Subject: Re: IP-in-TCP?
To: None <tech-net@NetBSD.org>
From: der Mouse <mouse@Rodents.Montreal.QC.CA>
Date: 02/02/2005 05:56:49
> TCP keepalives are usually sent once per hour or so (did some
> googling: default on most unixes seems to be 2 hours),
RFC 1122 220.127.116.11 ("TCP Keep-Alives"): [The keep-alive] interval MUST be
configurable and MUST default to no less than two hours.
> which is enough to clean up "dead" TCP connections, but usually not
> enough to keep open over-eager NAT routers.
I once had to deal with a NAT box with a very low timeout, on the order
of three minutes. I ended up hacking an option into the kernel so I
could have it *always* do keepalives whether userland requested them or
not, and crank the interval down to about a minute. Gross, but it let
me actually use ssh through that NAT box. :-þ
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