Re: Nat+Iptables+Tcp Keepalive Problem

[Emiliano Romero <emilianoromero@gmail.com>]

Jozsef Kadlecsik escribió:
> The TCP keepalived packet in the output above is invalid: it's sequence 
> number is wrong.
> 
> Best regards,
> Jozsef

Thanks for your reply Jozsef. After your reply I look at RFC 1122, It say:
"Some TCP implementations, however, have included a keep-alive 
mechanism.  To confirm that an idle connection is still active, these 
implementations send a probe segment designed to elicit a response from 
the peer TCP.  Such a segment generally contains SEG.SEQ = SND.NXT-1"
..."so that this SEG.SEQ will be outside the window.  Therefore, the 
probe causes the receiver to return an acknowledgment segment"

When I try with a linux box sending TCP KA, I see that this sets the ACK 
flag on TCP KeepAlive and that works correctly. I think that my remote 
equipments (GPRS Modems) are making TCP KA is the wrong way. Or maybe 
the GPRS Service Provider are touching my packets.

Thanks Again.

Regards
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