Please send bugreports to netfilter-devel.
Ron Lai wrote:
Hi all,
My 2.6.22.6 Linux box is acting as a NAT device. I found that a NATted
FTP client is having problem using active mode to connect to a outside
FTP server. (Passive mode works fine.)
From the trace I could see that the PORT command from the FTP client is
correctly modified by the Linux box to use the converted NAT address.
However, the confirmation from the server never makes it to the client
and the client just keeps retransmitting the PORT command packet.
Do you mean it never makes it to the FTP client or to the machine
where the client is running?
The interesting part is that active mode can work if the length of the
actual IP address of the client is the same as the length of the
converted NAT address. It looks like if there is no TCP sequence number
modification by the Linux box, the FTP connection can work properly in
active mode. I am suspecting that there may a problem in the TCP
sequence number tracking in the kernel modules.
The same settings work fine when I try with Linux 2.6.15 loading
ip_nat_ftp.ko and ip_conntrack_ftp.ko. Did I miss anything in
configuring the Linux 2.6.22.6 box?
Works fine here. Please post the dump, ideally from a box in the
middle.
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