Firewalls and Proxy Servers with PC Access® for Windows

Quick Contents

• Introduction
• Solution
• Known Firewalls and Proxy Servers
  • Microsoft ISA Server
  • Deerfield.com Wingate Proxy
  • Microsoft Proxy 2.0
  • Ositis WinProxy 2.1
  • Zone Alarm and Zone Alarm Pro
  • Sygate Personal Firewall
  • Windows XP Internet Connection Firewall

Introduction

PC Access for Windows is an enhanced emulation program that allows you to remotely access the MLS system. If your MLS office provides Internet access to the MLS system, you should set up PC Access to connect using TCP-Telnet. For more information, see: Connection Method group.

Many local area networks (LANs) and end-users may use a firewall or proxy server on their Internet connection. You may use a firewall or proxy server to prevent hackers from accessing your system. The firewall or proxy server may also prevent you from using the TCP-Telnet connection method in PC Access for Windows to connections to your MLS system.

PC Access TCP-Telnet connections rely on the Windows 16-bit TCP/IP-Winsock driver (C:\WINDOWS\WINSOCK.DLL) for its Telnet sessions. Windows TCP/IP-Winsock Telnet sessions use Port 23 or Port 24. If the firewall or proxy server does one or more of the following:

• blocks ports 23 or 24
• does not properly route the Windows 16-bit TCP/IP-Winsock calls
• logs into the firewall or proxy server before allowing telnet access to the Internet

Solution

• your firewall or proxy server correctly routes the Windows 16-bit TCP/IP-Winsock calls through the firewall or proxy server's SOCKS driver.
• your firewall or proxy server allows inbound and outbound traffic through the Telnet ports 23 or 24
• you provide direct telnet connections through the firewall or proxy server where the PC Access TCP-Telnet sessions will connect to the MLS system via the Internet.

• Note: MFM Technical Support does not support or provide assistance with configuring any firewall or proxy servers. If you are unsure about how to configure or work with your firewall or proxy server, contact technical support for your firewall or proxy server software.

Known Firewalls and Proxy Servers

• Note: MFM Technical Support does not support or provide assistance with configuring any firewall or proxy servers. If you are unsure about how to configure or work with your firewall or proxy server, contact technical support for your firewall or proxy server software.

Microsoft ISA Server

• MSKB: 16-bit Winsock Applications Are Supported Only on Windows 2000 and Windows NT 4.0 with ISA Server Firewall Client
  http://support.microsoft.com/default.aspx?scid=KB;EN-US;Q305620&

Deerfield.com Wingate Proxy

• http://www.deerfield.com/
• Note: some Wingate versions do not allow direct Windows 16-bit Telnet connections.

Microsoft Proxy 2.0

• Note: to our knowledge, Microsoft Proxy 1.0 works with PC Access for Windows TCP-Telnet sessions.

Ositis WinProxy 2.1

On the Ositis Web site, you will find a solution posted in their Knowledge Base on how to configure WinProxy 2.1 for direct Telnet connections. Here is the hyperlink to their Knowledge Base article:

• Reference 990301-000020

Based on information on the Ositis Web site, WinProxy 3.0 does not have this limitation. You also do not need to configure WinProxy 3.0 to allow direct Telnet connections through the proxy server.

Zone Alarm and Zone Alarm Pro

Sygate Personal Firewall

The PC Access for Windows TCP-Telnet session will show a 609 error when a firewall or proxy server blocks access to the Telnet ports in the Windows TCP/IP-Winsock driver. The Windows TCP/IP-Winsock Telnet ports are either 23 or 24.

To connect to the MLS system via the Internet and PC Access for Windows, you will need to do one of the following:

• configure the Sygate Personal Firewall to allow Telnet sessions (if this option is available).
• temporary disable Sygate Personal Firewall.

Windows XP Internet Connection Firewall

However, if you use a third-party firewall or proxy server program and/or use an ICMP checking program to keep your connection alive with the Windows XP Internet Connection Firewall enabled, you will probably experience Internet connection problems due to a high volume of packet loss.

If the packet loss problem relates directly to the Windows XP Internet Connection Firewall, you will need to do the following in Windows XP to eliminate the packet loss:

1. In Windows XP click Start | Control Panel | Network Connections.
2. In the Network Connections window right-click on the Local Area Connection icon and click Properties.
3. In the Local Area Connection Properties window click on the Advanced tab. Select Protect my computer and network by limiting or preventing access to this computer from the Internet to enable Windows XP firewall.
4. Click the Settings button (towards the bottom of the window) to open the Advanced Settings window. Click on the ICMP tab and select Allow incoming echo request.
5. Click OK | OK to return to the Network Connections window and close it.

Microsoft Knowledge Base References:

• HOW TO: How to Enable the Internet Connection Firewall Feature in Windows XP
  http://support.microsoft.com/support/kb/articles/Q283/6/73.ASP
• How to Manually Open Ports in Internet Connection Firewall in Windows XP
  http://support.microsoft.com/support/kb/articles/Q308/1/27.ASP
• Programs Require Manual Port Configurations with Internet Connection Firewall
  http://support.microsoft.com/support/kb/articles/Q307/5/54.ASP
• Unable to Connect Error Message Using MIRC and ICS
  http://support.microsoft.com/support/kb/articles/Q227/1/48.ASP
• HOW TO: Configure a Connection to the Internet in Windows XP Professional
  http://support.microsoft.com/support/kb/articles/Q305/5/49.ASP

Last modification date: Friday, March 21, 2003 11:47:30