Linux Iptables Block Outgoing Access To Selected or Specific IP Address / Port

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You would like to block outgoing access to particular remote host/ip or port for all or selected service/port. In this quick tutorial I will explain how to use iptables to block outgoing access.

Block Access To Outgoing IP Address

The following rule will block ip address 202.54.1.22 from making any outgoing connection:

iptables -A OUTPUT -d 202.54.1.22 -j DROP

The above will block chat server ip address or site having dangerous contains such as viruses or malware.

Block Access To Outgoing IP TCP / UDP Port Number

To block specific port number such tcp port # 5050, enter:

iptables -A OUTPUT -p tcp --dport 5050 -j DROP

To block tcp port # 5050 for an IP address 192.168.1.2 only, enter:

iptables -A OUTPUT -p tcp -d 192.168.1.2 --dport 5050 -j DROP

Finally, you need to
save your firewall rules. Under CentOS / RHEL / Fedora Linux, enter:

# /sbin/service iptables save

OR

# /etc/init.d/iptables save

For more information see
Linux iptables(8) man page or our Linux firewall tutorials from the following resources: