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AT&T/SBC will block the following ports as a default for members using a Dynamic IP package.

Outbound - TCP port 25
Inbound and outbound - TCP ports 135, 139, 445 and 1025

The port 25 block can be removed but it is suggested that you you do not do this unless absolutely necessary.

To request removal of the filter, use the Abuse of Service form at »help.sbcglobal.net/servabuse.php to contact our Abuse team and choose the "Opt-Out Port 25" under Abuse Type. Enter your account Member ID (also called your SBCIS PPPOE Login ID or User ID) to opt-out. If you have multiple SBCIS accounts you want to opt-out, please submit a separate form for each Member ID. Do not enter your email addresses from the other mail hosting provider. You should expect that it will take SBCIS 12-24 hours to process your request.

After receiving a confirmation email, sent to the SBCIS Member account ID being opted-out, you will need to logoff the SBCIS network and turn off your DSL router or modem for 1 minute to remove the filter. You should then turn your modem and system back on and log in using the normal procedure.

The SMTP Port 25 filter does not affect Members using Web mail to any mail provider, VPN connections to a private company or university mail server, dedicated (e.g. T1/T3 or Frame-Relay) or "static" IP addresses.

In response to a recently announced vulnerability attributed to computers running certain Microsoft Operating Systems, SBC Internet Services has blocked TCP ports 135, 139, 445 and 1025 for all basic dynamic subscribers nation wide. (These ports are no longer being blocked for static subscribers.) These ports are known to be used by worms and viruses to spread to other computers through the Internet. Blocking these ports may affect your ability to use:

* Microsoft Outlook to access a Microsoft Exchange server over the Internet
* File sharing over the Internet
* Print sharing over the Internet

This action should not affect the vast majority of our members, and does not affect using Microsoft Outlook or other email programs over a local area network.

The block is scheduled to begin on Thursday, April 29, 2004. Beginning at that time, you may notice that you are unable to continue the above activities over the Internet. Other uses of your Internet Access service will not be affected.

How long will this port blocking last?

With the cooperation of subscribers, and the use of anti-virus software and firewalls, we hope to have this issue contained in a relatively short period of time.

Are there any workarounds?

You may be able to work around port blocking. Some workarounds you may want to investigate include:

* Using Microsoft Outlook Web Access
* Using Microsoft point-to-point tunneling
* Using a Virtual Private Network (VPN)

You may need assistance from a networking professional to set up these workarounds.

Will anything else be affected?

Other computer applications may use ports 135, 139, 445 and 1025, although they are mostly used for the purposes outlined above.

Why are you doing this now?

As the result of a growing number of apparent security vulnerabilities, SBC Internet Services is blocking ports in an effort to protect our networks and the security of our customers computers.

Because SBC Internet Services conducts security checks on its network, do members need to be concerned about additional Internet Security measures?

Yes, members should realize they are responsible for the security of their own computers. Our network security scans and port blocking are not a substitute for protecting and patching your own computers. We recommend use of personal hardware and/or software firewalls, and we suggest that all members install anti-virus software to scan the contents of their computers for viruses and worms.

Feedback received on this FAQ entry:
  • The port 25 block optout instructions no longer work (form was changed, doesn't have the correct entry anymore)

    2009-05-22 14:09:14 (devicenull See Profile)

Expand got feedback?

by meskinct See Profile