- Fix operation of ABOR
  - Need to select on both channels when copying data.
  - RFC 959 4.1.3 says the connection aborted with error 426.
  - The response from ABOR should be 226.
  - See also notes on telnet "Interrupt Process" signal.

- Tests:
  - u+s g+s +t permissions on listings
  - Proper CHROOT/SOFTCHROOT/LOCKHOME behavior
  - LOGREQUESTS on/off
  - LOGRESPONSES on/off
  - \377 escapes on output
  - CWD into various mode directories
  - RETR from/STOR to various mode directories

- Write a twoftpd log tailing program to output timeout stats and the
  like.

- Look into spying on the status of the servers:
  - exporting status through environment or modifying the command-line
  - get pids by looking for children of tcpserver

- Implement "FEAT" command.

- Build-in support for gzipping content on-the-fly with zlib:
  - If client requests X.gz, and X exists, open and compress

- Build-in support for gunzipping content on-the-fly with zlib:
  - If client requests X, and X.gz exists, open and decompress

- Build-in support for recursive retrieval producing a tar file internally.

- Add IPv6 support.
