtu+X3h7Z/EGbmeYlTFzneNZ/E6BkfCU/as3ViRy+DwKAZ2NPpozh/AEkVEVr76zoqMYuuqk5cyhXDJFeve/qJjBK/JqaGanPk8bxqpYYk6MbNXfP70HBP+8FAZaj53tJBYCB2aIc8+ZlF3z2ZCrh4hUKt user@client.ipa.example.com

Add the public key to sshuser:

user@server$ ipa user-mod sshuser --addattr ipasshpubkey='ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQCcuiedn5g9vECbjDaboheZ6yZ/ra6fM0YlAzS6bEh6HsH64AaQRih29L0sWygCIjhTPxO4gIaAzC4mrZjFnMbV3GPWhEisU33vJ8fqSmQZaAWAyV+aNIWMZRHIMgvBf+sTPYiMCzH7hkzDjljKHOTnMoDoOJ8cCNalC+KxDfSDDEulo/hmEYNTDQHrQJMtu+X3h7Z/EGbmeYlTFzneNZ/E6BkfCU/as3ViRy+DwKAZ2NPpozh/AEkVEVr76zoqMYuuqk5cyhXDJFeve/qJjBK/JqaGanPk8bxqpYYk6MbNXfP70HBP+8FAZaj53tJBYCB2aIc8+ZlF3z2ZCrh4hUKt user@client.ipa.example.com'

You can experiment further with ipa user-add, ipa user-mod, ipa host-add, ipa host-mod commands, all of them allow setting SSH public keys (in OpenSSH authorized_keys format, see man sshd) using the --sshpubkey option. Note that --sshpubkey overwrites the public keys of user or host with the new value(s), if you want to add or delete public keys, you have to use --addattr ipasshpubkey=... or --delattr ipasshpubkey=... instead.

OpenSSH integration

Now that public keys for both hosts and user are set, you can try using ssh to log in remotely from server.ipa.example.com to client.ipa.example.com and vice-versa:

user@server$ ssh sshuser@client

user@client$ ssh sshuser@server

Both these commands should work without any warnings or errors and should NOT prompt for verification of host identity or password.

Expected Results

All the test steps should end with the specified results.

@@ Line 56: / Line 56: @@
   user@server$ ssh-keygen -t rsa
-  user@server$ ipa user-add user --uid=$UID --first=User --last=Test --sshpubkey=‘cat .ssh/id_rsa.pub‘
+  user@server$ ipa user-add sshuser --first=SSH --last=User --sshpubkey=‘cat .ssh/id_rsa.pub‘
 Verify that the user entry has the correct SSH public key set:
-  user@server$ ipa user-show user
+  user@server$ ipa user-show sshuser
-  User login: user
+  User login: sshuser
-  First name: User
+  First name: SSH
-  Last name: Test
+  Last name: User
-  Home directory: /home/user
+  Home directory: /home/sshuser
   Login shell: /bin/sh
-  UID: 1000
+  UID: 12345678
-  GID: 1000
+  GID: 12345678
   Account disabled: False
   SSH public key fingerprint: <span style="color: blue">38:FA:5A:79:DF:21:D6:C6:EC:F0:5C:98:8A:4F:AF:04</span> user@server.ipa.example.com (ssh-rsa)
@@ Line 77: / Line 77: @@
 <span style="color: blue">38:fa:5a:79:df:21:d6:c6:ec:f0:5c:98:8a:4f:af:04</span> user@server.ipa.example.com (RSA)
-You can experiment further with <code>ipa user-add</code>, <code>ipa user-mod</code>, <code>ipa host-add</code>, <code>ipa host-mod</code> commands, all of them allow setting SSH public keys (in OpenSSH authorized_keys format, see <code>man sshd</code>) using the <code>--sshpubkey</code> option. Note that you can't use <code>--sshpubkey</code> to add or delete public keys of a user or host, you have to use <code>--addattr ipasshpubkey=...</code> or <code>--delattr ipasshpubkey=...</code> instead.
+Generate another SSH keypair on <code>client.ipa.example.com</code>:
+ user@client$ ssh-keygen -t rsa
+ user@client$ cat .ssh/id_rsa.pub
+ <span style="color: purple">ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQCcuiedn5g9vECbjDaboheZ6yZ/ra6fM0YlAzS6bEh6HsH64AaQRih29L0sWygCIjhTPxO4gIaAzC4mrZjFnMbV3GPWhEisU33vJ8fqSmQZaAWAyV+aNIWMZRHIMgvBf+sTPYiMCzH7hkzDjljKHOTnMoDoOJ8cCNalC+KxDfSDDEulo/hmEYNTDQHrQJMtu+X3h7Z/EGbmeYlTFzneNZ/E6BkfCU/as3ViRy+DwKAZ2NPpozh/AEkVEVr76zoqMYuuqk5cyhXDJFeve/qJjBK/JqaGanPk8bxqpYYk6MbNXfP70HBP+8FAZaj53tJBYCB2aIc8+ZlF3z2ZCrh4hUKt user@client.ipa.example.com</span>
+Add the public key to <code>sshuser</code>:
+ user@server$ ipa user-mod sshuser --addattr ipasshpubkey='<span style="color: purple">ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQCcuiedn5g9vECbjDaboheZ6yZ/ra6fM0YlAzS6bEh6HsH64AaQRih29L0sWygCIjhTPxO4gIaAzC4mrZjFnMbV3GPWhEisU33vJ8fqSmQZaAWAyV+aNIWMZRHIMgvBf+sTPYiMCzH7hkzDjljKHOTnMoDoOJ8cCNalC+KxDfSDDEulo/hmEYNTDQHrQJMtu+X3h7Z/EGbmeYlTFzneNZ/E6BkfCU/as3ViRy+DwKAZ2NPpozh/AEkVEVr76zoqMYuuqk5cyhXDJFeve/qJjBK/JqaGanPk8bxqpYYk6MbNXfP70HBP+8FAZaj53tJBYCB2aIc8+ZlF3z2ZCrh4hUKt user@client.ipa.example.com</span>'
+You can experiment further with <code>ipa user-add</code>, <code>ipa user-mod</code>, <code>ipa host-add</code>, <code>ipa host-mod</code> commands, all of them allow setting SSH public keys (in OpenSSH authorized_keys format, see <code>man sshd</code>) using the <code>--sshpubkey</code> option. Note that <code>--sshpubkey</code> overwrites the public keys of user or host with the new value(s), if you want to add or delete public keys, you have to use <code>--addattr ipasshpubkey=...</code> or <code>--delattr ipasshpubkey=...</code> instead.
 === OpenSSH integration ===
@@ Line 83: / Line 94: @@
 Now that public keys for both hosts and user are set, you can try using ssh to log in remotely from <code>server.ipa.example.com</code> to <code>client.ipa.example.com</code> and vice-versa:
-  user@server$ ssh user@client
+  user@server$ ssh sshuser@client
-  user@client$ ssh user@server
+  user@client$ ssh sshuser@server
 Both these commands should work without any warnings or errors and should '''NOT''' prompt for verification of host identity or password.

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