Knowing Firewalls

[TechFreak]

well,

 

this is my second year in Information Technology Engineering... and in our college we do have internet

services provided to us via WIFI. But we can only use certain websites. on the college Wifi.

 

for eg:

 

We cannot access Social networking sites like Facebook on college's wifi..

 

this is because firewall.. i guess. its restricting certain sites. So now i wanna know that how this all works? How this firewalls restrict certain domains

and also very curious to know that is there any way to use the restricted services?

 

PS This question is only for educational purpose and asked for just feeding my curiousty. so please lead me...

 

thanks

regards

[insane_alien]

its not going to be a firewall restricting site, it will be web filtering software.

 

this can work in a variety of ways, most likely it has a blacklist of domains to be blocked and it intercepts all the traffic and stops the stuff that is on the list.

 

it can also have word filters where it scans sites to see if they contain inappropriate content(this often leads to problems in an academic environment though, it can read "sextant" as 'adult content' and so on.)

 

There are probably more advanced heuristics though.

 

We won't tell you how to bypass this as that is breaking the rules of the network which you very likely signed up to at some point and you could get in a lot of trouble for circumventing them especially if it is to download illegal content.

 

remember, it's not your network so don't abuse it.

[NetSplitter]

Insane pretty much summed this up fairly well. Firewalls themselves do not block "websites". Normally you will see a firewall at the edge of the network allowing/blocking traffic through ACL's and NATing.

 

 

Check out: Websense/Esoft webfilter

 

 

Note though that some firewalls have modular features that allow them to filter websites normally by categories, some might refer to this as a "application firewall". For example (Untangled and ISA).

 

Edited November 21, 2011 by NetSplitter