What ports to forward in router?

[rikytik]

Tho I looked at help files, I even missed this.

PASV port range
When the PASV command is used Serv-U opens a data socket and tells the client where it can connect. The data socket is used for directory listings and file transfers in passive mode. By default this port range is blank which means the server will acquire a new listening socket with a random port number between 1024 and 65535 for every passive mode transfer.

Using this range Serv-U will limit which ports are used. This is very important for firewall configurations that limit incoming connections? port usage. When blank Serv-U allows Windows to pick the port number, when a range is entered Serv-U will set up a fixed number of sockets on these ports and use these to service passive mode data transfers.

If this option is used the idea is to use a range of ports that are available, i.e. above 1024, something with high port numbers like 23580-23590. The number of ports to designate depends on a few factors: If you allow FXP (direct server-to-server transfers) you need as many ports as you get concurrent FXP clients otherwise the server may not be able to figure out what passive mode connection should be routed to which FTP session. If you allow multiple connections from the same client IP you ideally need as many ports as you get concurrent connections from the same IP. This again is so Serv-U can distribute requests over the available sockets and figure out what connection should go to which session. If neither of the two applies then in theory a single port would do the job, though it is better to use at least 3 ports or so to distribute requests and make lookups faster (the lookups hook the client connection up with an FTP session). On NT/W2K a good average number would be something like 15 ports, on Win9x/ME use no more than 5 ports since that OS is 'socket challenged' and quickly runs out of available sockets. Serv-U will not allow more than 50 ports to be used for the passive mode range regardless of your settings, since that many start to impair performance. Anywhere close to 50 ports should really never be needed, even on the busiest of servers.