The simplest iptables settings that I commonly use

# Firewall configuration written by system-config-firewall

# Manual customization of this file is not recommended.

*filter

:INPUT ACCEPT [0:0]

:FORWARD ACCEPT [0:0]

:OUTPUT ACCEPT [0:0]

-A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT

-A INPUT -p icmp -j ACCEPT

-A INPUT -i lo -j ACCEPT

#-A INPUT -m state --state NEW -m tcp -p tcp --dport 22 -j ACCEPT

 

-A INPUT -m state --state NEW -p tcp -s xxx.xxx.xxx.xx  --dport 22 -j ACCEPT

-A INPUT -m state --state NEW -p tcp -s xxx.xxx.xxx.xx --dport 443 -j ACCEPT

 

-A INPUT -m state --state NEW -m tcp -p tcp --dport xxxx  -j ACCEPT

#-A INPUT -m state --state NEW -m tcp -p tcp --dport 80 -j ACCEPT

-A INPUT -j REJECT --reject-with icmp-host-prohibited

-A FORWARD -j REJECT --reject-with icmp-host-prohibited

COMMIT