RE: UDP Packet Source Address

Bind the java program to only one IP address instead of using all. "*" 


Chris Bipes
Information Services Director
CrossCheck, Inc.

-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx
[mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Larry Bolhuis
Sent: Thursday, September 08, 2005 9:26 AM
To: Midrange Systems Mailing List
Subject: UDP Packet Source Address

Scenario:
    V5R2 iSeries with Physical IP address 172.30.0.29 and 172.30.0.37  
and Virtual IP address 172.30.0.45 one one Ethernet line.
    NAS box wanting to use iSeries based RADIUS program to authenticate 
users at IP 172.31.0.104.

So I get an inbound UDP packet delivered to port 1645 on address 
172.30.0.45 from address 172.31.0.104.  The packet is processed by a 
Java program and a respose packet is sent back to 172.31.0.104.  
Unfortunately the source address of the response packet is 172.30.0.29 
so the NAS box ignores it.  I can point the NAS at 172.30.0.37 but same 
result, response packets come from 172.30.0.29.

What must be done to make the source address of the UDP response packet 
be the same as the inbound packet?  Java does not allow us to set the 
source IP for the packet as that probably breaks some RFC I would think.