Closing the PPTP Port Under Windows 2000?

phnork asks: "I have asked many skilled Win2K users and networking specialists how to close Port 1723 in my Win2K system. I have searched the net unsuccessfully, browsed news groups, asked my ISP techies, and even asked my wife. But, although all agree the port normally used for PPTP (VPN) should not be open, no one has taken the time to document how nor post the solution where it can be found. In fact, I have found that most security issues that abound in the Wide World of Windows occur because those in the know, do not. Not even Microsoft! If they did, the solution would be as easy and straight forward as setting up a printer. Networks and security are still relegated to the nether worlds of the 80s where we used to have problems with every printer installation and computers were hauled to a grinding stop by the inability of the protocol lords to arrive at a consensus. But, maybe now the solution is at hand. Now that I have asked for help maybe someone will come forward with those super words, 'Try this...'." What other hard-to-close ports have you found open in your Win2k install. What did you have to do to close them?

Comments

RRAS?

[Grizzletooth]

Are you running Routing and Remote Access Services on that machine? I don't see 1723 as a default open port on my servers that don't have RRAS enabled.

hardware firewalls / nat routers

[Feztaa]

Putting your win2k box behind a NAT Router or a hardware firewall of some sort will block connections to that port from the internet. While not an optimal solution, it beats having the port open to the internet! ;)

Try TCPView from sysinternals

[Fat Cow]

That should tell you which process is listening on that port. Then you can stop the appropriate service or kill the appropriate process.

Re:Try TCPView from sysinternals

[Chase]

On Win2k?

Here is what I got when I tried your suggestion.

C:\>netstat -a -o

Displays protocol statistics and current TCP/IP network connections.

NETSTAT [-a] [-e] [-n] [-s] [-p proto] [-r] [interval]

-a Displays all connections and listening ports.
-e Displays Ethernet statistics. This may be combined with the -s
option.
-n Displays addresses and port numbers in numerical form.
-p proto Shows connections for the protocol specified by proto; proto
may be TCP or UDP. If used with the -s option to display
per-protocol statistics, proto may be TCP, UDP, or IP.
-r Displays the routing table.
-s Displays per-protocol statistics. By default, statistics are
shown for TCP, UDP and IP; the -p option may be used to specify
a subset of the default.
interval Redisplays selected statistics, pausing interval seconds
between each display. Press CTRL+C to stop redisplaying
statistics. If omitted, netstat will print the current
configuration information once.

I suggest downloading fport. Its very similar in function to lsof.

Try this...

[skinfitz]

ZoneAlarm

Alternatively you can block any port on a Windows 2000 LAN adapter by enabling TCP/IP Filtering under the TCP/IP properties for that adapter. The way it works is you enable it which will block everything, then you must enable the services you would like to use.

joke.. right?

[undef24]

This is a joke right?

Go download Active Ports and see what program is actually casuing that port to be open.

You can also try running this document in the reverse order to uninstall PPTP :)

Also this...

[boobox]

I use Zone Alarm and also utilize Steve Gibson's Shields Up! to check my ports.

RPC Config

[Vlad_Drak]

By default RPC/135 listens on 0.0.0.0, but you can change this by using MS's rpccfg.exe to listen on the loopback only.

http://www.microsoft.com/windows2000/techinfo/re sk it/tools/new/rpccfg-o.asp

Also, port 445 is open, even if you disable File and Print Sharing. To fix that hole, open up regedit and change:

HKLM\System\CurrentControlSet\Services\NetBT\Par am eters\TransportBindName from '\Device\' to nothing. You can't use the workstation service|CIFS outbound either when you do this though, and you have to reboot for it to take should you want to switch back.

I've never had a problem with PPTP or the port you mentioned, maybe try disabling Routing and Remote Access, or other services.

I have my Win2k3 box only listening on 22, OpenSSHd and scp work like a champ.

Michael Johnson took over the NetworkSimplicity OpenSSH installer, which makes it too easy not to use SSH on Windows.

http://lexa.mckenna.edu/sshwindows/

-Vlad

TCP/IP settings...

[ameoba]

Doesn't the advanced TCP/IP settings under 2K allow you to filter ports?

Alternately, you could write a dummy service that listens on a port, accepts connections & throws all data away, forcing attackers to time-out.

Windows services

[Hard_Code]

windows services

My guess is Routing and Remote Access, which along with the alarming Remote Registry Service, should be one of the things you turn off by default on a new install. No different from turning off all the crap that is installed on a typical default Linux installation.