Hi hop this is not a silly question

I am trying to configure a iptable firewall and it has an entry as below

-A INPUT -p 51 -j ACCEPT
-A INPUT -p 50 -j ACCEPT

Why do I need to allow these protocols?

Thanks and Regards

http://compnetworking.about.com/od/t...ports_gl50.htm

a fast google search could of provided you that exact link.

You don't say on what type of box this is or usage, but I don't have those rules accepted on either server or laptop and everything works fine.

Hi Guys thank you

I did googled but the answers are not what I was looking for and I found this below link
http://www.iana.org/assignments/prot...-numbers.xhtml
and this tells

50 ESP Encap Security Payload [RFC4303]
51 AH Authentication Header [RFC4302]

and Lleb you link says

50 TCP UDP Remote Mail Checking Protocol (RMCP)RFC 1339
51 TCP UDP IMP Logical Address Maintenance

I am totally confused

This was our old firewall and this and using NAT forwared our support to attend customer support (login to customer sites) and Filtering, and this was used to forward Mail traffic to our mail relay once but not any more.

This a Redhat 6.3 (64bit) box

Thanks and Regards

The -p defined the protocol, not the port. Those two protocols allow VPN access. You most likely had s2s VPNs setup.

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good catch O.o

Hi O.o thanks you just the information that I was looking for, yes we had a tunnel to one of our customer sites

Thank you guys for helping

Best Of regards