The fixing method of SSH connection failure

□ Restart SSH daemon : service sshd restart

□ Check firewall(iptables) policies to allow SSH service port

○ iptables -L : Check firewall policies
○ iptables -I INPUT -p tcp --dport 22 -j ACCEPT : Insert a policy that allows the SSH service port
○ service iptables stop : Quit the firewall(iptables) service

□ Configure SSH daemon(/etc/ssh/sshd_config)

○ Port 225 : Configure port number
○ PermitRootLogin yes : Configure whether to access the root account
○ Allowusers acnt1 acnt2 acnt3 : Configure accessible accounts