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Old 20.09.2008, 20:57
the traveler the traveler is offline
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Re: Swisscom Port Blocking?

Good point about FTP being old and not initially intended for firewalls. I hadn't really dug into the inner workings of FTP (at least not for a long time). As far as ports and NATs go, here is my setup: the internet connection is ADSL over a phone line that hooks to the modem swisscom provided me for free. THe modem should be in bridging mode and the ACLs on it are "any, any" or allow everything. Next I've alternated between testing with my linksys router and port forwarding, the router with my computer in the DMZ, or my computer directly hooked to the ethernet port of the modem. In all cases, no incomming connections can be properly established.

In the end, I'm just trying to transfer a file, but I figured FTP would also work for port testing. I also did a few tests with a TFTP server, but got strange results and need to test that a little further.

I'll probably try another factory reset on the modem and hook my pc directly to it, bypassing the router to see if I get any further. The FTP program I use allows you to set what ports it will use for connection creation and what range for data transfer. I've tried some well known ports under 1024, random ones around 4000 and some others around 50000.

The other strange thing with the modem is that from the web interface I can only view and change settings until the modem trains up and gets the firmware image from Swisscom. After that, if I want to change settings I have to telnet into the modem. I've confirmed that by issuing a "write mem" command to the modem, it will save my changes even after reboot and receiving the Swisscom firmware.

Unfortunately, I don't have another PC here handy to test with (could be something stupid), but I should shortly.

Can anyone think of what else other than my modem or Swisscom themselves that could be blocking incomming connections?

Can anybody recommend a better modem?
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