Tag Archives: security

Effective User management under Linux/Unix

In this article, we look into the topic of managing our users on our local Linux/Unix box. As we know it, Linux/Unix is a multiuser environment, therefore, one of the main tasks of a system administrator is to create user accounts and provide a secure environment for users to do their work in.

Adding and removing users is still one of the most important task of a system administrator. Therefore, we as system administrators need a good understanding of how the Linux/Unix accounting system works in order to provide good network services to our users and clients.

Good account management is also the key determinant to system security. Infrequently used accounts are prime targets for crackers. So are accounts with weak passwords.

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Securing your Linux gateway box with IPTABLES

This How-To provides the details for securing a Linux gateway box with the IPTABLES firewall. This guide can be used for Kernels ranging from 2.4-2.6. Special rules for running Squid in transparent mode and providing Network Address Translation (NAT) are also covered in this guide.

The tool IPTABLES talks to the kernel and tells it what packets to filter.

The IPTABLES application operates at a high level by filtering TCP and UDP protocols before the data is passed onto the user applications that can be corrupted.

The IPTABLES tool inserts and deletes rules from the kernel’s packet filtering table.

What this means is that the rules you create in your Linux machine using IPTABLES are lost upon reboot.

The best way to use IPTABLES rules are to store them up in a simple shell script and use your Linux OS to load that script on boot up.

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