Can we block sites from firewall

Dir Sir’s

I have one question:

Is there is some way to *block web sites or block some files
like .mp3 from downloading
, by using firewall.

If there is please give me code for this

I try this
ip firewall filter
add action=reject chain=forward comment=“” content=.mp3 disabled=no reject-with=icmp-network-unr
But it did not work.

Thanks

Eng. Amgad

To block mp3 files, enable and set up transparent web-proxy and add rule to disable mp3

http://wiki.mikrotik.com/wiki/How_to_Block_Websites_%26_Stop_Downloading_Using_Proxy