[ntp:questions] ntp server behind ADSL alcatel speedtouch 510 firewall not responding.

Remko Bolt marem at concepts.nl
Tue Dec 21 09:51:40 UTC 2004

Hi all,

Just set up an ntp-server on a Debian GNU/Linux host behind an alcatel 
speedtouch 510 ADSL modem which acts as a firewall and masquerades the hosts 
behind it.

- The server works fine and gets time from the outside world.
- Hosts on the local net get time from the server.

I opened up ports udp/123 and tcp/123 on the alcatel and forward them to the 
ntp-server. I have similar setup's for http and ssh which work fine.

Problem: The ntp-server is not responding to queries from the outside world. It 
is located at ntp.cluebox.org have a look.

If I telnet to :80 I get a http welcome etc. This is not so with ntp. Is there 
an easy way to check if a server is accepting connections?

Can anybody confirm that it `should' work this way with the ports set up?
Any other thoughts?


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