Network debugging guide

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Network debugging guide for Free Geek Vancouver

Common/semi-common issues

Network not working

Symptoms

Nothing works from one computer, other computers work fine. Or all the computers in an area are down. When attempting to debug always make sure the problem occurs on at least one other computer which is in a different room (actually a different switch).

Resolution
  • Ensure network cable is plugged into machine
  • Ensure the cable is plugged into a switch which is turned on
  • Ensure the switch is connected to the rest of the network
  • Reboot the switch

Internet connection down

Symptoms

Unable to visit an external website such as http://www.google.com/ or http://www.cbc.ca/. Internal websites such as http://fgdb.shop.lan/ and http://tasks.shop.lan/ are still available.

Resolution
  • Ensure the cable modem has power and appropriate lights on (FILLIN).
  • Reboot the router (nut)

Rebooting the router will disrupt all internal traffic and may take a couple of cycles before the internet works, be sure to give enough time after rebooting before testing again (5 minutes generally).

Generally slow/very slow network

Symptoms

Both internal (http://fgdb.shop.lan/) and external websites such as http://www.google.com/ or http://www.cbc.ca/ load slowly or intermittently. In the console running a command such as ping fir.shop.lan returns a time larger than 1-2 ms (such as 6ms).

Resolution

This has generally been caused by a switch having some difficulties, rebooting the switch generally fixes it. The two most likely switches are the D-Link switch in the back of the rack (pull the Keyboard/monitor out the front of the rack and then you can get access to the power cable from the rear of the rack) and the matching D-Link switch on top of the cupboards in the mezzanine. ping fir.shop.lan should usually have a time of less than 1ms (such as time=0.735ms) after rebooting the switch.

DHCP Down

Symptoms

After rebooting any terminal it will not allow any user login. Freshly booted build machines will not show an active network connection. Running sudo dhclient eth0 doesn't show a IP address assigned.

Resolution

Reboot the router. If that does not fix the issue then verify switches between the test machine and the router are powered on and working correctly.

One or more internal services down

Symptoms

External websites work, an internal website or multiple internal websites do not work.

Resolution

This has generally been caused by a VM server locking up: Check the console of fir, teak and elm. If one of them is saying something about a call trace and/or process blocked then that system is locked up. Ideally copy down the information on the screen and then reboot it.

Installations unable to find apt.shop.lan

Symptoms

During installation an error pops up saying unable to connect to apt.shop.lan or such

Resolution
  • Log in to alder
  • run: sudo service apt-cacher-ng restart

Occasionally this service crashes and needs a manual boot.

No incoming calls

Symptoms

People are unable to call in to Free Geek. Outgoing calls may still work. running sudo asterisk -vr on copper.shop.lan and then sip show peers does not show an IP address beside TrunkPrimary/...

Resolution

This is generally caused by our registration timing out with our provider, to fix:

  • ssh copper.shop.lan
  • sudo service asterisk restart

This could also be caused by the phones which usually ring being turned off or frozen.

External Web sites down

Symptoms

People from the outside unable to access Free Geek such as wiki.freegeekvancouver.org or tasks.freegeekvancouver.org Error 502 Bad Gateway nginx

Resolution
  • ssh nut.shop.lan
  • sudo service nginx restart or stop and start