FTP server using passive ports

pugilares wrote:
As your server works in passive mode - did you setup ftp masquerade? You say that "the Duo doesn't use its passive ports, just the normal one, as the Ultra pops in on the passive ports only" - what do you mean by that - what says your client?

To clarify, both servers enter passive mode, due to being behind a firewall in my router. The thing is that I haven't forwarded the passive ports for the Duo, thats why I assume it's using the original port (port 21)

I've set up masquerade on both servers as the internal IP, to be able to access them locally. This works fine for the Duo, and the Ultra. The servers enter passive mode even if I masquerade them as the external IP or my DynDNS domain.

StephenB wrote:

Slasky - what client are you using? With filezilla you can see what passive port is being engaged (though you need to do the math, since it gives you the high and low byte of the port number separately). My Duo V1 definitely uses the passive port. If you are checking this from work, perhaps the firewall is acting as an FTP proxy for the Duo. You could confirm this by changing it to a non-standard port (21 being the normal FTP port). Or see if you get the same behavior when connecting locally. pugilares wrote: wrote: As your server works in passive mode - did you setup ftp masquerade? I use filezilla, and don't configure the masquerade. Filezilla will detect the private address and substitute the address used on the IP layer. If I set the masquerade, then I can't connect inside my LAN (since FileZilla won't substitute a private address for a public one)

I'm using FileZilla and numbers popping up after the IP-address are 55 and 119 on the Ultra, and 55 and 99 on the Duo

I've been thinking about the FTP proxy as you mention, planning on testing if I set the standard FTP port on the Ultra, just to check if that passes through. If I can't fix this problem, I guess it's gonna be a trade-off on which FTP server that would be accessible from work.

If it's needed for more thorough exlpanation, I can post pics of my router config and port forwarding

EDIT: I tried setting the Ultra with port 21, and it passed right through. So it's either the firewall who can't parse the port correctly, or it's the FTP server who can't operate on port 27 without using the passive ports

Thanks again for the answers