Nitro-Security on Inliniac

DC meeting

Tue, 21 Jul 2009 16:33:27 +0000

So I just got back from Washington D.C. where we had our first public meeting for the OISF. I think it went very well as there were more people than expected. The attendees came from all parts from the industry & government. Overall reception was very positive and we’ve gotten many offers for help in development & testing.

Around the public meetings we had private meetings with a number of companies and I’m very happy that three of them commited to the project already:

Snort_inline load balancing

Thu, 18 Sep 2008 11:32:40 +0000

Dave Remien of NitroSecurity created a patch that “implements a relatively simple form of (IPV4) load balancing” between multiple Snort_inline processes using Nfqueue. Here is what it does:

1. Load balancing. The bottom half of the source and dest addresses are added together, and mod’d with the number of “load-balancing” snorts you desire to run. This means that traffic stays with a particular snort, so that state is maintained.

2. Because you can run many snorts (presumably on many CPUs), you can now take advantage of that super-hooty 16way box and those 10 gig NICs you just got your hands on…

Tunnel unwrapping for Snort_inline 2.8.0.1

Fri, 11 Jan 2008 16:24:37 +0000

Not many people have native IPv6 connectivity and use some form of tunneling. For this reason Nitro Security asked me to develop a Snort preprocessor to unwrap various tunnels. This resulted in the preprocessor ‘ip6tunnel’, which I uploaded to Snort_inline’s SVN yesterday. The preprocessor is capable of unwrapping IPv6-in-IPv4, IPv6-in-IPv6, IPv4-in-IPv6, IPv4-in-IPv4 and finally IPv6-over-UDP. The latter is used by Freenet6.

I chose to develop it as a preprocessor because this allows Snort to inspect both the original packet and the tunnel packet(s). The preprocessor supports recursive unwrapping. The recursion depth is limited to 3 by default, but can be configured differently. Get the preprocessor from Snort_inline’s SVN by checking out the latest trunk:

Snort_inline updated to 2.8.0.1 in SVN

Wed, 09 Jan 2008 15:41:19 +0000

I’ve just committed an update to Snort_inline’s SVN. It brings it to the Snort 2.8.0.1 level. It supports both IPv4 and IPv6 on IPQ and NFQ. I have not been able to test IPFW on IPv6, so I don’t think that will work currently.

This update removes the libdnet dependency and replaces it with libnet 1.1. To be able to send ICMPv6 unreachable packets you will need the libnet 1.1 patch I wrote a while ago. You can find that here. Get the latest Snort_inline by checking out SVN:

Working on Snort_inline 2.8.0.1

Sat, 22 Dec 2007 12:49:20 +0000

The last week I’ve been working on bringing Snort_inline to the Snort 2.8.0.1 level, including it’s IPv6 support. I’m almost ready to commit it to SVN, there are just some issues I need to fix in the inline specific code. The code will get rid of libdnet and use libnet 1.1 for sending reset/reject packets for both IPv4 and IPv6. After committing I will start working on getting the IPv6 features I wrote for NitroSecurity into this tree. This includes more matches, tunnel decoding (including for example the freenet6 tunnel, etc). So stay tuned!

Libnet 1.1 IPv6 fixes and additions

Tue, 16 Oct 2007 21:35:11 +0000

Libnet is a cool packet crafting tool, used by Snort to send TCP reset packets and ICMP unreachable packets as part of active responses. Libnet 1.1 supports IPv6 which is what I needed for my work. After some reading and testing there were a few problems. First, while possible to send TCP reset packets, the packets didn’t have a correct checksum and debugging this with valgrind showed lots of memory errors. Second, ICMPv6 was only partly implemented. The libnet_build_* functions for it are missing. This is, by the way, quite a common picture. Many libraries and projects have some support for IPv6, but generally incomplete and less well tested.

Differences between Snort and Snort_inline

Mon, 14 May 2007 17:05:41 +0000

Every few weeks the same question comes up: what is the difference between Snort in inline mode and Snort_inline. This makes sense, because the Snort_inline documentation and website fail to explain it. In this post I will try to highlight the main differences. In general I can say that we try to develop Snort_inline as a patchset on top of Snort. Snort_inline is focused at improving the inline part of Snort. Originally of course, Snort’s inline capabilities were developed in the Snort_inline project. With Snort 2.3.0RC1 they were merged into mainline Snort.