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 http://ftp.netfilter.org/pub/libnfnetlink/

$ 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 http://ftp.netfilter.org/pub/libnetfilter_queue/

$ 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 http://libdnet.sourceforge.net/

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

Download snort_inline 2.6.1.5 from http://snort-inline.sourceforge.net/

$ tar xvzf snort_inline-2.6.1.5.tar.gz
$ cd snort_inline-2.6.1.5
$ ./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.