SNMP Overview

10 minutes
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Alright, here we go again. I said MP overview. Alright. SNMP enabled network devices share information about itself and its activities. They complete system. SNMP system consists of what a manager and an agent.

Okay? Imagine an agent or a management system that uses SNMP it polls and receives data from any number of network devices. SNMP takes information from anybody out there, okay. SNMP agent processor that runs the network device being monitored, all types of data are gathered by the device itself. You can read it yourself, okay? So you have a manner you have a manager and you have an agent SNMP I don't this is not a big deal.

You're gonna be using it and a third party application anyway in the real world. But know that you do have a manager and an agent. Keep that in mind. It asks you any questions here. They will SNMP has a management information base your MIB not men and black, but the management information base. He switches automatically collects data about itself, its resources and its interface the information is stored in the MIB when you purchase your switches or your routers, all right, make sure you have the up to date MIB.

Why is that because you have something called users or user object identifier for users whatever remember Object Identifier or the identifiers or all ID, object identifiers. Well, that is everything in your, in your in your switch everything in your router. Everything you see every line you see there has an number that's attached to it, which is in your MIB. The syslog messages that pop up I everything that you see on that screen has an ID, and ID is a screwed up number. It looks like a screwed up IP address. Okay, is it 10 dot 911 dot 125 dot one?

Yeah. It's you don't need to remember IDs. So don't worry about it. Okay. But that's how everything is organized in all IDs when you're getting this information. That's where you're gonna look at all right.

And it's based on a tree. So when you go into your MIB, right, because you set up a community string and all that good stuff, and you start, you know, expanding that tree because you're looking at certain things, and they get the information that you're looking for. And there they are doing things manually through, you know, godforsaken old equipment, but we don't use old equipment, do it, we use third party applications. And I keep saying that, because there's a reality. Okay, looking at the MIB data. SNMP manager must send SNMP poll or query to switch and the port number that you need to look at is 161.

That's the SNMP agent using UDP 161. Repeating that for a reason SNMP agent using UDP 161, when the SNMP manager sends SNMP poll or query to the switch, because the switch as the agent, right, the SNMP server or manager will send that to the switch via that UDP port. Okay. Now the commands obviously, it's gonna be something that you download, you can type it if you're not see ally or what have you get requests, get next request, get bulk requests or set requests. Again, the value GET request is just a value one particular ID All right, and then maybe get next request. Obviously, again, the next request that you're that's in line, get bulk, you're getting a whole bunch of information at once.

And then you saw the request, a specific MIB variable needs to be set to that value. Okay, so you said The request that you want to get so these commands Okay, no Nolan just northern. I mean they're pretty much self explanatory. Maybe not this one, you know set request and specific MIB variable, but you don't get bulk Come on, you're getting more than one information, get the next request after you know, so it's pretty much self explanatory. Okay. Now, this is why I stressed the 161.

Member the manager polls Aquarius and says the information to the switch. The agent is listening for that and UDP port 161 SNMP agents can send on solicited alerts to notify the SNMP manager or real time events at any time. It's done over UDP port 162. What do you need to remember about that? What do you need to remember on solicited alerts? All right coming from agents to the manager using UDP port 162.

That sounds like a question to me. Okay. I will put it in. Okay. So who uses port once that UDP once I see one or 162 unsolicited? Or is it the one that's being pulled a query?

You know, how are they want to phrase it, but pay attention to that. You can use SNMP traps the way news of any event is sent without any acknowledgement that the trap has been received or inform request. It replaces a particular command news of an American sent to SNMP manager and the manager is required to acknowledge the receipt by echoing the request back to the agent. This is an actual command. It's an actual command. Now we are different versions of SNMP.

Nobody uses SNMP version one anymore. That is old school security issues. Do To committee strings, read write our O's, our Ws write SNMP version to see, there's a 32 bit, there's a 64 bit counter, but it doesn't address the security issue, you still have the read only, or the rewrite. Okay? You can have more requests that something that was implemented in there, bulk requests are also part of this particular update. But again, it doesn't look into the security issues.

Now, with SNMP, v3, that guy is looking at authentication, user groups, you can put groups into different levels. So it really does an awesome job and securing your SNMP information because not everybody can just run it, you have to be you have to be authenticated to a particular group. And depending on the group that you're in, you're in a certain level, so you only do or look at certain things. So SNMP version three is the way to go. Obviously, this is the most basic One that everybody uses, but this is the way to go SNMP version three, because that has the security, the urinate goes by Guy, you're shoving everybody into user groups. And those groups are setting to different levels of types of security or where you can look at so definitely, this is what you want to do SNMP version one nobody uses and they do the work for them.

Alright, naming scheme you or enlighten them. Okay? group name, no authentication, no privilege, as I mean packets are neither authenticated or encrypted. So we definitely don't want that right. The groups that were resetting, authentication, no privileged. SNMP packets are authenticated, but are not encrypted.

And then authentication and privilege. SNMP packets are authenticated and encrypted. Definitely you won't be part of that particular group name, right? Because they're the ones that are completely secure. Right? So it all depends Again, here we're doing a comparison of SNMP versions of SNMP.

Version one, you see the SNMP, version one and v2, they both use community string. So there's no real security. Somebody figures out the security goes here that can be read and write read only. Now, you should always put read only before rewrite, people can then actually write and change things. You don't want to do that. So you'll be very careful.

At least you do have a different here. All right, the features of it were version one is a 32 bit within a 64. And this also has bulk requests an informed request messages as well. Okay, so this is why this becomes a little bit more popular, but again, it doesn't address security issues. SNMP version three. Now, the other indication user name, and look at the type of data protection.

We're talking about MD five shop ds 3ds as 120 Oh, five to 256 bit encryption. So we do have security when it comes to SNMP version three, because it's adding authentication and data integrity plus encryption. So you choose, which is better, right? You want to use the latest and greatest anyway. So SNMP version three, no, the different versions. No, the different versions.

No, who uses a community string and who really has a security? Okay, that is what you need to know. No other group man, there's only three of them. There's only three of them. I mean, and they speak just look at this. You know what to say there's no oh my god.

There's no authentication here. And there's no encryption. Here. There's authentication, but there's no encryption, or here we have authentication and encryption. So easy to understand. So these are the tables that you really need to look at.

Need to understand and the nope the ports ports. UDP port 161 is what that's the one that's being is is getting the information from the manager that's polling or querying the devices for UDP 62. It's sending the manager information. Okay, unsolicited. That's the key word on solicited messages. So these are little things I'm telling you to look at.

They're going to be very important. Of course, you do need an agent and you need a manager in order for SNMP more. Okay, that's SNMP to the next

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