[NCLUG] debugging ftp iptables

[Matt Rosing]

 >-I can upload a small file from my laptop to the server just fine (536
 >bytes works, 537 fails). The file I'm trying to upload is 2500 bytes.

I found something interesting. 536 bytes is the default packet size, 
except the stock client thinks it's 4096 or something. Ftp should start 
off with some transaction to decide what the transfer size is but it 
doesn't apprear to do this. Or is it possible that my firewall is 
interfering with that transaction? When the server sends a RST packet 
does nf_conntrack_ftp send that packet through to the client?

Anyway, I also found a windows ftp switch that can specify the buffer 
size. So I set it to 500 bytes and now ftp works fine.

Now, for a really stupid question, how do I modify ftp.exe in windows to 
use the -w:500 option? or replace it with something else? I do linux so 
am not at all familiar with this (I know, this isn't the right place to 
ask). It's a dot-net application if that means anything.