What problem might occur if you connect to a server via SSH, and other users receive information that they cannot connect to the same account via SSH?

One possible reason is exceeding the maximum allowed number of open SSH sessions for a user or at the server level. Other users cannot establish new sessions when the limit is reached.

The cause may be in the SSH server configuration file:

# /etc/ssh/sshd_config
# Example parameters that may limit the number of sessions
MaxSessions 10  # Maximum number of concurrent sessions for all users
MaxStartups 10:30:100 # Maximum number of unfinished connection attempts (10% of 100 to 30% of 100, maximum 100)

Other possible reasons:

• IP blocking: If the SSH server uses a firewall or fail2ban, IP addresses of other users may be temporarily blocked due to failed login attempts.
• Server resource issues: Lack of RAM or CPU resources can prevent new SSH sessions from being established.
• Incorrect file permissions: If .ssh/authorized_keys or the user's home directory have incorrect permissions, other users may not be able to log in.
• Authentication issues: Other users may have incorrect SSH keys or passwords (if password authentication is enabled).

To diagnose the problem, you should:

1. Check SSH server logs (/var/log/auth.log or secure).
2. Check sshd_config settings.
3. Check firewall and fail2ban status.
4. Check server resource usage (top, htop).
5. Check permissions of files in the user's home directory.