NAME
sshpass - noninteractive ssh password provider
SYNOPSIS
sshpass [-ffilename|-dnum|-ppassword|-e] [options] command arguments
DESCRIPTION
This manual page documents the sshpass command.
sshpass is a utility designed for running ssh using the mode referred
to as "keyboard-interactive" password authentication, but in non-
interactive mode.
ssh uses direct TTY access to make sure that the password is indeed
issued by an interactive keyboard user. Sshpass runs ssh in a dedicated
tty, fooling it into thinking it is getting the password from an
interactive user.
The command to run is specified after sshpass’ own options. Typically
it will be "ssh" with arguments, but it can just as well be any other
command. The password prompt used by ssh is, however, currently
hardcoded into sshpass.
Options
If not option is given, sshpass reads the password from the standard
input. The user may give at most one alternative source for the
password:
-ppassword
The password is given on the command line. Please note the
section titled "SECURITY CONSIDERATIONS".
-ffilename
The password is the first line of the file filename.
-dnumber
number is a file descriptor inherited by sshpass from the
runner. The password is read from the open file descriptor.
-e The password is taken from the environment variable "SSHPASS".
SECURITY CONSIDERATIONS
First and foremost, users of sshpass should realize that ssh’s
insistance on only getting the password interactively is not without
reason. It is close to impossible to securely store the password, and
users of sshpass should consider whether ssh’s public key
authentication provides the same end-user experience, while involving
less hassle and being more secure.
The -p option should be considered the least secure of all of sshpass’s
options. All system users can see the password in the command line
with a simple "ps" command. Sshpass makes no attempt to hide the
password, as such attempts create race conditions without actually
solving the problem. Users of sshpass are encouraged to use one of the
other password passing techniques, which are all more secure.
In particular, people writing programs that are meant to communicate
the password programatically are encouraged to use an anonymous pipe
and pass the pipe’s reading end to sshpass using the -d option.
RETURN VALUES
As with any other program, sshpass returns 0 on success. In case of
failure, the following return codes are used:
1 Invalid command line argument
2 Conflicting arguments given
3 General runtime error
4 Unrecognized response from ssh (parse error)
5 Invalid/incorrect password
6 Host public key is unknown. sshpass exits without confirming the
new key.
In addition, ssh might be complaining about a man in the middle attack.
This complaint does not go to the tty. In other words, even with
sshpass, the error message from ssh is printed to standard error. In
such a case ssh’s return code is reported back. This is typically an
unimaginative (and non-informative) "255" for all error cases.
EXAMPLES
Run rsync over SSH using password authentication, passing the password
on the command line:
rsync --rsh=’sshpass -p 12345 ssh -l test’ host.example.com:path .
To do the same from a bourne shell script in a marginally less exposed
way:
SSHPASS=12345 rsync --rsh=’sshpass -e ssh -l test’
host.example.com:path .
BUGS
Sshpass is in its infancy at the moment. As such, bugs are highly
possible. In particular, if the password is read from stdin (no
password option at all), it is possible that some of the input aimed to
be passed to ssh will be read by sshpass and lost.