Re: SNMP over NAT

[Michael S. <ms...@sy...>]

Am 11.03.19 um 14:15 schrieb Kes Smith:
> I have a laptop I often use while outside the house   ie on the WAN side of
> the home modem router.
> I have a raspberry pi on the inside of the house    ie on the LAN side of
> the home modem router.
> The  raspberry pi is running NET-SNMP version 5.7.3.
> I can snmpwalk all the MIBs of the raspberry pi while at home on the LAN,
> but not while outside the house on the WAN.
>
> All port forwarding is set up on the home modem router, and I sucessfully
> use port forwarding with dydns, for a number of services, every day.
>
> The port forwarding on the home modem router for the SNMP service on the
> rasp pi looks  like this
> "home router WAN IP":1234  --> 192.168.1.131 : 161
>
> I have a feeling, but no evidence, perhaps I read it somewhere or someone
> suggested it, that the SNMP stack on the rasp pi is responding snmpwalk
> requests from the WAN side of the home modem router, but can't get it's
> packets back out across the home modem router to the WAN. Perhaps someone
> can comemnt on this.
>
> I have also heard that SNP does not support NAT, but even if this is true I
> know there is a work around for everything, if there is a will.
>
> Can anyone give me ideas for a workaround this problem or any other ideas?
>
>
>
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SNMP works over NAT.

Please check it the IP packets arrive at your RPI. tcpdump is your friend.


Please also note that SNMP works over udp, not tcp. Please check if you
configured the correct NAT on your router.

Mit freundlichen Grüßen,

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