Thread: Blocking ports in linux

How do i block ports in linux as i do not want to give access to everyone...
How do i block a single port ?
How do i block a single port for specfic IP?

thanks in advnace

The easiest way to block particular TCP port in Linux is use iptables rule as follows:

Code:

iptables -A INPUT -p tcp --destination-port PORT-NUBMER -j DROP

For example block port 22 for everyone:

Code:

iptables -A INPUT -p tcp --destination-port 22 -j DROP

Now let us say you want block port 22 for everyone except for IP 202.65.11.10

Code:

iptables -A INPUT -p tcp --destination-port 22 -s \! 202.65.11.10 -j DROP

To block UDP ports use --tcp udp option:

Code:

iptables -A INPUT -p udp --destination-port PORT-NUBMER -j DROP