[PLUG] Network is unreachable

[Rich Shepard]

On Fri, 16 May 2014, John Jason Jordan wrote:

> My laptop is working fine with its eth0 connection (wireless not
> enabled while at home), so I know there is no problem with the router or
> cable modem. But my desktop suddenly can't go anywhere, not even local
> pings (printers, other devices).

John,

   Every now and then one of the local hosts forgets it's part of the
network. The things to check are:

   ifconfig -a
 	Look to see if eth0 is RUNNING as well as UP

   /etc/resolv.conf
 	Make sure you have DNS server IP addresses there

   netstat -n (or just route)
 	Sometimes a system loses its kernel routing tables. You want to see
somthing like this (on this desktop host):

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use
Iface
default         router1.appl-ec 0.0.0.0         UG    1      0        0 eth0
loopback        *               255.0.0.0       U     0      0        0 lo
192.168.55.0    *               255.255.255.0   U     0      0        0 eth0

   Most commonly you'll not see any eth0 routes. The 'route' man page shows
you how to add them back in (as root, of course). Ask for help if you need
it.

Happy searching,

Rich