If you're unable to connect to a server via SSH but ILOM is still accessible, you can use the ILOM console to investigate and resolve the issue. Here's a real-time example of troubleshooting SSH connectivity failure.
Issue:
# ssh test_server
ssh: connect to host test_server port 22: Connection refused
However, ILOM (test_server-ilo) was accessible.
1) Connected to ILOM using SSH:
# ssh test_server-ilo
Password:
->
2) Started the console using the following command:
-> start /HOST/console
Are you sure you want to start /HOST/console (y/n)? y
Serial console started. To stop, type ESC (
test_server login: root
Password:
# pwd
/root
# hostname
test_server
3) Checked if SSH service (sshd) was running:
# ps -ef | grep sshd
If SSH is running, you will see output like:
/usr/sbin/sshd -D
In my case, there was no such process — SSH was not running.
4) Started the SSH service:
# systemctl start sshd.service
✅ This resolved the issue.
🛠 Other Possible Causes
1) SSH is running on a different port
Sometimes, SSH is configured to run on a non-default port (not 22).
# grep ^Port /etc/ssh/sshd_config
Port 2222
In such case, connect using:
# ssh -p 2222 test_server
2) SSH service is disabled or masked
If SSH service is disabled or masked, it won’t start automatically on reboot.
# systemctl status sshd.service
# systemctl unmask sshd.service
# systemctl enable sshd.service
# systemctl start sshd.service
3) Firewall is blocking port 22
If port 22 is blocked by the firewall, SSH will be unreachable from the network.
# firewall-cmd --list-all
# firewall-cmd --add-port=22/tcp --permanent
# firewall-cmd --reload
4) sshd binary missing or corrupted
If the sshd binary or its dependencies are missing or corrupted, SSH service may fail to start.
# which sshd
/usr/sbin/sshd
If not found or broken, reinstall the OpenSSH server package:
# yum reinstall openssh-server
5) ssh_keys group missing in /etc/group
Sometimes the ssh_keys group might be missing in the /etc/group file. To check:
# cat /etc/group | grep ssh
sshd:!:74:
If ssh_keys is missing, add the following line to the /etc/group file:
ssh_keys:x:102:
Then restart the SSH service:
# systemctl start sshd.service
