Date: Thu, 1 Jun 2000 23:51:33 -0700 From: Pierre Chiu <pccb@yahoo.com> To: freebsd-questions@freebsd.org Cc: Dave Preece <dave.preece@kbgroup.co.nz> Subject: Re: No login day. Serious hassle. Message-ID: <15678653718.20000601235133@yahoo.com>
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Sounds like your DNS is not functioning, that's why it takes a while
due to timeout.
> Since it doesn't (as yet) involve any source code I thought I'd send this
> here and not to -hackers.
>
> Headache central. I run sshd and connect to my box through SecureCRT (an
> actually very good ssh client for Win32). Came in this morning and it
> wouldn't login. We could connect at layer 4, and some daemon and backgroud
> software I left running is fine, but not login as such. Since I mess around
> with firewalls a lot and locking myself out is not uncommon, I have a
> (shite) console connected to the serial port and can get a root login from
> here. So I got inetd up (normally disabled) and normal telnetd going and
> tried to connect again. The client connects instantly, but then takes ages
> (like, a minute) to get a login prompt. Not good, but at least I'm in.
>
> Once in, I waded through /var/log and could find nothing. Running ethereal
> onto a new telnet session showed what was happening (kinda):
>
> The three way handshake was completed and telnet opened the batting with the
> "Do suppress go ahead" command, which was acked. Then nothing for 75
> seconds. It then continues and goes through to the ack for "Login:" within
> 0.5 seconds, as to be expected. Quite why, I don't know. I've seen a similar
> problem to this before, but on that occasion I had the default router set to
> an address not on the local subnet, and fixing that solved the login
> problem.
>
> On a hunch I decided to have a look at the arp cache with arp -a, which
> didn't seem to want to complete (ctrl-C'd it), then arp -na completed and
> appeared to solve all my problems. Everything goes fine, but there is still
> a significant gap (1.5 seconds) from "do suppress go ahead" to the next
> command.
>
> So, while I am 'fixed', I still have no idea what went wrong or why. It
> seems there was some kind of corruption in the arp cache that was causing a
> timeout to happen much the same as when I did something stupid with the
> default router. Is this the case? What can I do to prevent it? And why did
> it render sshd totally unable to login?
>
> A bit confused, but protective of uptime.
> Dave :)
--
Pierre
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