[Spread-users] WAN with internal and external IPs

Jacob Green jgreen at spreadconcepts.com
Tue May 2 16:44:15 EDT 2006

Spread is designed to work such that all daemons can directly access all the
other daemons in the system using unicast.  Therefore, in general, Spread
does not work when you have multiple segments and private IPs as usually
such segmented private IPs cannot access one another.

However, you can hack together a somewhat crippled solution using port
forwarding for a demonstration.  The solution is crippled in the sense that
you need a public IP per daemon, which usually means you can have only one
such daemon per segment since the router often only has one static IP.
Effectively you have the router with the public IP port forward on ports P,
P+1 and P+2 (where P is the port you configure the segment to use) to the
daemon with the private IP.

Example Spread Config File (1 PC per site):

Spread_Segment {
	Home # (home router's static IP)

Spread_Segment {
	Work # (work router's static IP)

Then port forward on the home router ( to your internal machine
(192.168.x.x) ports 4803, 4804, 4805 and port forward on your work router
( to your other internal machine (192.168.x.x) ports 9999, 10000,
10001.  How you do this is router dependent.  Finally, you need to configure
the private machines network cards to also have the public IPs as interfaces
-- how you do this is OS specific but can be done on most systems.

Then when you run the daemons tell them their name in the config file by

./spread -n Home


./spread -n Work

respectively.  It is a little bit hairy and we usually don't recommend
trying to run a real system this way, but it might work for your situation.


Jacob Green
Spread Concepts LLC.
v: 301-498-3233
e: jgreen at spreadconcepts.com
w: http://www.spreadconcepts.com

-----Original Message-----
Sent: Tuesday, May 02, 2006 3:47 PM
To: spread-users at lists.spread.org
Subject: [Spread-users] WAN with internal and external IPs


  I am a contractor working for the navy. Developing a common data model and
a way to share the info. Was looking at spread for the messaging part of it.
Trying to test it out but I am having problems with configuration. Doing a
run between office and home. Both sites have a single static ip, a router
and pcs behind. Can't figure it out. Saw in the user's guide a footnoted
reference to this problem. BTW, this is probably not going to be a real
concern for the actual product but if I can't show it to my boss, not going
to happen. Thanks for any help.


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