restricting SSH or port 22 from external network

If you have a network like the following :

Eth0 =192.168.0.244 ( or public IP )   gateway 192.168.0.254

Eth1 =10.0.0.1

 

Client pc of network class 10.X should be able to access ssh but not from 192.168.0.X network  then do the following :

 

First check the /etc/services ---- >  look for port 22

 

iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 22  -j REDIRECT --to-port 3128

iptables -t nat -A PREROUTING -i eth0 -p udp --dport 22  -j REDIRECT --to-port 3128

 

all packets that come to eth0 get redirected to our squid application on the same server that works on port 3128 and  you need to configure the squid server to block port 22  

 Similarly you can block for various other ports !!!