Q. I am using Debian stable Linux version and squid proxy server for our small software company. I need to block a port number 1234. How to filter a particular port?
A. You can easily filter any port with squid ACL (Access Control List).
ACL is used for defining an access List. When using “file” the file should contain one item per line By default, regular expressions are CASE-SENSITIVE. To make them case-insensitive, use the -i option.
Procedure to block a port
First open /etc/squid/squid.conf file
# vi /etc/squid/squid.conf
Locate your ACL section and add configuration directive as follows:
acl block_port port 1234
http_access deny block_port
http_access allow all
If you just want to skip a particular IP (192.168.1.5) try as follows:
acl block_port port 1234
acl no_block_port_ip src 192.168.1.5
http_access deny block_port !no_block_port_ip
http_access allow all
Close and save the file.
Restart squid proxy server:
# /etc/init.d/squid restart
