Re: Not connecting over LAN
Allegedly, on or about 19 November 2013, Beartooth sent:
I have several machines on a LAN (and a KVM switch that I use
when they're all functioning). Most are online over ethernet via a
Linksys modem running DD-WRT v24-sp2 (10/10/09)micro; and I can
normally ssh from any to any.
But at present there are two on which ssh in either direction
gets only Connection refused. Both are running F18, fully updated.
What is likely to be the glitch, and how can I fix it?
Reboot the things in the middle (the Linksys modem & KVM switch) that'd
be my first step. Perhaps shutdown, pull out the power, and restart
completely fresh. Swap some network cables around between different
sockets. Check that ssh daemon is running, firewalls have suitable
holes in them, and SELinux allows sshd.
In operation, if you see network indicator lights madly flicking on and
off, for no apparent reason, that can be a network "flapping." Or, if
you see a light that's permanently on, even when it shouldn't be (e.g.
it should flicker when there's traffic, go out when equipment is off).
They could be temporary glitches that'll be fixed by a hard reset, it
could be permanent component failure.
I've had to replace several network switches, over the years, as they've
crapped out for one reason or another. There's been simple power supply
pack failures. And they span between buildings, with a fairly long UTP
cable, so I suspect EMR picked up from lightning storms may zap some of
the circuitry. And since no affordable network devices bother to put
isolating transformers on inputs and outputs (galvanic isolation), any
grounding differences between buildings are probably stressing input
circuits.
Though one managed to survive a rather bad mains active to earth leak,
for a very long time (wildlife in the ceiling attacking the lighting
wiring - on a couple of occasions I've heard rustles in the ceiling,
brief lighting dims and a nasty electric-chair buzzing sounds, animal
screeching then running like mad through the roof, which has been
somewhat amusing to hear the buggers get their comeuppance). And I've
still got the copper wiring spot-welded to the screwdriver that I
experimentally placed between two lots of earth wiring. I'm glad I
mistrusted someone else's electrical work enough to test it, rather than
put my fingers on earth wiring expecting it to be safe. I wasn't
expecting that rather extreme reaction, though.
That's my situation (sporadic hardware failures), but it may shed light
on someone else having equipment failures.
--
[tim@localhost ~]$ uname -rsvp
Linux 3.8.13-100.fc17.x86_64 #1 SMP Mon May 13 13:36:17 UTC 2013 x86_64
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