Using stunnel for mutual authentication

Sometimes services do not support SSL/TLS, or if they do, they do not support using mutual authentication (i.e. requesting that the client also provides a certificate which is trusted by the service). If that is a requirement in your architecture, you can use stunnel to provide this additional …

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Perimeter security testing

I've been asked a few times how I would do perimeter security testing. Personally, I'm not an offensive security guy, more a defensive one, meaning I'm more about security-related defensive methods rather than PEN testing of any kind. But still, even in a defensive position, having a "view" on how …

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Hardening the Linux kernel updates

Thanks to a comment by Andy, the guide now has information about additional settings: stackprotector, read-only data, restrict access to /dev/mem, disable /proc/kcore and restrict kernel syslog (dmesg). One suggestion he made didn't make it to the guide (about CONFIG_DEBUG_STACKOVERFLOW) since I can't find any resources about the …

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Hardening OpenSSH

A while ago I wrote about a Gentoo Security Benchmark which would talk about hardening a Gentoo Linux installation. Within that document, I was documenting how to harden specific services as well. However, I recently changed my mind and wanted to move the hardening stuff for the services in separate …

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Why both chroot and SELinux?

In my previous post, a very valid question was raised by Alexander E. Patrakov: why still use chroot if you have SELinux?

Both chroot (especially with the additional restrictions that grSecurity enables on chroots that make it more difficult to break out of a chroot) and SELinux try to isolate …

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Mitigating risks, part 3 - hardening

While I'm writing this post, my neighbor is shouting. He's shouting so hard, that I was almost writing with CAPS on to make sure you could read me. But don't worry, he's not fighting - it is how he expresses his (positive) feelings about his religion.

Security is, for some, also …

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