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Old August 18, 2007, 08:22 AM
Haz Haz is offline
Join Date: Aug 2007
Posts: 4

Originally Posted by bushwhacker View Post
- no such thing as blocking FTP function - it's just more 1s and 0s through TCP.
- Telus does block some ports, however I doubt they are blocking 10s of thousands .... which any of can be used for FTP.

I'm betting it's a configuration problem with setting it up. It is so easy to overlook/miss any one of a number of details such that accessing the FTP from the WAN doesn't work.
Unfortunately its not just 1's and 0's... Well it is, but there is more to it than that. There is something called Stateful Packet Inspection or SPI in place. What this is able to do is inspect the packet headers of any data moving in any direction on any given port (TCP or UDP).

Depending on the rules defined by the administrator, an SPI router/switch can be told to disallow packets with headers matching the FTP spec on ANY port. It can be configured to either drop the connection entirely or purposely strip the header and rewrite it and or garble it.

This is how corporate intranets with internet access control what you can do from your workstation. They usually implement it in conjunction with a proxy server, but it doesn't have to be implemented this way.

Im not a TELUS customer however, so I cannot immediately verify if they are utilizing SPI for their consumer DSL connections. But I will look into it.

At this point in time, I am thinking that the issue with access FTP on the LX NAS is something to do with the unit itself since I cannot get it work either, and my ISP does not BLOCK/SPI ANYTHING. I can host an FTP server on my box and access it fine from outside my router with proper port forwarding setup. But I cannot access the FTP on the LX at all even with proper port forwarding setup.

This is something to do with the way the LX handles routed packets or something goofy like that. VERY POOR design IMO.
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