Recipe 19.7. Setting Up Multiple Local Time Servers

19.7.1 Problem

Your local time server is getting overwhelmed, so you need to add more servers. And you would like the additional servers to peer, so that your network hosts are always synchronized with each other.

19.7.2 Solution

In this example, two internal servers server1 and server2 synchronize with us.pool.ntp.org and with each other:

# /etc/ntp.conf for server1     driftfile  /etc/ntp.drift logfile  /var/log/ntp.log     # default access policy # this denies all ntp traffic that is not # explicitly allowed restrict default ignore     # ntp server list server pool.ntp.org server pool.ntp.org server pool.ntp.org peer server2     # allow time service from peer # but not run-time configuration changes # disable remote logging restrict server2 nomodify notrap     # allow localhost unrestricted restrict 127.0.0.0 mask 255.0.0.0

/etc/ntp.conf for server2 is identical, except the server2 entries must be replaced with server1. Configure LAN clients as described in Recipe 23.2, using the peers as the server entries:

# /etc/ntp.conf for clients driftfile  /etc/ntp.drift logfile  /var/log/ntp.log     server  server1 server  server2

19.7.3 Discussion

You can set up as many additional peers as you like; workstations can even peer with each other. For your own sanity, keep it as simple as possible. Don't try to peer with the public time servers! They have no reason to trust your servers, and you do not want to annoy time server admins. The idea behind peering is to hit the public servers as little as possible, while adequately serving the local network.

19.7.4 See Also

• The manuals for your distribution, for how to run scripts that start up with PPP

• Your local ntp documentation at /usr/share/doc/ntp-doc/html, or online at at http://www.ntp.org/documentation.html

• The ntp.org web site (http://www.ntp.org)

• The Usenet group comp.protocols.time.ntp