Network tools

• Network utilities. Some may be disabled on your setup.

Linux / UNIX

• To see IP address:
  1. ifconfig (older tool) (not on DCU server)
  2. ip (newer).
  3. Usage: How to find your IP address

• To query who owns domain, does host exist
  1. dig (domain or host)
  2. host (like dig but returns less info)
  3. nslookup (hostname)
  4. netstat

  5. whois (domain)
     • whois dcu.ie reveals DCU nameservers (for external users):

       Name Server: ns-105.awsdns-13.com
       Name Server: ns-1250.awsdns-28.org
       Name Server: ns-2005.awsdns-58.co.uk
       Name Server: ns-870.awsdns-44.net
       

       We use Amazon Web Services DNS service.

• Other tools:
  1. ping (send packet to see if host is up) (think only works locally at DCU)
     • To just ping once:

        ping -c 1 hostname 

  2. traceroute (query route to host)
     Think not working since DCU changed to Amazon services.

Windows

• Windows command line
  • Reference

• To see your IP address:
  1. ipconfig
     • ipconfig /all shows DNS servers.
     • How to find your IP address

• Tools:
  1. nslookup
  2. ping
  3. pathping
  4. netstat
  5. tracert

Traceroute

• It used to be easy to use traceroute to see routes to distant servers.
• Seems to be getting harder to use it. Traceroute blocked by firewalls / never returns.
• Search for traceroute online lookup.

• Comms from DCU to UCD go through HEAnet.
• Here is an old traceroute from DCU to UCD, before Amazon was contracted:

  $ traceroute www.ucd.ie
  traceroute to www.ucd.ie (193.1.172.140), 30 hops max, 40 byte packets
   1  router-11.computing.dcu.ie (136.206.11.254)  0.383 ms  0.247 ms  0.330 ms
   2  136.206.13.254 (136.206.13.254)  0.369 ms  0.303 ms  0.344 ms
   3  cisdcu.dcu.ie (136.206.3.1)  0.813 ms  0.670 ms  0.362 ms
   4  kuiper-gige2-1.dcu.access.hea.net (193.1.196.189)  1.356 ms  1.098 ms  1.508 ms
   5  hyperion-gige4-2.cwt.core.hea.net (193.1.194.68)  1.558 ms  1.602 ms  0.990 ms
   6  ar1-cwt-gige6-1.hea.net (193.1.195.177)  1.824 ms  1.466 ms  1.918 ms
   7  * * *
   8  nore-r2-vlan-13.ucd.ie (193.1.145.10)  2.667 ms  2.737 ms  2.647 ms
   9  clarion.ucd.ie (193.1.172.140)  2.299 ms  2.573 ms  2.339 ms