Under SYSTEM > Firewall > Open TCP ports: one of the ports I have is 4711. However, when I go to check if the port is open using a port checker tool such as this it's showing port 4711 is closed. I tried to add port to IP Tables iptables -A INPUT -p udp -m udp --dport 4711 -j ACCEPT without any luck. Port 4711 is still showing closed. UFW firewall is disabled on my server. I called my ISP they do not block 4711. Any suggestions how to open port 4711?
I'm not sure if the check tool you used is able to identify an open port in the firewall, I guess it will be able to detect a running service only but not an open port without a service. The first thing you might check is if there is really a service listening on that port UDP on your server: netstat -ntap | grep 4711 To check if that port is open in the firewall, use the iptables command: iptables -L
I want to use port 4711 for dovecot sync to sync mail between (server1 & server 2) When I do netstat -ntap | grep 4711 nothing returns server1 > iptables -L Chain INPUT (policy ACCEPT) target prot opt source destination ACCEPT tcp -- anywhere anywhere tcp dpt:4711 fail2ban-postfix-sasl tcp -- anywhere anywhere multiport dports smtp fail2ban-dovecot-pop3imap tcp -- anywhere anywhere multiport dports pop3,pop3s,imap2,imaps fail2ban-pureftpd tcp -- anywhere anywhere multiport dports ftp fail2ban-ssh tcp -- anywhere anywhere multiport dports ssh ACCEPT udp -- anywhere anywhere udp dpt:4711 Chain FORWARD (policy ACCEPT) target prot opt source destination Chain OUTPUT (policy ACCEPT) target prot opt source destination Chain fail2ban-dovecot-pop3imap (1 references) target prot opt source destination RETURN all -- anywhere anywhere Chain fail2ban-postfix-sasl (1 references) target prot opt source destination RETURN all -- anywhere anywhere Chain fail2ban-pureftpd (1 references) target prot opt source destination RETURN all -- anywhere anywhere Chain fail2ban-ssh (1 references) target prot opt source destination REJECT all -- 58.242.83.7 anywhere reject-with icmp-port-unreachable RETURN all -- anywhere anywhere server 2 > iptables -L Chain INPUT (policy ACCEPT) target prot opt source destination ACCEPT tcp -- anywhere anywhere tcp dpt:4711 ACCEPT tcp -- anywhere anywhere tcp dpt:4711 ACCEPT tcp -- anywhere anywhere tcp dpt:4711 ACCEPT udp -- anywhere anywhere udp dpt:4711 ACCEPT udp -- anywhere anywhere udp dpt:4711 Chain FORWARD (policy ACCEPT) target prot opt source destination Chain OUTPUT (policy ACCEPT) target prot opt source destination If I understand correctly, does this mean port 4711 is open but no service listening on that port?
