Archive for 'Linux Security'

Using Linux auditing to observe program executions and file accesses

Linux systems have a rather nice auditing framework built into the kernel. This framework consists of a kernel component that inspects and filters events and a userland daemon (auditd) that takes the events and archives them to persistent storage. These audit log events can then be searched and summarized with the ausearch and aureport utilities. […]

Tracking Linux UIDs across process creation

When you support mission critical systems it is critically important to know WHAT is running on your systems and WHO is running it. In the past it was sometimes a chore to tell which UID ran a program. This was especially true in the early days when programs fork()’ed and execve()’ed after escalating privileges. The […]

Using the rsyslog MySQL plug-in to send syslog data to a SQL database

I have been experimenting with ways to better manage the logs my servers generate. Depending on who you ask, folks will recommend sending your logs to a remote syslog server that writes the logs to disk, some may recommend sending it to a log analysis tool similar to splunk, and others would recommend feeding it […]

Integrating ssh-agent into your login process

Most of my readers utilize SSH keys to access remote systems. The security benefits are well known, and key-based authentication makes automating remote tasks a whole lot easier. When you use key-based authentication it becomes imperative to protect your private key, since a third party could access your systems if they were able to gain […]

How to figure out if a processes has been chroot()’ed

A number of applications (e.g., custom chroot jails, openssh, vsftp, apache) support the ability to chroot themselves. To find out if a process called chroot() at startup, you can check the /proc/<pid>/root entry for the process. For non-chrooted processes this entry will point to /: $ ps auxwww | grep [s]endmail root 3643 0.0 0.1 […]

Using exec-shield to protect your Linux servers from stack, heap and integer overflows

I’ve been a long time follower of the OpenBSD project, and their amazing work on detecting and protecting the kernel and applications from stack and heap overflows. Several of the concepts that were developed by the OpenBSD team were made available in Linux, and came by way of the exec-shield project. Of the many useful […]

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