IP replacement of forwarded v2c traps

Hello List,

Doing some tests with forwarding snmp traps from an intermediate node 
to a receiver node, the SNMPv2c traps that enter get their source 
address replaced by the intermediate node's IP address instead of the 
originators address. Snmpv1 traps are forwarded with the OK (unchanged) 
source address.

What would be necessary to forward the original  source address?

The configuration is:

The intermediate node has net-snmp-5.3.0.1-25.15 on Suse Linux 10 with 
2 networkcards, 1 of them giving access to the 192.168.128.n network 
(own IP 192.168.128.119)  and the other to the 10.236.n.n (own IP  
10.236.1.72) network.

the snmptrapd.conf on this machine contains:

traphandle default /usr/local/bin/trap.log.sh
authCommunity net,execute netbackup_trap
forward default 10.236.4.179

From node netbackup (IP 192.168.128.100) the snmptrap command is:

snmptrap -v 2c -c netbackup_trap 192.168.128.119 .
1.3.6.1.4.1.1211.1.15 "" 0 1 0 .1.3.6.1.4.1.1211.1.15.3.2 s 516serialno

the snmpv2c traps that come in on node 192.168.128.119 have the 
following format when printed by trap.log.sh (all variables):

netbackup
UDP: [192.168.128.100]:32770
.1.3.6.1.2.1.1.3.0 0:0:00:00.00
.1.3.6.1.6.3.1.1.4.1.0 .1.3.6.1.4.1.1211.1.15
.1.3.6.1.4.1.1211.1.15.3.2 "516serialno"

on node 10.236.4.179 (where the forwarded traps go to) we receive:

intermediatenodename
10.236.1.72
DISMAN-EVENT-MIB::sysUpTimeInstance 0:0:00:00.00
SNMPv2-MIB::snmpTrapOID.0 SNMPv2-SMI::enterprises.1211.1.15
SNMPv2-SMI::enterprises.1211.1.15.3.2 "516serialno"


Whereas snmpv1 traps give the following output on the intermediate 
node (192.168.128.119/10.236.1.72):

netbackup
UDP: [192.168.128.100]:32770
.1.3.6.1.2.1.1.3.0 0:0:00:00.00
.1.3.6.1.6.3.1.1.4.1.0 .1.3.6.1.6.3.1.1.5.1
.1.3.6.1.4.1.1211.1.15.3.2 "516serialno"
.1.3.6.1.6.3.18.1.3.0 192.168.128.100
.1.3.6.1.6.3.18.1.4.0 "netbackup_trap"
.1.3.6.1.6.3.1.1.4.3.0 .1.3.6.1.4.1.1211.1.15

And on the destination node (10.236.4.179)

10.236.1.72
DISMAN-EVENT-MIB::sysUpTimeInstance 0:0:00:00.00
SNMPv2-MIB::snmpTrapOID.0 SNMPv2-MIB::coldStart
SNMPv2-SMI::enterprises.1211.1.15.3.2 "516serialno"
SNMP-COMMUNITY-MIB::snmpTrapAddress.0 192.168.128.100
SNMP-COMMUNITY-MIB::snmpTrapCommunity.0 "netbackup_trap"
SNMPv2-MIB::snmpTrapEnterprise.0 SNMPv2-SMI::enterprises.1211.1.15



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