N00b Question

[Harshal Dedhia <harshal.dedhia () skybird-travel com>]

Hi,
I am very new to the firewall and network security world. I have a 
situation wherein  I need to block webbased email access and the ability 
to upload attachments to web-based email. I also need to ensure that 
MSN/yahoo chat is disabled and quotas are established for web surfing.

Is there an Open Source solution to this problem. The network comprises 
Cisco Routers and 500 series firewalls.

Cheers!
Harshal