Here are 8 tips to improve your Linux security. On second thought these tip will help to improve your security as a whole.
1. Install a Firewall
Linux has great support for firewall, Netfilter specifically. Firewalls filter packets, only allowing packets that match you predetermined rule set to be passed along. The hooks for Netfilter can be compiled into the Linux kernel. Iptables commands can be based on IP address, ports, protocols, or combinations of these. The L7 project allows for Layer 7 filtering (note L7 is not 100% accurate on all applications). After creating your firewall, test, test, test, and test more. Make sure you plug any and all hole you might find. Once you firewall is in place, review the firewall on a regular basis, keep the firewall software up-to-date. Change you rules to match your needs at the same time.
2. Disable unneeded services/daemons
Disable or remove any daemons that you do not use, this will not only lighten the resources needed to run your servers or workstations, it will improve your security. If you do not need Samba then why run the risk of someone being able to hack into your system using Samba. Services like Samba, NFS, and telnet are open doors for crackers to gain access through. Close the doors you do not plan on using. Most services can be shutoff from /etc/initd.conf, /etc/xinitd.conf, or /etc/rc.d/ directory.
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