[AGENT++] Changing the source IP (agent-addr) of the Traps. (Newbie)

[Jochen Katz]

Hi,

> I notice that the trap I've set up has agent-addr set as the localhost
> Ip (127.0.0.1).
> I'd like to change that to the proper IP, also because my device has
> multiple interfaces.

as the mib entries for a v1 trap don't allow to set the agent address, 
it is not set in the pdu by agent++. snmp++ then tries to set it to the 
IP for the host name returned by gethostname() function. Obviously this 
name resolves to 127.0.0.1.

As a short term solution, you can patch the 
NotificationOriginator::send_notify() function to call 
pdu.set_v1_trap_address() right below the line "if (mpModel == mpV1) {".

I can think of two possible enhancements:
1) provide a static conversion table that maps IP ranges to agent 
addresses to NotifiactionOriginator. This could look like
    192.168.0.0/16 --> 192.168.0.1
    10.0.0.0/24 --> 10.0.0.254
    10.0.1.0/24 --> 10.0.1.1
    0.0.0.0/0 --> 10.4.4.4 (default)

2) Add some code that tries to find out with which source IP the trap 
will be sent and use this IP as agent address.

Regards,
   Jochen