Confusion regarding network appliances

rht

Hi guys i am studying for network+ but i am confused regarding the difference between each of the following network appliances:

1.Content filters
2.Content switches (what layer do they work at 2,3 or 7)?
3.Proxy filters

Thanks

Plantwiz

Welcome,

What tools do you have to assist you in your studies? Have you worked with any of the above on a live network? Asking because if you have some experience to pull from, you will understand the answers provided a bit better. Additionally, I (and others) can give you examples of some of these devices as used in a live environment.

Ex. Barracuda has a device that works as a content filter (i.e. 'information filter') however, IIRC they also have a device that can handle two or three of your points. Been a while since I've used Barracuda, but we had a few clients interested in their stuff when they first got going and eventually we/they changed out of that product line into other options. So, what types of things are you familiar with?

rht

actually i have no experience in IT yet but i am hoping this will change soon...anyway i am familiar with client side and server proxies, i also read about security network appliances that combine stuff like antivirus, spyware, anti phishing, spam and also provide URL filtering. So my question is how do all the above fit together? are they hardware or software or terms that describe both? i am confused really :P

excuse my English, i hope i am making sense

Plantwiz

I would recommend you pickup Mike Meyers Text and/or the Sybex text on the subject.

Download a copy of the objectives and work through those topics so that you gain an understanding.

And of course, if you are still stuck, post your questions here (like you just did).


Keep in mind, the OSI model is a theory. And for the most part one can/should be able to trace their way through the OSI model on their particular network (or on the network they are working on). That said, many parts are moving and today, several appliances may work at one or more levels which can lend to some confusion.

In essence, switches work at layer 2. However, Content switches work at higher levels of the OSI model. Routers work at Layer 3, or more correctly, a layer 3 'switch' differs from a true router, but visually, one will not see a difference per se. The difference lies on the inside and how the device is built to handle the traffic. A layer 3 switch utilizes software logic and the hardware to improve performance. Layer 3 switch does not typically use WAN ports, mostly found on intranets.

A content switch uses layer 4 to 7. These switches look for sessions to transmit data between rather than individual packets as a lower layer switch would use.

When shopping for specific devices, I'd recommend reading the documents from the manufacturer about where the appliance falls and what it services. Some will span a couple layers and in actuality, some layers of the OSI are 'skipped' because the device manages the traffic simultaneously (or so it will appear).

This is a fun page with some helpful graphics
Programmer Help: ISO-OSI Layer Model + TCP/IP Model

About mid-way in the page is another image with some examples of where the devices sit:
SOA Magazine - Issue XXXVIII - XML Appliances for Service-Oriented Architectures
RMON2


A quick summary article on OSI
Foundations: What Are OSI Layers? | WatchGuard


After all this, keep in mind, for Net+ the material will be wanting you to have a 'general understanding' not necessarily master everything just yet. Get your hands on a lab or virtual lab to work through some of the material. You will want to understand it more fully if you intent to pursue a career in IT and IT security.
Hope that helps some.

PW

chipcreep

I just started studying for Net+. Plantwiz, those links were helpful.

rht

Hey thanks for the links they are excellent. My confusion cleared up after reading the Advanced network devices chapter in Mike Meyers Network+ book.