passh

NOTE: The pty related code is stolen from the APUE book.

compile

$ cc -o passh passh.c

usage

Usage: passh [OPTION]... COMMAND...

  -c <N>          Send at most <N> passwords (0 means infinite. Default: 0)
  -C              Exit if prompted for the <N+1>th password
  -h              Help
  -i              Case insensitive for password prompt matching
  -n              Nohup the child (e.g. used for `ssh -f')
  -p <password>   The password (Default: `password')
  -p env:<var>    Read password from env var
  -p file:<file>  Read password from file
  -P <prompt>     Regexp (BRE) for the password prompt
                  (Default: `[Pp]assword: \{0,1\}$')
  -l <file>       Save data written to the pty
  -L <file>       Save data read from the pty
  -t <timeout>    Timeout waiting for next password prompt
                  (0 means no timeout. Default: 0)
  -T              Exit if timed out waiting for password prompt
  -y              Auto answer `(yes/no)?' questions

Report bugs to Clark Wang <dearvoid@gmail.com>

supported platforms

Tested on:

OpenWRT 15.05.1, ramips/mt7620 (on Newifi Mini, or Lenovo Y1 v1)
Debian Linux 8, x86_64 (Jessie)
macOS 10.12 (Sierra)
Cygwin, x86_64 (on Windows 7)
FreeBSD 11.1, x86_64
AIX 7.2, ppc64le (added in issue #7)

why i wrote passh

I got a Newifi Mini router and installed OpenWRT on it. I want the router to be my SOCKS proxy so I run ssh -D 8888 user@host automatically at boot time but the SSH server only supports password auth. On Linux I would use Expect to automate ssh but OpenWRT does not install Expect by default and my router does not have enough storage for the extra Tcl and Expect packages.

Then I tried sshpass but sshpass seems more like a nice hack and it's broken by design. See following example on a Linux system:

 $ tty
 /dev/pts/18                                      // now we're on pts/18
 $ sshpass bash --norc
 bash: cannot set terminal process group (-1): Inappropriate ioctl for device
 bash: no job control in this shell
 bash-4.4# tty
 /dev/pts/18                                      // the bash's stdin is also connected to pts/18
 bash-4.4# ps p $$
    PID TTY      STAT   TIME COMMAND
  37151 pts/36   Ss+    0:00 bash --norc          // but the controlling terminal is pts/36
 bash-4.4# ps t pts/36
    PID TTY      STAT   TIME COMMAND
  37151 pts/36   Ss+    0:00 bash --norc
  37154 pts/36   R+     0:00 ps t pts/36
 bash-4.4#

Now let's try passh:

 $ tty
 /dev/pts/18                                      // now we're on pts/18
 $ passh bash --norc
 bash-4.4# tty
 /dev/pts/36                                      // the bash's stdin is connected to the new pts/36
 bash-4.4# ps p $$
    PID TTY      STAT   TIME COMMAND
  37159 pts/36   Ss     0:00 bash --norc          // pts/36 is its controlling terminal
 bash-4.4# ps t pts/36
    PID TTY      STAT   TIME COMMAND
  37159 pts/36   Ss     0:00 bash --norc
  37162 pts/36   R+     0:00 ps t pts/36
 bash-4.4#

See sshpass-broken.md for more sshpass is broken examples.

examples

sshpass is better in its own way.

For example, you can use rsync + sshpass like this:

 $ rsync -e 'sshpass -p password ssh' file user@host:/dir

But with passh you have to:

 $ passh -p password rsync -e ssh file user@host:/dir

Another example, with sshpass you can:

 $ echo date | sshpass -p password ssh user@host bash