when you send a file to a user your mirc sends a hidden message across the irc server to the reciever of the file this is the format

DCC SEND filename ipaddress port filesize

This is a /CTCP, which is a infact a /MSG with a $chr(1) leading and trailing the text

so say your ip address was and your going to send the file "bob.txt" which is 1024 bytes in size on port 9999 then your sending this....
//msg reciversnick $chr(1) $+ DCC SEND "bob.txt" 16909060 9999 1024 $+ $chr(1)

16909060 is the 32bit IP value of

So knowing that, you now know that, be you sent or reciving a file, you get a message like this or send a message like this.
Said message goes to the irc server, BT is monitoring connections and when it detects a message in this nature it terminates the connection.
Alot of people well have seen the "user suchand such sending you a file on (" or something like that, this is a polite let you know /notice mirc sends just prior to sending the DCC SEND message outlined above. From what i have gathered the connection is broken the instant the DCC SEND is detected, you do not receive the DCC SEND so you know a file should be coming becuase you saw the notice, that was however not actually part of the file send.

[edit: oops pushed submit]

There is also apparently some other dcc's BT catches , i think
$chr(1) $+ DCC CHAT chat longip port $+ $chr(1)
is also caught and terminates your irc server connection

It should be noted an actual DCC connection can be made by you, should you be connecting to a leistening port dcc chat/send/fserve as i have tested this with a BT customer, i was able to connect to his and he to mine.

Last edited by DaveC; 09/12/06 11:32 PM.