Ok,I finally figure out what goes wrong about flashfxp by coding a little sock5 proxy to test flashfxp.
after the authorization to the socks proxy,flashxp sends this request string to the socks proxy.
"5 1 0 3 14 50 49 56 46 51 56 46 50 49 55 46 49 52 50 11 199"
Let's look at the first 4 bytes:
5 is the sock5 version number
1 is the "CONNNECT" Method
0 is Reserved Byte
3 is Domain Name -> Here is the problem cause
First of all,the socks proxy and the ftp server are all IP V4 address, I don't know why flashfxp will use 3.Even it's ok to do so,
let's check the socks proxy reply.Since flashfxp's request uses 3,
so the sock proxy reply with "5 0 0 3 0 0 0 0 0 0" to flashfxp,the the above problem rises.If the sock proxy reply with "5 0 0 1 0 0 0 0 0 0",flashfxp will work fine.
cuteftp,ws_ftp and leapftp will only use "5 0 0 1 X X X....." in the request if both sock proxy and ftp server address are in IP v4 format.I doubt why flashfxp acts like that.The sock is ok to reply "5 0 0 1 X X X X ......",but if it does it,the sock proxy may have problem with sock udp protocol program.I have test over 5 different ftp clients,and only flashfxp's request is so different.
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