Dear My reader ,


I have here something which is confusing me .


The Goal which I want to Implement it is :-


1-       Disable Internet – Completely – On All Users inside my Network, which they are using Internet through My ISA Server 2004  Std edition.



How our Infrastructure is :-


We have 1 ISA Server Std Edition 2003, SP2 ISA
ISA Server Configured with 2 NIC as External & Internal .
The External is Connected to HW Firewall device like CISCO PIX Firewall.
The External is Connected to My Internal LAN.
We have Our mail server hosted on Our ISP Side and we are using POP3 & SMTP  [ POP3 Account with MS-OUTLOOK 2003 ].
I have here 60 users are configured as [  SNAT / Web Proxy Client / Firewall Client ] .

My ISA Server configuration Firewall Policy as following :-


1-Puplish mail server rule for MY Server on ISP for SMTP Protocol .

2-Puplish mail server rule for My Server on  ISP for POP Protocol .

3-Access Rule for Internet .


To implement my goal, I did as following :-


I disable my Only access rule which is called OPEN Internet .

I left My Publish server role without touching it.


I found that , all the users are able to send , but unable to receive and using POP3 at all. And they are unable to browse internet .


So , why they are unable to use POP3 while they are able to use SMTP ?


But if I disable the Puplish server role, and I change the access rule Protocol from ALL OUTBOUND Traffic to Selected Protocols “ SMTP / POP3 “  , I found that they are able to use SMTP / POP3 but unable to browse internet .


My question is , why this Happen ?
Who is Participating?
Rich RumbleConnect With a Mentor Security SamuraiCommented:
Pop3 uses port 110 for sending and port 25 for SMTP sending. What you should do is allow the IP of the pop3 and smtp. Your rule should be something like:
Allow any port to port 25 (for sending)
Allow any port to port 110 (for sending) is the subnet your users are on, and is the smtp/pop3 server ip
For recieving you should allow:
allow any port to any port    again, is the pop3 and or smtp server and the is the private subnet.
It's called egress and ingress filtering. http://en.wikipedia.org/wiki/Egress_filtering http://en.wikipedia.org/wiki/Ingress_filtering
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