kern/123881: Turning on TCP blackholing causes slow localhost connections

[Kris Kennaway]

On Thu, May 22, 2008 at 02:10:04PM +0000, Maxim Konovalov wrote:
> The following reply was made to PR kern/123881; it has been noted by GNATS.
> 
> From: Maxim Konovalov <maxim at macomnet.ru>
> To: Tom Karpik <tom at tomkarpik.com>
> Cc: bug-followup at freebsd.org
> Subject: Re: kern/123881: Turning on TCP blackholing causes slow localhost
>  connections
> Date: Thu, 22 May 2008 17:40:35 +0400 (MSD)
> 
>  > Turning on TCP blackholing (sysctl net.inet.tcp.blackhole=2) seems
>  > to make connecting to some local services very slow.
>  >
>  > Example: telnet localhost 25 (default local Sendmail daemon after
>  > fresh installation of FreeBSD)
>  >
>  > Sendmail responds with its greeting string right away if blackholing
>  > is off. If it's turned on, it takes about 8-12 seconds for the
>  > greeting to show up.
>  
>  Just an idea -- sendmail tries to use ident service and just timeouts
>  on it due to tcp blackholing.  To check this idea try to run e.g.
>  inetd(8) auth service.

Failing that, use tcpdump to work out what is going on.

Kris

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