DCC was way to send files and chat without having IRC server in the between. It’s not very common nowadays and what is done nowadays is uploading images etc. to social media services or web servers or using other file transfer protocols.

Here are some reasons to not use it:

  • There is no proper standard or if there is, no one follows it, all clients speak their own dialects and may be unable to communicate with other clients. Not all clients even implement the same features.
  • NAT and firewalls break it
    • As DCC requires port on sending/hosting side, it must be opened in firewall and if there is NAT which there is in most of situations nowadays, the port must be forwarded. Most of average users have no idea how to do the latter if even the first.
  • The only place where most of people see it is spam. The only thing lately where people have seen is two attacks which @grawity has documented here

Disabling DCC

This depends on your client and I am only able to give instructions for three:

  • WeeChat: “/plugin unload xfer” and “/set weechat.plugin.autoload *,!xfer
    • The option in second command can be also be used to not automatically load other plugins, I personally use /set weechat.plugin.autoload alias,exec,irc,perl,python,script,trigger,logger. The *,!xfer simply means load everything else than xfer.
  • HexChat: “/ignore *!*@* DCC
  • ZNC & clients behind it: “/znc *controlpanel addctcp $me DCC