[Netdisco] discover_only and discover_no options

[Martin K. <ko...@fu...>]

Hi everyone,

I wonder how discover_only and discover_no options really work. With
these options configured like this:

#discover_no    =
discover_only  = 10.239.0.0/16

I can still see traffic to other network(s) than the one specified in
discover_only. Captured with tshark it is as follows:

>   0.000000 10.238.250.84 -> 10.230.143.238 SNMP get-request 1.3.6.1.2.1.1.7.0
>   1.001438 10.238.250.84 -> 10.230.143.238 SNMP get-request 1.3.6.1.2.1.1.7.0
>   2.005407 10.238.250.84 -> 10.230.143.238 SNMP get-request 1.3.6.1.2.1.1.7.0
>   3.009412 10.238.250.84 -> 10.230.143.238 SNMP get-request 1.3.6.1.2.1.1.7.0
>   4.013409 10.238.250.84 -> 10.230.143.238 SNMP get-request 1.3.6.1.2.1.1.7.0
>   5.017396 10.238.250.84 -> 10.230.143.238 SNMP get-request 1.3.6.1.2.1.1.7.0
> 101.505854 10.238.250.84 -> 10.230.142.234 SNMP get-request 1.3.6.1.2.1.1.7.0
> 102.509404 10.238.250.84 -> 10.230.142.234 SNMP get-request 1.3.6.1.2.1.1.7.0
> ...
> 1501.155385 10.238.250.84 -> 10.230.172.234 SNMP get-request 1.3.6.1.2.1.1.7.0
> 1502.157920 10.238.250.84 -> 10.230.172.234 SNMP get-request 1.3.6.1.2.1.1.7.0
> 1503.165434 10.238.250.84 -> 10.230.172.234 SNMP get-request 1.3.6.1.2.1.1.7.0
> 1504.169908 10.238.250.84 -> 10.230.172.234 SNMP get-request 1.3.6.1.2.1.1.7.0
> 1505.173926 10.238.250.84 -> 10.230.172.234 SNMP get-request 1.3.6.1.2.1.1.7.0
> 1506.177437 10.238.250.84 -> 10.230.172.234 SNMP get-request 1.3.6.1.2.1.1.7.0

Have I missed something or is this behavior correct? Is there a way to
prevent any Netdisco communication to certain networks other than using
e.g. IPtables?

Thank you for any help,

Martin