vpn client access on esp ports

[eppiet]

The administrator from the site had asked me to open up the following port for vpn clients to work:

udp 500

esp 50

esp 51

Since esp is not a tcp or udp port, can I only these ports?

Thank you.

[david.benes]

You need to open:

1. UDP protocol (protocol number of UDP is 17) PORT 500 for IKE/ISAKMP

2. ESP protocol (PROTOCOL number of ESP is 50)

--

AH protocol (Authentication Header) with protocol number 51 should not be used so it is not necessary.