Adding mail ports to Linux firewall with iptables

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So a customer had flushed his iptables rules, and sadly wasn’t able to use SMTP and POP. So I put together this basic tutorial explaining how to do it!


The following ports are used for mail commonly:

SMTP 	587
POP 	110
POPS 	995
IMAP 	143
IMAP3 	993

To add these ports to the firewall rules;

# Allows SMTP access

iptables -A INPUT -p tcp --dport 25 -j ACCEPT 

# Allows pop and pops connections 

iptables -A INPUT -p tcp --dport 110 -j ACCEPT
iptables -A INPUT -p tcp --dport 995 -j ACCEPT

# Allows imap and imaps connections 

iptables -A INPUT -p tcp --dport 143 -j ACCEPT
iptables -A INPUT -p tcp --dport 993 -j ACCEPT