New Member
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3 Messages
dpc3939b automatically opens torrent ports
which is kind of useful...but also kind of scary.
I want to allow Skype, have configured for remote desktop, but want to block torrents.
On the menu go to Advanced, Port Forwarding, there we see all of the automatically opened ports. Next to each entry is a check box, and Edit button, and an X. Uncheck the box, go to some other screen, come back, the box is checked. Delete the entry, go to some other screen, the entry is back. Create my own entry, uncheck the box, go to some other screen, come back, the box is unchecked.
1) Why is the DPC 3939B automatically opening ports? Can this be disabled?
2) How do I disable or delete ports that are automatically opened?
Accepted Solution
VBSSP-RICH
Advocate
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1.4K Messages
10 years ago
Hello megaabite and welcome,
Just to springboard off Comcast_John's post, Comcast only blocks these ports intentionally for networking and customer specific security reasons. However, all Comcast Gateways (CG) contain internal GUI FireWall control facilities that allow you to enable full firewall ports blocking especially for StaticIP devices. Then there is a special GUI True Static IP Port Management facility where you can maximize security on that device and ONLY open prescribed application required ports.
The DPC3939B firmware version can be found within GUI interface Software facility. It is my understanding that the DPC3939B GUI supports auto-control of the Xbox, Skype, uTorrent GUI entities. The reason for this is that customer's can connect whatever devices to the CG and then manually or auto-open any prescribed device ports as follows:
1. ) Xbox - " Xbox Live service uses UDP ports 88 and 3074 as well as TCP port3074, XBOX 360 and computer with AVG Firewall, please ...protocol TCP; direction In; local ports 3390; remote ports 1000-1300, etc."
2.) " Skype requires unrestricted outgoing TCP access to: All destination ports above 1024 (recommended). or. Ports 80 and 443, etc. "
3.) For uTorrent " It is generally recommended to not use any port in the range 6881-6889 or ports under 1025. Any other port except for 25 or 110 is acceptable."
Lastly, whenever you make any vital manual CG supported setting change, it is always good practice to insure permanent implementation by resetting the CGs and checking that it stuck on a permenant basis, like most industry standard modems.
Hope this helps you out.
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Accepted Solution
megaabite
New Member
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3 Messages
10 years ago
got an idea. tried and experiment.
started a BitTorrent download on one of the computers. went to the Port Forwarding page. there were two new entries for BitTorrent for that computer. could not be disabled or deleted.
stopped the torrent download. entries could not be disabled or deleted (withtou returning from the dead).
closed BitTorrent. now the entries can be disabled or deleted.
tried another experiment. apparently this is all tied to the security level. at typical security (medium) the router automatically opens ports for skype, xbox, torrent, etc. as the applications ask for them. at maximum security (high) only necessary and related ports are opened. attempts to use BitTorrent are blocked and no new entries are seen in the Port Forwarding page.
a decent user guide,or even a somewhat knowledgeable phone tech, could have saved a lot of time and confusion.
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CC_John
Retired Employee
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1.9K Messages
10 years ago
Hi megaabite. The Comcast gateway does ship with all ports available for application assignments based on customer choice. However there no automatic port forwarding rules set on any device. Port forwarding rules are unique to each customer's network and are manually configured and enabled.
To make changes to your current port forwarding entries: sign into the gateway, click the advanced tab then click the port forwarding tab, click the edit button. this will open the menu for that entry,, make the necessary changes and the click save at the bottom of the page, before navigating to a different page. To remove a port forwarding entry, click the on line of the desired entry, then click when prompted for confirmation. This will remove the desired entry.
If the device does not respond to the configuration commands we can have it replaced.
Thank You
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megaabite
New Member
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3 Messages
10 years ago
> However there no automatic port forwarding rules set on any device.
I set up one forwarding port for remote desktop which works fine. But, on the port forwarding page, there are multiple settings for Xbox, Skype, and one for uTorrent. I am the only person with the new password. I DID NOT CREATE THOSE ENTRIES.
> To make changes to your current port forwarding entries: sign into the gateway, click the advanced tab then click the ...
Yes,works fine on entries that I make. Tried that on the entries for Xbox, Skype,uTorrent. I CANNOT DISABLE OR DELETE THOSE ENTRIES.
In fact, the remote desktop entry I had made was deleted while attempting to remove the unwanted entries. (Remote Desktop entry was at the top of the page. uTorrent was at the bottom. Remote Desktop was probably not accidently deleted.)
Sorry, but your information is wrong. I can share a teamviewer seesion, or whatever, with you that demonstrates the described behavior
Model: DPC3939B
Vendor: Cisco
Hardware Revision: 1.0
Serial Number XXXX76291
Processor Speed: 447.28 MHz
DRAM: 512 Mb
Flash: 128MKb
do not see a firmware version number
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