Snort Intergration¶

Overview¶

There are two options can send alert to OS-Ken controller. The Option 1 is easier if you just want to demonstrate or test. Since Snort need very large computation power for analyzing packets you can choose Option 2 to separate them.

[Option 1] OS-Ken and Snort are on the same machine

      +------------------------+
      |      unixsock          |
      |    OS-Ken  ==  snort   |
      +----eth0-----eth1-------+
             |       |
+-------+   +----------+   +-------+
| HostA |---| OFSwitch |---| HostB |
+-------+   +----------+   +-------+

The above depicts OS-Ken and Snort architecture. OS-Ken receives Snort alert packet via Unix Domain Socket . To monitor packets between HostA and HostB, installing a flow that mirrors packets to Snort.

[Option 2] OS-Ken and Snort are on the different machines

          +---------------+
          |    Snort     eth0--|
          |   Sniffer     |    |
          +-----eth1------+    |
                 |             |
+-------+   +----------+   +-----------+
| HostA |---| OFSwitch |---| LAN (*CP) |
+-------+   +----------+   +-----------+
                 |             |
            +----------+   +-------------+
            |  HostB   |   |   OS-Ken    |
            +----------+   +-------------+

*CP: Control Plane

The above depicts OS-Ken and Snort architecture. OS-Ken receives Snort alert packet via Network Socket . To monitor packets between HostA and HostB, installing a flow that mirrors packets to Snort.

Installation Snort¶

Snort is an open source network intrusion prevention and detectionsystem developed by Sourcefire. If you are not familiar with installing/setting up Snort, please referto snort setup guides.

http://www.snort.org/documents

Configure Snort¶

The configuration example is below:

• Add a snort rules file into /etc/snort/rules named Myrules.rules

  alert icmp any any -> any any (msg:"Pinging...";sid:1000004;)
  alert tcp any any -> any 80 (msg:"Port 80 is accessing"; sid:1000003;)
  

• Add the custom rules in /etc/snort/snort.conf

  include $RULE_PATH/Myrules.rules
  

Configure NIC as a promiscuous mode.

$ sudo ifconfig eth1 promisc

Usage¶

[Option 1]

1. Modify the simple_switch_snort.py:

   socket_config = {'unixsock': True}
   # True: Unix Domain Socket Server [Option1]
   # False: Network Socket Server [Option2]
   

2. Run OS-Ken with sample application:

   $ sudo osken-manager os_ken/app/simple_switch_snort.py
   

The incoming packets will all mirror to port 3 which should be connect to Snort network interface. You can modify the mirror port by assign a new value in the self.snort_port = 3 of simple_switch_snort.py

3. Run Snort:

   $ sudo -i
   $ snort -i eth1 -A unsock -l /tmp -c /etc/snort/snort.conf
   

4. Send an ICMP packet from HostA (192.168.8.40) to HostB (192.168.8.50):

   $ ping 192.168.8.50
   

5. You can see the result under next section.

[Option 2]

1. Modify the simple_switch_snort.py:

   socket_config = {'unixsock': False}
   # True: Unix Domain Socket Server [Option1]
   # False: Network Socket Server [Option2]
   

2. Run OS-Ken with sample application (On the Controller):

   $ osken-manager os_ken/app/simple_switch_snort.py
   

3. Run Snort (On the Snort machine):

   $ sudo -i
   $ snort -i eth1 -A unsock -l /tmp -c /etc/snort/snort.conf
   

4. Run pigrelay.py (On the Snort machine):

   $ sudo python pigrelay.py
   

This program listening snort alert messages from unix domain socket and sending it to OS-Ken using network socket.

You can clone the source code from this repo. https://github.com/John-Lin/pigrelay

5. Send an ICMP packet from HostA (192.168.8.40) to HostB (192.168.8.50):

   $ ping 192.168.8.50
   

6. You can see the alert message below:

   alertmsg: Pinging...
   icmp(code=0,csum=19725,data=echo(data=array('B', [97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 97, 98, 99, 100, 101, 102, 103, 104, 105]),id=1,seq=78),type=8)
   
   ipv4(csum=42562,dst='192.168.8.50',flags=0,header_length=5,identification=724,offset=0,option=None,proto=1,src='192.168.8.40',tos=0,total_length=60,ttl=128,version=4)
   
   ethernet(dst='00:23:54:5a:05:14',ethertype=2048,src='00:23:54:6c:1d:17')
   
   
   alertmsg: Pinging...
   icmp(code=0,csum=21773,data=echo(data=array('B', [97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 97, 98, 99, 100, 101, 102, 103, 104, 105]),id=1,seq=78),type=0)
   
   ipv4(csum=52095,dst='192.168.8.40',flags=0,header_length=5,identification=7575,offset=0,option=None,proto=1,src='192.168.8.50',tos=0,total_length=60,ttl=64,version=4)