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I'm trying to use GeekTool (Mac pref pane... basically just embeds output of a shell command/script on the desktop... http://lifehacker.com/#!244026/geek-to-live--monitor-your-mac-and-more-with-geektool) to monitor a a remote machines/server, and I'm having some trouble determining how best to check if a machine is up/down.

I'm using no-ip as a free dns re-direct... but this only helps me with the public IP of the router. The machine I want is behind the router and thus isn't able to be "ping"ed directly.

I have port forwarding set up for port 8080 which leads to the machine I want. Is there a way to essentially ping through port 8080 to see if the machine is up and running? I tried telnet, but this apparently doesn't work (as far as output) in GeekTool. I'm running a website at 8080, so I guess I just want to know if/when it goes down.

Thanks in advance... if I can provide more clarification let me know.

(figured out my problem... see below)

loeschg
  • 581

4 Answers4

43

To check a specific port, you can use telnet:

telnet 127.0.0.1 8080

(The port follows the IP / hostname with a space, not a colon.)

If you get an immediate error, then the port is not available. If telnet hangs, then you have successfully connected to the port. Ctrl + C to kill telnet, then.

This may or may not help with the port forwarding issue, though. It just gets you to that IP and port.

Gareth
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10

Theres is hping utility that allows you to ping TCP ports. This is also available via homebrew (brew install hping).

backdrift.org gives a simple instructions on how to use hping for this purpose

$ hping -S -p 80 google.com
HPING google.com (eth0 66.249.92.104): S set, 40 headers + 0 data bytes
len=44 ip=66.249.92.104 ttl=47 id=10442 sport=80 flags=SA seq=0 win=5720 rtt=97.7 ms
len=44 ip=66.249.92.104 ttl=47 id=40838 sport=80 flags=SA seq=1 win=5720 rtt=97.7 ms
len=44 ip=66.249.92.104 ttl=47 id=64607 sport=80 flags=SA seq=2 win=5720 rtt=97.7 ms
len=44 ip=66.249.92.104 ttl=47 id=10443 sport=80 flags=SA seq=3 win=5720 rtt=97.7 ms
^C
--- google.com hping statistic ---
4 packets transmitted, 4 packets received, 0% packet loss
round-trip min/avg/max = 97.7/97.7/97.7 ms
Sean Allred
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Juha Palomäki
  • 555
0

You could use wget, curl etc. to check that the website is responding.

Neil
  • 889
0

Telnet gets the job done, but I'm unable to integrate that with GeekTool. I ended up doing a mysqladmin ping to the remote machine. The website has a db backend, so this (more-or-less) returns the info I'm looking for. Thanks for all the help!

loeschg
  • 581