North American Network Operators Group
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Re: How to secure the Internet in three easy steps

  • From: William Warren
  • Date: Sun Oct 27 21:05:40 2002

actually with the merger of At&t and comcast most cable inet customers will be through them.

Joseph Barnhart wrote:
Not really

On Sun, 27 Oct 2002, Matthew S. Hallacy wrote:



On Sun, Oct 27, 2002 at 02:35:23PM -0500, Eric M. Carroll wrote:
Sean,

At Home's policy was that servers were administratively forbidden. It
ran proactive port scans to detect them (which of course were subject to
firewall ACLs) and actioned them under a complex and changing rule set.
It frequently left enforcement to the local partner depending on
contractual arrangements. It did not block ports. Non-transparent
proxing was used for http - you could opt out if you knew how.
While many DSL providers have taken up filtering port 25, the cable
industry practice is mostly to leave ports alone. I know of one large
Untrue, AT&T filters the following *on* the CPE:

Ports  / Direction / Protocol

137-139 -> any Both UDP
any -> 137-139 Both UDP
137-139 -> any Both TCP
any -> 137-139 Both TCP
any -> 1080 Inbound TCP
any -> 1080 Inbound UDP
68 -> 67    Inbound UDP
67 -> 68    Inbound UDP
any -> 5000 Inbound TCP
any -> 1243 Inbound UDP

And they block port 80 inbound TCP further out in their network. Overall,
cable providers more heavily than cable providers.

I'd say that AT&T represents a fair amount of the people served via cable
internet.



Regards,

Eric Carroll

--
Matthew S. Hallacy                            FUBAR, LART, BOFH Certified
http://www.poptix.net                           GPG public key 0x01938203




-------------------------
Joseph Barnhart
Florida Digital Turnpike
Network Administrator
http://www.fdt.net
http://www.agilitybb.net
-------------------------

--
May God Bless you and everything you touch.

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Isiah 54:17 No weapon that is formed against thee shall prosper; and every tongue that shall rise against thee in judgment thou shalt condemn. This is the heritage of the servants of the LORD, and their righteousness is of me, saith the LORD.