Error: User modify failed. Cannot modify user on other node: Authentication by SSH key failed!

Check the following on slave/secondary node

1. The error ’User modify failed Cannot modify user on other node: Authentication by ssh key failed’ would occur when the ezeelogin installed node has its public key missing in /root/.ssh/authorized_keys. To add the key, execute the following command

cat /usr/local/etc/ezeelogin/id_clkey.pub >> /root/.ssh/authorized_keys

Check if the key is back in the file.

cat /root/.ssh/authorized_keys

2. Also, make sure that the port sshd is listening on the servers is given as the gateway port in Settings->General->Miscellaneous->Gateway SSH port

3. Also, make sure PubkeyAuthentication is set to ’YES’ in you sshd_config (sshd configuration) file. In Centos/RHEL/Fedora it would be

vi /etc/ssh/sshd_config
#set PubkeyAuthentication to yesPubkeyAuthentication yes
service sshd restart

3. Also, make sure root login is permitted on the gateway server.

You can check this by doing

ssh root@localhost

and it should log you in else edit /etc/ssh/sshd_config and set PermitRootLogin yes

vi /etc/ssh/sshd_config
#Add the following lines to the end of  /etc/ssh/sshd_config to allow root login from localhost only Match Address 127.0.0.1
 PermitRootLogin yes
 service sshd restart

and make sure you are able to authenticate with the the command

ssh root@localhost

Make sure you are able to login after entering the password.

If you have enabled Allow Or Deny SSH Access To A Particular User Or Group in sshd.conf, make sure that the user root is allowed

4. Also, make sure that the webuser(apache,nobody.etc) that the webserver(apache/nginx) runs as is able to read the keys in the dir /usr/local/etc/ezlogin.

Make sure to grant the read privileges to

chmod o r /usr/local/etc/ezlogin/id_clkey
chmod o r /usr/local/etc/ezlogin/id_clkey.pub
or
usermod -G <current_groupname_of_id_clkey_files> <webserver_user>

5. Check the log file /var/log/secure

tail /var/log/secure