Testing if a particular port is open

[dilbert]

Hi all,

I just had frustrating 30 minutes with 5 different people from my service provider Virginmedia and none of these people has the slightest clue what an Internet port is and even worse they have no idea whom of their colleagues to ask.

I surely will send them an email this evening (as I cannot acces my e-mail during work).

In the meantime, here now my question:

Independently, I would like to test myself if port 5060 is open for UDP packets.

I got a few shell accounts outside of my ISP that run Linux or different BSDs. Does someone know a common program where I could send UDP packets to port 5060 of the IP address that Virginmedia assigns to me and then I would need a program on a PC within my network who reads them _if_ they get through.

Background of all this is that my VOIP phones from two different VOIP providers are offline since last Monday.
One service provider confirmed that another VOIP client is online with the same service provider Virginmedia but in a different area.

So, while I don't know how long does it take that someone from Virginmedia can tell me if their port 5060 is open for UDP, I would like to find out myself in the meantime.

[Freston]

netcat (`nc`), the swiss army knife

Let it listen on one machine, and send from another.

[dilbert]

Do you know some simple programs like ping or so where you can specify an outbound port?

[coopstah13]

you are looking for nmap

[Freston]

I can't make it much easier than `nc`

On the server:

nc -lup 5060

On the client:

echo test|nc -u $IPADDRESS 5060

nmap is also an idea:

nmap -p5060 $IPADDRESS

[dilbert]

That's great advice. Thank you.