SNTS - Simple Network Time Sync
Version 1.0.3 - Protocol Version 1.0
-------------------------------

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WARNING: This code is an archive from 2002, it is
not representitive of any modern development style,
experience, skill, etc. There are likely many bugs
and other issues herein. You have been warned.
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(c) 2000 Yann Ramin.  All Right Reserved.
See file COPYING for License.   BSD-Style License.


News
----

1.0.3:  Added a posibility for server to bind to other IP address

1.0.2:  Noticed that someone reported the 1.0 buffer overflow on BugTraq :)
        Dusted off code.
        Fixed a segfault if the IP address of the host can not be obtained.
        
1.0.1:  Fixes a buffer overflow which allows John Doe to
        kill sntsd/snts.
        Squelched annoying NetBSD kernel messages.


About
-----

SNTS is a simple, fast, and low overhead time syncronization
systems for LANs.  It is designed as a simple replacement for timed
with better time control and better portability (for systems without
a standard adjtime() call, such as Linux).  SNTS is split into two main
components:

	snts - The SNTS client.
	sntsd - The time server.
	
SNTS allows multiple groupings of servers on a network for independent time
management for groups or labs.  SNTS also supports multiple servers in a single
group, with elections choosing a master and other servers becoming bloated clients,
until the server should shut down where a slave will become master.
SNTS works on broadcast networks under IP
datagrams (UDP).  Security is minimal, as SNTS is designed for simplicity.
No lag negotiation is done as SNTS runs on low latency LANs, not higher latency
remote connections.

Deployment
----------

A machine which would act as the master SNTS time server should be picked.
Syncing this computer's clock via NTP is advised.  The client program 'snts'
should be distributed to each client running SNTS.  The server and client should
be run at boot time via rc files or inittab, whatever your system has.   SNTS will
then broadcast time syncs over the network and set them on the clients.
Multiple servers are supported, but through an imperfect system, they choose a master
(namely, the machine which does a normal time broadcast first) and let that machine broadcast,
while the servers act as clients and set their time to the broadcasting server.

Ok, I want some down to earth instructions
------------------------------------------

Ok, bit by bit:

I recomend building the package on the machine you wish to use as
a time server.  In the extracted directory, run

	./configure
	
Everything should go fine, otherwise check error messages and figure
out what the heck they mean.

Then give building SNTS a shot:
	
	make
	
On some systems, you may wish to use GNU make, usualy installed as
gmake.  Use whatever works.

If you wish to just test the server, do a

	make install
	
This will install snts and sntsd in /usr/local/sbin.  This would be
different if you picked a different prefix at configure time.  Distribute the
snts binary to another machine you wish to be a client (if its the same architecture).
The server and client can NOT be run on the same machine as they bind to the same port.

Power up sntsd on the server:

	/usr/local/sbin/sntsd

Power up snts on the client:

	/usr/local/sbin/snts
	
(NOTE: Despite their names, both snts and sntsd are daemons that need to be
run as root!)

In a minute or two, the clock on the client should match the clock on the server.
There is no limit to the number of clients on the wire.  A single broadcast will
serve them all.

If you want some redundancy or want each machine to have the possiblity of being
a server, then consider deploying the server to several machines or every machine.
The servers run by
themselves and through an imperfect election system, pick a master with the other
servers acting as clients until the master should cease to broadcast, where another
server will start broadcasting.  Note that in this enviroment, servers should have
the same broadcast interval as it affects the election system.


Command Line Options
--------------------

=for sntsd=

-g <#>

This option specifies a new group number.  SNTS broadcasts contain a group id header
which allows sysadmins to have multiple broadcast groups.  The client and server group id
must match.  Default: 1

-i <#>

This option sets the broadcast interval for SNTS servers.  If you only want to sync once or
twice a day, or every 5 seconds, take a look.  The # is in seconds.  Default: 240 (4 minutes)

=for snts=

-g <#>

This option specifies a new group number.  SNTS broadcasts contain a group id header
which allows sysadmins to have multiple broadcast groups.  The client and server group id
must match.  Default: 1

=for sntsd=

-a <#.#.#.#>

This option sets IP address to bind to


Known Bugs/Lacking Features
---------------------------

+ Peer-to-Peer for remote sites is not yet possible
+ A better allow/deny security feature is lacking
+ Its too simple :)

Contact
-------

Yann Ramin <atrus@stackworks.net>