Monday, March 24, 2014

Suricata - preparing 10Gbps network cards for IDPS and file extraction


OS used/tested for this tutorial - Debian Wheezy and/or Ubuntu LTS 12.0.4
With 3.2.0 and 3.5.0 kernel level respectively with Suricata 2.0dev at the moment of this writing.



This article consists of the following major 3 sections:
  • Network card drivers and tuning
  • Kernel specific tunning
  • Suricata.yaml configuration  (file extraction specific)

Network and system  tools:
apt-get install ethtool bwm-ng iptraf htop

Network card drivers and tuning

Our card is Intel 82599EB 10-Gigabit SFI/SFP+


rmmod ixgbe
sudo modprobe ixgbe FdirPballoc=3
ifconfig eth3 up
then (we disable irqbalance and make sure it does not enable itself during reboot)
 killall irqbalance
 service irqbalance stop

 apt-get install chkconfig
 chkconfig irqbalance off
Get the Intel network driver form here (we will use them in a second) - https://downloadcenter.intel.com/default.aspx

Download to your directory of choice then unzip,compile and install:

wget http://sourceforge.net/projects/e1000/files/ixgbe%20stable/3.18.7/ixgbe-3.18.7.tar.gz
tar -zxf ixgbe-3.18.7.tar.gz      
cd /home/pevman/ixgbe-3.18.7/src      
make clean && make && make install

Set irq affinity - do not forget to change eth3  below with the name of the network interface you are using:
 cd ../scripts/
 ./set_irq_affinity  eth3


 You should see something like this:
root@suricata:/home/pevman/ixgbe-3.18.7/scripts# ./set_irq_affinity  eth3
no rx vectors found on eth3
no tx vectors found on eth3
eth3 mask=1 for /proc/irq/101/smp_affinity
eth3 mask=2 for /proc/irq/102/smp_affinity
eth3 mask=4 for /proc/irq/103/smp_affinity
eth3 mask=8 for /proc/irq/104/smp_affinity
eth3 mask=10 for /proc/irq/105/smp_affinity
eth3 mask=20 for /proc/irq/106/smp_affinity
eth3 mask=40 for /proc/irq/107/smp_affinity
eth3 mask=80 for /proc/irq/108/smp_affinity
eth3 mask=100 for /proc/irq/109/smp_affinity
eth3 mask=200 for /proc/irq/110/smp_affinity
eth3 mask=400 for /proc/irq/111/smp_affinity
eth3 mask=800 for /proc/irq/112/smp_affinity
eth3 mask=1000 for /proc/irq/113/smp_affinity
eth3 mask=2000 for /proc/irq/114/smp_affinity
eth3 mask=4000 for /proc/irq/115/smp_affinity
eth3 mask=8000 for /proc/irq/116/smp_affinity
root@suricata:/home/pevman/ixgbe-3.18.7/scripts#
Now we have the latest drivers installed (at the time of this writing) and we have run the affinity script:
   *-network:1
       description: Ethernet interface
       product: 82599EB 10-Gigabit SFI/SFP+ Network Connection
       vendor: Intel Corporation
       physical id: 0.1
       bus info: pci@0000:04:00.1
       logical name: eth3
       version: 01
       serial: 00:e0:ed:19:e3:e1
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi msix pciexpress vpd bus_master cap_list ethernet physical fibre
       configuration: autonegotiation=off broadcast=yes driver=ixgbe driverversion=3.18.7 duplex=full firmware=0x800000cb latency=0 link=yes multicast=yes port=fibre promiscuous=yes
       resources: irq:37 memory:fbc00000-fbc1ffff ioport:e000(size=32) memory:fbc40000-fbc43fff memory:fa700000-fa7fffff memory:fa600000-fa6fffff



We need to disable all offloading on the network card in order for the IDS to be able to see the traffic as it is supposed to be (without checksums,tcp-segmentation-offloading and such..) Otherwise your IDPS would not be able to see all "natural" network traffic the way it is supposed to and will not inspect it properly.

This would influence the correctness of ALL outputs including file extraction. So make sure all offloading features are OFF !!!

When you first install the drivers and card your offloading settings might look like this:
root@suricata:/home/pevman/ixgbe-3.18.7/scripts# ethtool -k eth3
Offload parameters for eth3:
rx-checksumming: on
tx-checksumming: on
scatter-gather: on
tcp-segmentation-offload: on
udp-fragmentation-offload: off
generic-segmentation-offload: on
generic-receive-offload: on
large-receive-offload: on
rx-vlan-offload: on
tx-vlan-offload: on
ntuple-filters: off
receive-hashing: on
root@suricata:/home/pevman/ixgbe-3.18.7/scripts#

So we disable all of them, like so (and we load balance the UDP flows for that particular network card):

ethtool -K eth3 tso off
ethtool -K eth3 gro off
ethtool -K eth3 ufo off
ethtool -K eth3 lro off
ethtool -K eth3 gso off
ethtool -K eth3 rx off
ethtool -K eth3 tx off
ethtool -K eth3 sg off
ethtool -K eth3 rxvlan off
ethtool -K eth3 txvlan off
ethtool -N eth3 rx-flow-hash udp4 sdfn
ethtool -N eth3 rx-flow-hash udp6 sdfn
ethtool -C eth3 rx-usecs 1 rx-frames 0
ethtool -C eth3 adaptive-rx off

Your output should look something like this:
root@suricata:/home/pevman/ixgbe-3.18.7/scripts# ethtool -K eth3 tso off
root@suricata:/home/pevman/ixgbe-3.18.7/scripts# ethtool -K eth3 gro off
root@suricata:/home/pevman/ixgbe-3.18.7/scripts# ethtool -K eth3 lro off
root@suricata:/home/pevman/ixgbe-3.18.7/scripts# ethtool -K eth3 gso off
root@suricata:/home/pevman/ixgbe-3.18.7/scripts# ethtool -K eth3 rx off
root@suricata:/home/pevman/ixgbe-3.18.7/scripts# ethtool -K eth3 tx off
root@suricata:/home/pevman/ixgbe-3.18.7/scripts# ethtool -K eth3 sg off
root@suricata:/home/pevman/ixgbe-3.18.7/scripts# ethtool -K eth3 rxvlan off
root@suricata:/home/pevman/ixgbe-3.18.7/scripts# ethtool -K eth3 txvlan off
root@suricata:/home/pevman/ixgbe-3.18.7/scripts# ethtool -N eth3 rx-flow-hash udp4 sdfn
root@suricata:/home/pevman/ixgbe-3.18.7/scripts# ethtool -N eth3 rx-flow-hash udp6 sdfn
root@suricata:/home/pevman/ixgbe-3.18.7/scripts# ethtool -n eth3 rx-flow-hash udp6
UDP over IPV6 flows use these fields for computing Hash flow key:
IP SA
IP DA
L4 bytes 0 & 1 [TCP/UDP src port]
L4 bytes 2 & 3 [TCP/UDP dst port]

root@suricata:/home/pevman/ixgbe-3.18.7/scripts# ethtool -n eth3 rx-flow-hash udp4
UDP over IPV4 flows use these fields for computing Hash flow key:
IP SA
IP DA
L4 bytes 0 & 1 [TCP/UDP src port]
L4 bytes 2 & 3 [TCP/UDP dst port]

root@suricata:/home/pevman/ixgbe-3.18.7/scripts# ethtool -C eth3 rx-usecs 0 rx-frames 0
root@suricata:/home/pevman/ixgbe-3.18.7/scripts# ethtool -C eth3 adaptive-rx off

Now we doublecheck and run ethtool again to verify that the offloading is OFF:
root@suricata:/home/pevman/ixgbe-3.18.7/scripts# ethtool -k eth3
Offload parameters for eth3:
rx-checksumming: off
tx-checksumming: off
scatter-gather: off
tcp-segmentation-offload: off
udp-fragmentation-offload: off
generic-segmentation-offload: off
generic-receive-offload: off
large-receive-offload: off
rx-vlan-offload: off
tx-vlan-offload: off

Ring parameters on the network card:

root@suricata:~# ethtool -g eth3
Ring parameters for eth3:
Pre-set maximums:
RX:             4096
RX Mini:        0
RX Jumbo:       0
TX:            4096
Current hardware settings:
RX:             512
RX Mini:        0
RX Jumbo:       0
TX:             512


We can increase that to the max Pre-set RX:

root@suricata:~# ethtool -G eth3 rx 4096

Then we  have a look again:

root@suricata:~# ethtool -g eth3
Ring parameters for eth3:
Pre-set maximums:
RX:             4096
RX Mini:        0
RX Jumbo:       0
TX:             4096
Current hardware settings:
RX:             4096
RX Mini:        0
RX Jumbo:       0
TX:             512

Making network changes permanent across reboots


On Ubuntu for example you can do:
root@suricata:~# crontab -e

Add the following:
# add cronjob at reboot - disbale network offload
@reboot /opt/tmp/disable-network-offload.sh

and your disable-network-offload.sh script (in this case under /opt/tmp/ ) will contain the following:



#!/bin/bash
ethtool -K eth3 tso off
ethtool -K eth3 gro off
ethtool -K eth3 ufo off
ethtool -K eth3 lro off
ethtool -K eth3 gso off
ethtool -K eth3 rx off
ethtool -K eth3 tx off
ethtool -K eth3 sg off
ethtool -K eth3 rxvlan off
ethtool -K eth3 txvlan off
ethtool -N eth3 rx-flow-hash udp4 sdfn
ethtool -N eth3 rx-flow-hash udp6 sdfn
ethtool -C eth3 rx-usecs 1 rx-frames 0
ethtool -C eth3 adaptive-rx off


with:
chmod 755 disable-network-offload.sh
To make sure you have the ixgbe module always loaded at boot time you can add "ixgbe" to the  /etc/modules file.

Kernel specific tunning


Certain adjustments in parameters in the kernel can help as well :

sysctl -w net.core.netdev_max_backlog=250000
sysctl -w net.core.rmem_max=16777216
sysctl -w net.core.rmem_default=16777216
sysctl -w net.core.optmem_max=16777216


Making kernel changes permanent across reboots


example:
echo 'net.core.netdev_max_backlog=250000' >> /etc/sysctl.conf

reload the changes:
sysctl -p

OR for all the above adjustments:

echo 'net.core.netdev_max_backlog=250000' >> /etc/sysctl.conf
echo 'net.core.rmem_max=16777216' >> /etc/sysctl.conf
echo 'net.core.rmem_default=16777216' >> /etc/sysctl.conf
echo 'net.core.optmem_max=16777216' >> /etc/sysctl.conf
sysctl -p


Suricata.yaml configuration  (file extraction specific)

As of Suricata 1.2  - it is possible to detect and extract/store over 5000 types of files from HTTP sessions.

Specific file extraction instructions can also be found in the official page documentation.

The following libraries are needed on the system running Suricata :
apt-get install libnss3-dev libnspr4-dev

Suricata also needs to be compiled with file extraction enabled (not covered here).

In short in the suriacta.yaml, those are the sections below that can be tuned/configured and affect the file extraction and logging:
(the bigger the mem values the better on a busy link )


  - eve-log:
      enabled: yes
      type: file #file|syslog|unix_dgram|unix_stream
      filename: eve.json
      # the following are valid when type: syslog above
      #identity: "suricata"
      #facility: local5
      #level: Info ## possible levels: Emergency, Alert, Critical,
                   ## Error, Warning, Notice, Info, Debug
      types:
        - alert
        - http:
            extended: yes     # enable this for extended logging information
        - dns
        - tls:
            extended: yes     # enable this for extended logging information
        - files:
            force-magic: yes   # force logging magic on all logged files
            force-md5: yes     # force logging of md5 checksums
        #- drop
        - ssh


For file store to disk/extraction:
   - file-store:
      enabled: yes       # set to yes to enable
      log-dir: files    # directory to store the files
      force-magic: yes   # force logging magic on all stored files
      force-md5: yes     # force logging of md5 checksums
      #waldo: file.waldo # waldo file to store the file_id across runs


 stream:
  memcap: 32mb
  checksum-validation: no      # reject wrong csums
  inline: auto                  # auto will use inline mode in IPS mode, yes or no set it statically
  reassembly:
    memcap: 128mb
    depth: 1mb                  # reassemble 1mb into a stream
  
depth: 1mb , would mean that in one tcp reassembled flow, the max size of the file that can be extracted is just about 1mb.

Both stream.memcap and reassembly.memcap (if reassembly is needed) must be big enough to accommodate the whole file on the fly in traffic that needs to be extracted PLUS any other stream and reassembly tasks that the engine needs to do while inspecting the traffic on a particular link.

 app-layer:
  protocols:
....
....
     http:
      enabled: yes
      # memcap: 64mb

The default limit for mem usage for http is 64mb   , that could be increased , ex - memcap: 4GB -  since HTTP is present everywhere and a low memcap on a busy HTTP link would limit the inspection and extraction size ability.

       libhtp:

         default-config:
           personality: IDS

           # Can be specified in kb, mb, gb.  Just a number indicates
           # it's in bytes.
           request-body-limit: 3072
           response-body-limit: 3072

The default values above control how far the HTTP request and response body is tracked and also limit file inspection. This should be set to a much higher value:

        libhtp:

         default-config:
           personality: IDS

           # Can be specified in kb, mb, gb.  Just a number indicates
           # it's in bytes.
           request-body-limit: 1gb
           response-body-limit: 1gb

 or 0 (which would mean unlimited):

       libhtp:

         default-config:
           personality: IDS

           # Can be specified in kb, mb, gb.  Just a number indicates
           # it's in bytes.
           request-body-limit: 0
           response-body-limit: 0

and then of course you would need a rule loaded(example):
alert http any any -> any any (msg:"PDF file Extracted"; filemagic:"PDF document"; filestore; sid:11; rev:11;)



That's it.
























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