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| Subject: | Re: VPN protocols |
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| Date: | Wed, 22 Dec 2004 10:48:57 -0700 |
On Wed, 22 Dec 2004 09:04:16 -0800, John Forristel (SunGard-Chico) <John.Forristel@sungardbi-tech.com> wrote:
GRE and ESP are protocols, not ports, so they are transported through on configured ports. In Cisco, you permit gre and esp through for the VPN traffic.
No, they are not transported on configured ports. They are transported via IP, and your IP stack is informed of this by the 10th byte of the IP header. In tcpdump parlance: (ip[9] = 47) GRE (ip[9] = 50) ESP -- GDB has a 'break' feature; why doesn't it have 'fix' too?
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