CompTIA Server+ (SK0-005)TroubleshootingEasy
A server administrator attempts to log into a Linux server via SSH, but the connection is immediately refused. The administrator confirms that the server is online and reachable via ping. Other services on the server (e.g., HTTP) are functioning correctly. Which of the following is the MOST likely cause?
- AThe administrator's local firewall is blocking SSH connections.
- BThe server's default gateway is misconfigured.
- CThe SSH daemon (sshd) is not running or is misconfigured.
- DThe server's DNS client is misconfigured.
Show answer & explanationAnswer & explanation
Correct answer: C. The SSH daemon (sshd) is not running or is misconfigured.
If the server is online and other services are working, but SSH connections are refused, it strongly suggests that the SSH service itself is not available or is configured incorrectly on the server. The SSH daemon (sshd) must be running and listening on the correct port for connections to be accepted.
Why the other options are wrong
- A. If the local firewall was blocking, the connection would typically time out or be blocked, not immediately refused by the server itself. Also, the question implies server-side troubleshooting.
- B. A misconfigured default gateway would prevent all external network communication, but other services are working.
- D. DNS client misconfiguration would affect hostname resolution, not the acceptance of a direct IP-based SSH connection.
SSH Daemon Status
The SSH daemon (sshd) is the server-side component that listens for and handles incoming SSH connections on a Linux system. If it's not running or misconfigured, SSH connections will fail.
- Responsible for accepting SSH connections.
- Listens on port 22 by default.
- Can be checked using 'systemctl status sshd' or 'service sshd status'.
- Configuration file is typically '/etc/ssh/sshd_config'.
Memory trick: If the door won't open, check if the doorkeeper (daemon) is there and has the right key.