[Spread-users] Unable to send message to machine on LAN

John Schultz jschultz at spreadconcepts.com
Wed Sep 2 13:22:07 EDT 2009

One thing to check is whether or not there are any firewalls  
intervening between guest_a and host_b that allows common services  
(e.g. - ping, http, ssh, etc.) but denies random UDP communication on  
higher ports (e.g. - 4803 and 4804).

You can also try playing with the spsend and sprecv programs to see if  
UDP traffic can flow the way Spread uses it on the appropriate ports.   
First, get the newest trunk version from the spread.org svn  
repository, or edit daemon/Makefile and make the following change:

Index: Makefile.in
--- Makefile.in	(revision 435)
+++ Makefile.in	(working copy)
@@ -88,7 +88,7 @@
  	$(LD) -o $@ s.o alarm.o data_link.o events.o memory.o $(LDFLAGS) $ 

  sprecv$(EXEEXT): r.o alarm.o data_link.o
-	$(LD) -o $@ r.o alarm.o data_link.o $(LDFLAGS) $(LIBS)
+	$(LD) -o $@ r.o alarm.o data_link.o events.o memory.o $(LDFLAGS) $ 

  	rm -f *.lo *.tlo *.to *.o *.a *.dylib $(TARGETS) spsimple_user

Then build sprecv and spsend in the daemon directory like so:

make sprecv spsend

You can then use these programs to test if communications can flow  
between guest_a and host_b through the addresses and ports that you've  

host_b> ./sprecv -p 4803

guest_a> ./spsend -p 4803 -a

If that works, then switch the receiver and sender between host_b and  
guest_a to make sure the communication is bi-directional.  You may  
also want to test that port 4804 works and you may try the broadcast  
addresses as well.  If all that works, then I don't see any obvious  
reason why your setup should not work, but I am not a virtualization  
guru in the least.


John Lane Schultz
Spread Concepts LLC
Phn: 301 830 8100
Cell: 443 838 2200

On Sep 2, 2009, at 12:36 PM, Sandeep Agarwal wrote:


I have 2 machines (hosts) with vmware installed. Each machine has one
guest OS installed on it.
Network setup:

host_a :
host_b :

guest_a : # Guest OS on host_a
guest_b : # Guest OS on host_b

guest_a can ping and access services (ssh, http) from host_b,
similarly guest_b can communicate with host_a.

I am first trying to setup Spread in such a way that guest from any
one host should be able to send message to other host, i.e. guest_a
should be able to send message to host_b.

Spread config on guest_a:

Spread_Segment {

Spread_Segment {

host_a and host_b are having exact config file and the spread segments
are also listed in the above order.

with this setup host_a and guest_a can communicate but no message is
delivered to host_b.

If I remove spread segment for from host_a and restart
the daemon host_a and host_b can communicate but I am not able to
configure spread such that all the three machines can communicate.

Suggestions ?

Is spread treating host_a as multi-homed host with two networks and and how does it effects the spread
communication ?

Can anyone also point me to some spread documentation that explains
the spread basics and configuration in details.



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