Help starting NTP daemon with Slackware

Mike Bilow mikebw at colossus.bilow.com
Fri Jun 23 17:13:08 EDT 2000


This is not going to work.  NTP relies upon exchanges involving port 123.  
With restrictions as draconian as you descrive, moving precise time
information would be very difficult.

There are several approaches.  The straightforward solution would be to
set up a local Stratum 1 time server, referenced to some hardware clock.  
These can be done for surprisingly little money, either with GPS receivers
(http://www.tapr.org/tapr/html/tac2.html) or even ordinary sound cards
(http://www.rossi.com/other.html).

One option you might consider is using HTTP timestamps for external
synchronization.  This would be less accurate than NTP, but it would get
through your firewall.  You could easily write a simple daemon that looked
like a hardware clock to the NTP daemon and checked HTTP timestamps.  
Obviously, the accuracy of the system to which you are referring would be
critical, so you would want to use a web server that is locked by NTP.

-- Mike


On 2000-06-20 at 19:44 -0400, Scott Ehrlich wrote:

> We have a Slackware 7 server which we want to use as the central time
> server for the LAN.   We also have set up a lot of security, permitting
> only ssh, smtp, and http.   There is no firewall.   I'm trying to figure
> out how to start an NTP daemon so the other servers can keep their
> respective times correct.


-
Subcription/unsubscription/info requests: send e-mail with
"subscribe", "unsubscribe", or "info" on the first line of the
message body to discuss-request at blu.org (Subject line is ignored).



More information about the Discuss mailing list