How to Allow Internet Access on ISA Server Machine.

Many people complain of not being able to obtain access to the Internet from the ISA Server computer itself. This tutorial will show you an easy way to solve this common problem.

1. First, you must decide which protocols you need access to on the external network. Below is a table of the most popular ones:

Protocol Description Port Protocol Direction
HTTP Hyper Text Transfer Protocol 80 TCP Outbound
HTTPS Secure Hyper Text Transfer Protocol 443 TCP Outbound
Gopher Gopher protocol 70 TCP Outbound
FTP FTP Protocol 21 TCP Outbound
POP3 Post Office Protocol v.3 110 TCP Outbound
POP3S Secure Post Office Protocol v.3 995 TCP Outbound
SMTP Simple Mail Transfer Protocol 25 TCP Outbound
SMTPS Secure Simple Mail Transfer Protocol 465 TCP Outbound
NNTP Network News Transfer Protocol 119 TCP Outbound
NNTPS Secure Network News Transfer Protocol 563 TCP Outbound

Now, you will create an IP Packer Filter for each protocol that you will use on ISA Server machine.

2. Open the ISA Server Management console, navigate to [Server] expand Servers and Arrays, then expand [SERVER] and go to IP Packet Filters. Here you’ll create the IP Packet Filters to allow access to the Internet from ISA Server Machine itself. I will go over an example for SMTP. On the General tab you can enter a meaningful name for the filter and an optional description.

  1. On the Filter Type tab, with help from the table, set up the IP Packet Filter settings.


  1. At Local Computer, select the option Default IP address(es) on the external interface(es). If necessary, you can specify an IP Address of ISA Server
    computer that will be used to allow access if you have multiple IP addresses on the external interface of the ISA Server computer.


  1. At Remote Computer select the option All remote computers. If necessary, you can specify a single computer or a range of computers.

With this example and the table above you can create the filters necessary to allow the access to SMTP, POP3(S), IMAP, HTTP(S), SMTP(S), NNTP(S) and among others.


To to the Policy Elements and then the Protocol Definitions node. You will find the definitions of the protocols. Always remember to invert of Inbound for Outbound.

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Author: Alexandre Cavalcante Alencar
Technical Support and Coordenator
Email: [email protected]
Phone: +55 (85) 296-9876
Mobile: +55 (85) 9995-3302
Microsoft Official Curriculum (Windows 2000) MCP and MCSE coming soon:
Aspec – Assessoria, Processamento e Contabilidade S/C Ltda
Microsoft Certified Partner and Microsoft Certified Solution Provider
Email: [email protected]
Phone: +55 (85) 254-3223                              
Fax: +55 (85) 254-4779

Alexandre Cavalcante Alencar is a technical support and coordinator of Aspec, develop, support, consulting, account firm located in Fortaleza, CE Brazil specializing in account software. Current project is to develop a practical how to manual for the ISA Server and Windows 2000 OS Server/Professional.

About The Author

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