Well, my problem is as this:
I run a glFTPd for my ftp server.... to connect to this server from inside the network, nothing goes wrong, everything well..... but, the problem: when i try to connect from outside the network (let's say from school, friends house) it's refused..... how is this happening??

Some information:

erik@debian:~$ netstat -a | grep ftp
tcp 0 0 *:glftpd *:* LISTEN

erik@debian:~$ grep -v '#' /etc/services | grep ftp
ftp-data 20/tcp
ftp 21/tcp
tftp 69/udp
sftp 115/tcp
ftps 990/tcp
glftpd 21/tcp

erik@debian:~$ grep -v '#' /etc/hosts.allow
glftpd: ALL

erik@debian:~$ grep -v '#' /etc/network/interfaces

auto lo
iface lo inet loopback

auto eth0
iface eth0 inet static
address 192.168.2.171
netmask 255.255.255.0
broadcast 192.168.2.255
gateway 192.168.2.1

debian:/home/erik# ifconfig
eth0 Link encap:Ethernet HWaddr 00:50:FC:A2:6D5
inet addr:192.168.2.171 Bcast:192.168.2.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:21171 errors:0 dropped:0 overruns:0 frame:0
TX packets:20249 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:3093648 (2.9 MiB) TX bytes:15623052 (14.8 MiB)
Interrupt:17 Base address:0xec00

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:3559 errors:0 dropped:0 overruns:0 frame:0
TX packets:3559 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:853426 (833.4 KiB) TX bytes:853426 (833.4 KiB)

Well i think that's all you guys should know
btw, i also use a router... i forwarded port 21 to my computer, also it can't be a router problem since I run a serv-u ftp server on windows, also using port 21......

I've been struggeling with this for some time... it's making me sick

That's most likely your problem, you can't forward port 21 to two different addresses behind a router/firewall to two different machines.. its either one of the other. Most likely if you have it setup to your Windows box, its probably first on the list in your router configuration so its defaulting to it over any others. Or you can just simply setup one to listen to port 2121 and the other 21.. etc.

Hmmmz... no I explained it wrong
it's like... i have one system with dual boot..... windows xp and linux.... if i run linux, i can't get to windows, so then serv-u isn't running..... so then the port should be forwarded correctly... or am i getting this wrong?

do both your windows side and linux side pull the same IP?

if they are not pulling the same IP, then when you dual boot you are pointing to the wrong IP, thus the forwarding is not working.

no, both the same ip.... but, i made some progress i removed it completely......... en reinstalled... en yes! now it's working (though i don't know what i was doing different :S)

now... i only have to get xinerama to work.... and winxp can be deleted (wel, some printer drivers etc still aren't working )