HP-UX IPSec and IPFilter

Allowing Protocol 50 and Protocol 51 Traffic

 

Allowing Protocol 50 and Protocol 51 Traffic

 

When IPSec encrypts packets, it creates a new packet with a protocol

 

number of 50. When it authenticates packets, it creates a new packet

 

with a protocol number of 51.

Figure 6-5

Packet with Encrypted TCP Data

IP header Protocol # = 6

 

TCP header

 

Data

 

 

 

 

 

 

 

 

 

 

 

 

Figure 6-6

Packet with IPSec-Encrypted TCP Data

IP header Protocol # = 50

 

ESP header

 

Encrypted

 

 

 

 

 

 

 

 

 

 

 

 

IPFilter never sees the TCP packets between machine A and machine B with a protocol number of 6. These packets are encrypted (or wrapped) in a packet that has a protocol number of 50. If you configure IPFilter to block packets with protocol number 6, it lets protocol number 50 pass through. IPSec takes apart the packet and unencrypt the TCP data.

196

Chapter 6