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New Member

SNMP Community String Public

I have configured all switches and routing modules with new community strings. however if i do an snmp walk, the interface vlan addresses come up as public. how do i remove the default community strings from the vlan interfaces

  • Other Network Infrastructure Subjects

Re: SNMP Community String Public

What does not snmpwalk output show?. What type of switches/code is this?

New Member

Re: SNMP Community String Public

Thank you for your reply,

I have used a network monitoring tool called SNMP sweep by Solarwinds. I added the network addresses to cover the VLAN, and the VLAN Interfaces and HSRP address can back as public.

The switch is a 6509 with MSFC. I have configure SNMP Community strings on the switch and MSFC, and removed any public or private comm strings.


Re: SNMP Community String Public

If have a 5500 with RSM or 6509 with msfc then you will have to change them on the layer 3 side also not just on the layer 2 side . for more info we need the switch models and info .

New Member

Re: SNMP Community String Public

The model is a 6509. I have configured snmp at both layer 3 and layer 2. I have used a tool called solarwinds. It picked up the VLAN Interface addresses as cisco default community strings public, which i would like to remove

New Member

Re: SNMP Community String Public

Uh... Let's clear up a few things first:

1. If you're polling using Solarwinds, there are only a few things you can hit:

- The sc0 interface on the switch.

- The defined interfaces on the rtr (incl loop).

So if you're getting a response from Solarwinds indicating that something is responding to SNMP (with a string of public) on the "VLAN" interface - you're talking something defined on the router.

2. Therefore, this whole "layer 2" and "layer 3" thing is kind of a red herring. Let's talk router.

3. Just configuring a "new" SNMP string with the appropriate command, like this:

snmp-server community IBMRAWKS ro

or whatever only ADDS to the strings already defined. It doesn't REPLACE what already exists. You must clear the previous SNMP string using the "no" command - standard IOS. Like this:

no snmp-server community public ro

And BTW: From one IBM'er to another, ITCS guidelines dictate that you're supposed to secure the equipment from screens using an ACL. Like this:

snmp-server community LOUANDSAM ro 10


access-list 10 permit

access-list 10 permit


4. You should also screen your switches using IP Permit lists (I do for both SNMP and telnet). [Easy to do on Cat 5000 and Cat 6000's using CatOS.]

5. Don't forget to save your config.

6. I've been working on a "hardened" IOS for both internal and external routers, switches, etc. Since you're doing Solarwinds sweeps, perhaps we can touch base and exchange information? If you have a Sametime id - can you drop a note with it? Be nice to share information.