iptables Archives

How to trace source, destination IP addresses and ports using tcpdump

By Fuad NAHDI April 19, 2010

Today I just has been alerted that there are too many 'Relay access denied' in my mail server. It is not normal. It must be any clients/workstations infected by viruses and try to relay to my mail server.

Linux

How to redirect or forward port using iptables on Linux

By Fuad NAHDI March 2, 2010

You have a Local Area Network (LAN) that using Linux as a router. In the Linux box there are two network interface card (NIC) attached to it, one has public IP that connect to Internet Service Provider (ISP) and the other one has private IP address that connect to the LAN.

Linux

How to block unmatched IP and MAC Address using iptables

By Fuad NAHDI January 28, 2010

In a Local Area Network (LAN), sometime you need to divide policy access based-on IP Address. For example, only specific IP addresses can access the web, email, FTP, facebook and so forth. Others will be dropped.