Suricata has been added to Debian Backports

Thanks to the hard work of Arturo Borrero Gonzalez, Suricata has just been added to the openlogo-100Debian ‘backports’ repository. This allows users of Debian stable to run up to date versions of Suricata.

The ‘Backports’ repository makes the Suricata and libhtp packages from Debian Testing available to ‘stable’ users. As ‘testing’ is currently in a freeze, it may take a bit of time before 2.0.5 and libhtp 0.5.16 appear.

Anyway, here is how to use it.


First add backports repo to your sources:

# echo "deb wheezy-backports main" > /etc/apt/sources.list.d/backports.list
# apt-get update

As explained here, this will not affect your normal packages.

To prove this, check:

# apt-get install suricata -s
Conf libhtp1 (0.2.6-2 Debian:7.7/stable [amd64])
Conf suricata (1.2.1-2 Debian:7.7/stable [amd64])

Not what we want, as that is still the old version.

To install Suricata from backports, we need to specify the repo:

# apt-get install -t wheezy-backports suricata -s
Conf libhtp1 (0.5.15-1~bpo70+1 Debian Backports:/wheezy-backports [amd64])
Conf suricata (2.0.4-1~bpo70+1 Debian Backports:/wheezy-backports [amd64])

Let’s do it!

# apt-get install -t wheezy-backports suricata
Setting up suricata (2.0.4-1~bpo70+1) ...
[FAIL] suricata disabled, please adjust the configuration to your needs ... failed!
[FAIL] and then set RUN to 'yes' in /etc/default/suricata to enable it. ... failed!

Suricata 2.0.4 is now installed, but it’s not yet running.
To see what features have been compiled in, run:

# suricata --build-info
This is Suricata version 2.0.4 RELEASE

Suricata Configuration:
  AF_PACKET support:                       yes
  PF_RING support:                         no
  NFQueue support:                         yes
  NFLOG support:                           no
  IPFW support:                            no
  DAG enabled:                             no
  Napatech enabled:                        no
  Unix socket enabled:                     yes
  Detection enabled:                       yes

  libnss support:                          yes
  libnspr support:                         yes
  libjansson support:                      yes
  Prelude support:                         yes
  PCRE jit:                                yes
  LUA support:                             yes
  libluajit:                               yes
  libgeoip:                                no
  Non-bundled htp:                         yes
  Old barnyard2 support:                   no
  CUDA enabled:                            no

  Suricatasc install:                      yes

It has Luajit enabled, libjansson for the JSON output, NFQ and AF_PACKET IPS modes, NSS for MD5 checksums and unix sockets. Quite a good feature set.


To get it running, we need a few more steps:

Edit /etc/default/suricata:

1. Change RUN=no to RUN=yes
2. Change LISTENMODE to “af-packet”:

Now lets start it.

# service suricata start
Starting suricata in IDS (af-packet) mode... done.

And confirm that it’s running.

# ps aux|grep suricata
root     20295  1.8  4.1 200212 42544 ?        Ssl  00:50   0:00 /usr/bin/suricata -c /etc/suricata/suricata-debian.yaml --pidfile /var/run/ --af-packet -D

Check if we’re seeing traffic:

# tail /var/log/suricata/stats.log -f|grep capture
capture.kernel_packets    | RxAFPeth01                | 406
capture.kernel_drops      | RxAFPeth01                | 0
capture.kernel_packets    | RxAFPeth11                | 0
capture.kernel_drops      | RxAFPeth11                | 0
capture.kernel_packets    | RxAFPeth01                | 411
capture.kernel_drops      | RxAFPeth01                | 0
capture.kernel_packets    | RxAFPeth11                | 0
capture.kernel_drops      | RxAFPeth11                | 0
capture.kernel_packets    | RxAFPeth01                | 417
capture.kernel_drops      | RxAFPeth01                | 0
capture.kernel_packets    | RxAFPeth11                | 0
capture.kernel_drops      | RxAFPeth11                | 0
capture.kernel_packets    | RxAFPeth01                | 587
capture.kernel_drops      | RxAFPeth01                | 0
capture.kernel_packets    | RxAFPeth11                | 0
capture.kernel_drops      | RxAFPeth11                | 0
capture.kernel_packets    | RxAFPeth01                | 593
capture.kernel_drops      | RxAFPeth01                | 0
capture.kernel_packets    | RxAFPeth11                | 0
capture.kernel_drops      | RxAFPeth11                | 0


As the init script starts Suricata in daemon mode, we need to enable logging to file:

Edit /etc/suricata/suricata-debian.yaml and go to the “logging:” section, there change the “file” portion to look like:

  - file:
      enabled: yes
      filename: /var/log/suricata/suricata.log

Note: in the YAML indentation matters, so make sure it’s exactly right.


Oinkmaster is automatically installed, so lets use that:

First create the rules directory:

mkdir /etc/suricata/rules/

Open /etc/oinkmaster.conf in your editor and add:

url =

Then run:

# oinkmaster -C /etc/oinkmaster.conf -o /etc/suricata/rules
Loading /etc/oinkmaster.conf
Downloading file from done.

Edit /etc/suricata/suricata-debian.yaml and change “default-rule-path” to:

default-rule-path: /etc/suricata/rules

Finally, restart to load the new rules:

# service suricata restart


Now that Suricata is running with rules, lets see if it works:

# wget
--2015-01-08 01:21:30--
Resolving (

This should trigger a specific rule:

# tail /var/log/suricata/fast.log 
01/08/2015-01:21:30.870346  [**] [1:2100498:7] GPL ATTACK_RESPONSE id check returned root [**] [Classification: Potentially Bad Traffic] [Priority: 2] {TCP} ->

Success! 🙂


Thanks to Arturo Borrero Gonzalez for taking on this work for us. Also many thanks for Pierre Chifflier for maintaining the Suricata and libhtp packages in Debian.

Disabling Threading in Tcl8.5 in Debian


I’ve been spending the holidays to upgrade some of my own servers. One of them is the Sguil server I use. Until now it ran Debian Squeeze. On Debian Squeeze you could use tcl8.3, which has threading disabled. For Sguil tcl threading needs to be disabled:

ERROR: This version of tcl was compile with threading enabled. Sguil is NOT compatible with threading.

This is a compile time option in TCL, and the Debian Wheezy packages have it enabled by default. Here are the steps to create your own tcl deb with threading disabled:

# apt-get install dpkg-dev
# apt-get install devscripts

Get the tcl8.5 source package and build deps:

# apt-get source tcl8.5
# apt-get build-dep tcl8.5
# cd tcl8.5-8.5.11/

Next, edit the debian/rules file to disable threading. Remove the line:

                      --enable-threads \

Then, build the package:

# debuild -us -uc

And finally install the package:

# cd ..
# dpkg -i ../tcl8.5_8.5.11-2_amd64.deb

I followed this guide here at Debian Administration. It has some more detail on rebuilding debs.

Vuurmuur 0.8rc1 released

I just released a new Vuurmuur version: 0.8rc1. The first release candidate for the 0.8 series. This release improves IPv6 support a lot. The wizard is now also fully functional. Try “vuurmuur_conf –wizard”.

  • Improved IPv6 support: #115
  • Improved Debian packages, switching to nflog as default for logging.
  • Fix connection viewer not showing accounting on newer systems. #141
  • Amd64 packages for Debian and Ubuntu are now available through the apt server. #83
  • Switch from “state” match to “conntrack” match for connection tracking.
  • Services now support possible protocols. #63
  • Add support for rpfilter match. #137

Get this release from the ftp server:

Additionally, amd64 packages for Debian and Ubuntu are now available. See Installation Debian for instructions.

IPv6 Evasions, Scanners and the importance of staying current

Lots of activity on the IPv6 front lately. There was a talk on a conference on bypassing IDS using IPv6 tricks. Also a new scan tool (Topera) claimed to scan a host while staying below the radar of an IDS was released. To start with the latter, even though Suricata doesn’t have a dedicated port scan detector, the tool’s traffic lights up like a Christmas tree. The trick it pulls is to pack a lot of duplicate DST OPTS extension headers in the IPv6 packets. These options are just fillers, the only options they use are the “pad” option. In Suricata we’ve had an event for duplicate DST OPTS headers since 1.3 and the padding only headers generate an event in 1.4. Both alerts will be very noisy, so calling this a stealth attack rather dubious.

The other thing was a talk on IPv6 evasions, where the author compared Snort and Suricata. Suricata didn’t do very well. Sadly the authors chose not to contact us. On closer inspection it turned out an old Suricata version was used. Which one wasn’t specified, but as they did mention using Security Onion, I’m assuming 1.2. In the 1.3 branch (current stable) we’ve fixed and improved IPv6 in a lot of areas. Nonetheless, while testing the various protocol tricks, we did find some bugs that are now fixed in the git masters for the 1.3 stable branch and the 1.4 development branch.

I think these developments serve as a reminder that staying current with your IDS software’s version is critical. For that reason it’s too bad that distro’s like Security Onion, Debian, Ubuntu all lag significantly. The reasons differ through. For the guys from Security Onion it’s mostly a time problem (so go help them if you can!) for Debian and Ubuntu it’s actually policy. For that reason we’re providing PPAs for Ubuntu and for Debian we’re working on getting Suricata into the “backports” repo. The only mainstream distro that does it right for us is Fedora. They just update to the latest stable as soon as it’s out.

Given the complexity of protocols like IPv6 and the new developments all over the board, I see no viable case for staying on older versions. I know it’s a hassle, but stay current. It’s important.

Removing Trac ticket comment spam in Debian Lenny

The Vuurmuur website runs Trac and overall I’m pretty happy with it. The only thing that Trac doesn’t do well, is dealing with spammers. Spammers target Trac a lot, so that’s a real problem.

To prevent spammers from making it through, I run Scallywhack and a number of custom ModSecurity rules. So far, spams only made it through as new tickets in the ticket tracker, so I installed the TicketDeletePlugin.

Yesterday, I saw the first spam as a comment to an existing and valid ticket. Like tickets themselves, ticket comments can not be removed by Trac by default. Luckily, upstream Trac seems to have fixed this. I’m running Debian’s version of Trac 0.11.1 however, so I decided to patch that. The patches in the Trac ticket #454 didn’t apply cleanly, so I had to patch it manually. To save others the work, it’s available here:

To use it, make a copy of your /usr/share/pyshared/trac directory.
Next, go into the trac directory and run the command:
patch -p1 < /path/to/trac_0.11.1-debian-comment_edit.patch

After this, each comment in the comment system will have a “edit” button and you can remove the spam message content. It’s not possible to remove the entire comment, but this works for me.

Vuurmuur makes it into Debian (Sid)

Thanks to the hard work of Debian’s Daniel Baumann Vuurmuur has been included in Debian unstable/Sid. This hopefully means that Vuurmuur will be getting a lot more users. Eventually it should get into testing and even stable, although the next release “lenny” will come too soon for that. The “lenny” feature freeze was already in place before Vuurmuur got included in Sid. Anyway, for me this is big news!

See here for the packages:

Big thanks to Daniel Bauman!

Compiling Snort_inline with NFQUEUE support on Ubuntu

I needed to setup the right libraries for Snort_inline development on my fresh Ubuntu Feisty installation, so I decided to write down the procedure for those who think compiling Snort_inline from source is hard. 🙂

Make sure you have build-essential package installed. This makes sure you have a compiler and development packages for glibc and other important libraries. I’m installing the libraries from source to get the latest versions because the latest versions are more stable and perform better than the versions included in Feisty. I’m installing them into /usr because some programs like them there best.

Download the library libnfnetlink version 0.0.25 from

$ tar xvfj libnfnetlink-0.0.25.tar.bz2
$ cd libnfnetlink-0.0.25/
$ ./configure --prefix=/usr
$ make
$ sudo make install

Next download libnetfilter_queue version 0.0.13 from

$ tar xvfj libnetfilter_queue-0.0.13.tar.bz2
$ cd libnetfilter_queue-0.0.13
$ ./configure --prefix=/usr
$ make
$ sudo make install

Okay, that sets up the Netfilter libraries.

Next is the installation of libdnet. Do not use the dnet packages from Debian and Ubuntu because this is not the same library as we need for Snort_inline.

Download libdnet 1.11 from

$ tar xzvf libdnet-1.11.tar.gz
$ cd libdnet-1.11
$ ./configure --prefix=/usr
$ make
$ sudo make install

Download snort_inline from

$ tar xvzf snort_inline-
$ cd snort_inline-
$ ./configure --enable-nfnetlink
$ make
$ sudo make install

Test if it works (as root):

# iptables -A OUTPUT -p icmp -j NFQUEUE
# iptables -A INPUT -p icmp -j NFQUEUE
# /usr/local/bin/snort_inline -v -Q -H0

Then ping some host and you should see Snort_inline display the packets. If it doesn’t work, it might be that the kernel modules needed for nfqueue are not yet loaded. Using ‘lsmod’ check if ‘nfnetlink’ and ‘nfnetlink_queue’ are loaded. If not, load them manually.

After this, setup Snort_inline as normal.

Debian should update their Snort package

Last week there was some discussion in the #snort IRC channel about why Debian distributes such an ancient version of Snort, namely version 2.3.3. This release is more than 2 years old and no longer supported by SourceFire. The website says about the old versions:

You should not use these unless you really know what you are doing. Many bugs may have been fixed, including remote vulnerabilities

Even though Debian is able to fix any security bugs themselves, and they don’t need to rely on SourceFire for this, Snort 2.3.3 is still going to be inferior to the recent Why? Well recent Snort versions have many more and improved detection options, such as a better pattern matcher, defragmentation preprocessor, improved stream preprocessor, smtp plugin, etc, etc.

So why is Debian not updating Snort? The answer can be found in the Debian bugtracker. Snort is released under the GPL and up to and including version 2.3.3 included a ruleset. But since then only Snort itself is distributed under the GPL, the (VRT) rules are now under a less free license. Of course the user can get them for free, but with a 30 day delay and only after registering with SourceFire. Big deal, I would say, just remove the rules from the package and put some doc describing how to get rules. But the Debian maintainer doesn’t like this idea:

“Consequently, upgrading to 2.4 would mean providing just an IDS engine, not an IDS “service”.” (source)

I think this reasoning makes no sense, for a number of reasons:

  1. Snort can be useful even without any rules: it can detect anomalies in stream tracking, dns, ftp, http, smtp. It can provide statistics, capture traffic.
  2. Managing the Snort rules through the very static Debian packages system make no sense in the first place. Many of the rules change weekly or even daily. Debian would never update the package for this. Oinkmaster should be used for this, and Debian provides this tool as well.
  3. People can write their own rules.
  4. There still are many free rules available. The Snort community rules are GPL licensed, Bleeding rules are BSD licensed. Together they have thousands of rules.

So Debian, please make your Snort package usable again, and update it to the latest stable version! And while you are at it, provide an inline enabled package as well 😉

Sguil 0.7 CVS installation on Debian Etch

Sguil 0.7 is getting shape quite nicely. One of the most interesting new features is the splitting up of different types of agents and the option to create ‘net groups’. This are groups of agents that Sguil considers part of the same network. You can use this to spread the agents over multiple servers, but still use it from Sguil as if it was one single sensor. For example, this way you can easily create a Snort sensor and a separate full content logging capture server. When you request the full content for a Snort event in Sguil, it will know that it needs to request the packet data from the capture server. This way you can also have multiple Snort agents without the need for capturing the same sancp and full content data over and over again.

David Bianco has written a very nice guide for installing Sguil 0.7 on Redhat Enterprise 4. I used this guide to install the server and sensor on a Debian Etch installation. The main difference is that I used Debian packages where ever possible. These packages could be used:


Important: do not use the tcl8.4 package. It is not compatible with Sguil and will produce the following message:

ERROR: This version of tcl was compile with threading enabled. Sguil is NOT compatible with threading.
SGUILD: Exiting…

You can get Sguil 0.7 CVS by checking out the latest CVS version:

cvs login
cvs co sguil

I will update Modsec2sguil soon!