SNMP Community String ???

[S.Vishwanath]

Hi

I want to know more about SNMP Community Strings.

What are this SNMP Community String, & what do they signify?

What is this "public" used in the field of Community String?

Please also let me know what other values can be used in the Field of Cummunity String other than public. ??

And what does these values like public . . . signify.

Looking forward for info.

Thanks in Advance.

Vishwa.

[Rado1x]

snmp community string is some "password" necessary to read/write snmp data.

I recomend you to change this string to another one. But you have to set up on both - snmp client and snmp server.

[S.Vishwanath]

Hi Rado1x

Thanks for ur kind effort.

But I'm not clear from ur suggessation. I would like to explain my sceniro below :

I do have a application that acts as a server & sends snmp traps to the registered clients.

Inside the application the community string is set to Public.,

Know my customer wants to set the comunity string to some other value other than public & I should provide a facility to the outside world so to accept the customer's desired string. I'm planning to do this via., a Script which accepts the community string from the user & then call the actual Unix Program by passing his desired string as a command line parameter.

Currently we have hard coded by setting the community string to public. And know I want this to be in a mutable format.

That is he might want to change from public to some thing else., & I don't know what else can be used other than public. Like is there any thing like Private & any thing else.

So, I want know to what other values that the commuity string can be set with other than public. Hope it is clear know.

[Neo]

If you look at network devices as clients and devices that received SNMP traps or poll devices as servers then the community string is the same as apassword that the server issues to the client device during a remote query. The string can be just about anything reasonable, as long as the client and the server use the same community strings.

Most network devices allow different levels of SNMP access, for example: READ ONLY or READ/WRITE. Each one of these levels of access would/should have a different (hard to guess) community string.

When a client sends an SNMP trap to a server receiving SNMP trap information, the SNMP community string is not required.

However, some devices use the SNMP community string as a password for terminal (serial and monitor) access to the device as well. Don't just change them and forget them

That is just about it........ the poster stated that the device was only sending traps, so the community string is not so important between client-server (no server queries to the client device) but should be changed for security reasons so something other than the default value, i.e. public.... Make sure you document the change somewhere safe so if you forget to tell the next responsible person after you leave the project, they will have a roadmap of the changes you made!

However, never fear... most SNMP community strings can be reset from the console/monitor of the device (or with physical access to the device). Yet, if you have hundreds of devices..... depending on this technique (physical access to reset) is not a good idea

[zillah]

Thanks Neo

When a client sends an SNMP trap to a server receiving SNMP trap information, the SNMP community string is not required.

My understanding to client and server are this:

1- Managed station (agent or Network element) can be router, switch, hub, printer, ,,,ect has software called server.

2- Network Managemnet Station (NMS) which is normally PC has got software called client.

3- Managed station (agent) send trap to (NMS).

http://www.comptechdoc.org/os/window.../wtcpsnmp.html
Trap - A command or message used by the agent to inform the manager of a certain event.

A- Now can the client (Manager) send trap to server (managed) ?because my understanding to your explianantion that client (Manager) is able to send trap to server (managed),,,,please correct me

B- What is the meaning of public and private ? why have they got these names ?