vsftpd behind NAT problem

[Nikos I. Gabrielides]

Hi all,

I am using an FTP Server behind NAT (vsftpd v1.2.0-5 on 
Fedora Core 1 kernel 2.4.22-1.2115.nptl). 
The server is behind NAT router (Zyxel Prestige 660R-61).
I have problems connecting to it from a computer outside.

I am looking for a way to solve this at FTP Server side.

I have enabled DynDNS and port forwarding for the needed port
ranges (20:21, 7727:7777) on the ADSL router.
But I cannot connect from the outside.

Please, somebody, tell me how can I troubleshoot the problem.
(where do i look for 'syslog' ?).
Or, even better, do you guys see any solution for this ?

Thx in advance

/ganick

PS:
My cofiguration is as follows:


** iptables rules **
...
-A RH-Firewall-1-INPUT -p udp -m udp --dport 20 -j ACCEPT
-A RH-Firewall-1-INPUT -p udp -m udp --dport 7727:7777 -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m tcp --dport 20 -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m tcp --dport 7727:7777 -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m tcp --dport 21 -j ACCEPT
...
(probably udp holes are not needed)

** vsftpd.conf**
listen=YES
anonymous_enable=YES
ftp_username=ftp
write_enable=NO
anon_upload_enable=NO
anon_mkdir_write_enable=NO
anon_other_write_enable=NO
anon_world_readable_only=YES
anon_max_rate=10240
idle_session_timeout=300
ascii_download_enable=NO
ascii_upload_enable=NO
connect_from_port_20=NO
port_enable=YES
hide_ids=NO
max_per_ip=0
local_root=/var/ftp
nopriv_user=nobody
# assist NAT firewall
pasv_enable=YES
pasv_min_port=7727
pasv_max_port=7777
log_ftp_protocol=YES
syslog_enable=YES
ftpd_banner=Welcome to ganick's FTP sever. Behave!