0000371: ntpd will stop working when network interfaces change

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Date Submitted

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0000371

ClearOS

app-ntp - NTP Server

public

2011-10-24 00:29

2013-08-14 19:12

Reporter

devferret

Assigned To

user2

Priority

normal

Severity

minor

Reproducibility

always

Status

closed

Resolution

fixed

Platform

OS Version

Product Version

Target Version

6.5.0 Beta 1

Fixed in Version

6.5.0 Beta 1

Summary

0000371: ntpd will stop working when network interfaces change

Description

My external interface uses pppoe; if that ever goes down and up again (which it does regularly, grrrr. ADSL grrr.) ntp stops being able to communicate with any external servers.

The problem is fully described here:
http://lists.ntp.org/pipermail/questions/2005-August/006332.html [^]

ntp.org admits the issue here: http://support.ntp.org/bin/view/Support/ConfiguringNTP#Section_6.13. [^]
> Currently, ntpd does not rescan the network interfaces after it has started.
> If you are have a dynamic IP (use DHCP), this means ntpd will no longer be
> able to communicate with "outside" sources after your IP changes.

My hack for fixing it is below. It's not ideal... in particular the init scripts start ntpd with -g which will cause a step-jump in the time; in this case ntpd should be restarted with -x so the time is slewed. Also not sure if /etc/ppp/ip-up.local is the best place.

/etc/ppp/ip-up.local:

/usr/share/system/scripts/firewall-up $1
# gid -- ntpd can't handle changing interface, so restart
if [[ $1 == ppp0 && -x /etc/init.d/ntpd ]] ; then
logger "ppp0 up -- restarting ntpd"
/etc/init.d/ntpd condrestart
fi

Finally, I think this means that modifying any network interfaces via the webconfig will also cause this to happen (for the modified interface). Not sure if ntpd already gets restarted in that case.

Additional Information

Sample logs... ADSL goes down, ntpd starts erroring:

Oct 11 11:33:22 office pppd[21695]: Connection terminated.
Oct 11 11:33:22 office pppd[21695]: Modem hangup
Oct 11 11:33:27 office pppd[21695]: Exit.
Oct 11 11:33:27 office pppoe[21696]: read (asyncReadFromPPP): Session 4185: Input/output error
Oct 11 11:33:27 office pppoe[21696]: Sent PADT
Oct 11 11:33:27 office adsl-connect: ADSL connection lost; attempting re-connection.
Oct 11 11:33:29 office adsl-stop: Killing pppd
Oct 11 11:33:29 office adsl-stop: Killing adsl-connect
Oct 11 11:33:33 office ntpd[21887]: sendto(64.34.185.196) (fd=24): Invalid argument

That last message will repeat each time ntpd tries to talk to any peer.

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Notes
(0000969) user2 2013-08-02 11:19	Source Code Changelog --------------------------------------------------- - Added network event to ntp to handle restarts on dynamic IPs [tracker 0000371] File Changes --------------------------------------------------- Details: http://code.clearfoundation.com/svn/revision.php?repname=ClearOS&rev=6298 [^] U webconfig/apps/ntp/trunk/deploy/info.php U webconfig/apps/ntp/trunk/packaging/app-ntp.spec A webconfig/apps/ntp/trunk/packaging/network-connected-event

Issue History
Date Modified	Username	Field	Change
2011-10-24 00:29	devferret	New Issue
2011-10-24 12:31	user2	Status	new => confirmed
2013-02-02 11:02	user2	Target Version	=> 6.4.0 Beta 2
2013-02-21 20:00	user2	Target Version	6.4.0 Beta 2 => 6.4.0
2013-03-14 11:56	user2	Target Version	6.4.0 => 6.4.0 Updates
2013-07-29 13:57	user2	Target Version	6.4.0 Updates => 6.5.0 Beta 1
2013-08-02 11:19	user2	Checkin
2013-08-02 11:19	user2	Note Added: 0000969
2013-08-02 11:19	user2	Status	confirmed => resolved
2013-08-02 11:19	user2	Fixed in Version	=> 6.5.0 Beta 1
2013-08-02 11:19	user2	Resolution	open => fixed
2013-08-02 11:19	user2	Assigned To	=> user2
2013-08-14 19:12	user2	Status	resolved => closed

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