My network connects to the Internet via a masquerading router. This router runs RedHat Linux 9, and runs the vsftpd that comes with RHL9. My firewall/routing script is set up to allow traffic through ports 20 (ftp-data), 21 (ftp-control) and any port 1024-max.
FTP uploading from the Internet works fine for small files, but when I send a lot of them or a large one something weird happens. Sometimes my FTP transfer just stalls but I can still log in to the router with SSH and it still lets HTTP traffic through to my webserver. But most of the time when my FTP transfer stalls SSH and HTTP stop working aswell.
I attempted to fix the problem by modprobing ip_conntrack_ftp and ip_nat_ftp, but that doesn't seem to do much good either.
I anyone here has vsftpd running on RHL9 without problems with large uploads, or knows why my router seems to lock up, or has any other usefull information whatsoever, I'd love to hear (well, read, but you take my meaning) it.

TIA, Rogier

Oh, some more info that might be usefull
SSH sessions seem to time out waiting for authentication after FTP stalls (SSH works just fine otherwise).
The vsftpd log file shows absolutely nothing, I should probably make it log more stuff though.
HTTP is forwarded like so:
iptables -t nat -A PREROUTING -i ppp0 -p tcp --dport 80 -m state --state NEW -j DNAT --to-destination 10.0.0.3:80
iptables -t filter -A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT
(or something like that, I'm not at home and SSH won't let me in no more since my large FTP transfer failed, so this is from memory).