Loopback address and web browsers [Info][Closed]

Can anyone tell me why a loop back address is needed for a web browser. I could no find any exploits using the loop back and I am not sure if it is possible to exploit. I fact I think it is safe. I had been allowing all traffic to 127.0.0.1 but decided I did not need it. I decided to block it as the only reason i could think of you might need it was for web dev. tools i.e. front page

I was just wondering if someone might have some info I was unaware of. :THNK

OD

Edit note: So far no ill effects

Mozilla communicates with itself via loopback at startup. Bro0wsers also communicate with virus scanners and spyware scanners via loopback. Don’t know what else. Loopback is how programs communicate within a machine using TCP/IP.

I think if I remember correctly it is something to do with loading pages from the internet if they have not changed it loads them from the files already stored on your computer.
Dennis
EDIT Also it should be UDP blocking it only forces the browser to download all the page from the internet.
EDIT 2 Thinking again UDP should be covered by the rule in Network Zones ;D

Both make sense to me. I knew this was how a machine communicated with itself via tcp. I did not think of web caching, DNS Caching nor AV & AS. Sounds like it might be a good idea to leave loopback open. I knew there was a reason I left it alone before just was not sure exactly why

Any one know of any vulnerabilities using Loopback

Thanks
OD

Any traffic that a computer program sends on the loopback network is addressed to the same computer …
Vulnerabilities ? Yeah, you could always tell someone that they should block 127.0.0.1 (and 0.0.0.0) with
their firewall … or you could have them ping-flood themselves …

The only vulnerability I can think of if you can call it that, is if you use a proxy for your browser to access the internet.
If you block a app. access to the internet it sometimes tries to access through the proxy.
I place a block rule 127.0.0.1 (+ proxy port) to stop this.
Dennis

Thank you all

I knew what Loopback was and how to use it for testing, I was just not sure exactly how the programs were using it.

Thanks to the replies to this post, and the research the replies led me to, I now think I understand to my satisfaction

I’ll leave this open for a little while and close it in about a week

OD