1SSHPASS(1) Sshpass User Manual SSHPASS(1)
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6 sshpass - noninteractive ssh password provider
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9 sshpass [-ffilename|-dnum|-ppassword|-e] [options] command arguments
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12 This manual page documents the sshpass command.
13 sshpass is a utility designed for running ssh using the mode referred
15 to as "keyboard-interactive" password authentication, but in non-inter‐
16 active mode.
17 ssh uses direct TTY access to make sure that the password is indeed
19 issued by an interactive keyboard user. Sshpass runs ssh in a dedicated
20 tty, fooling it into thinking it is getting the password from an inter‐
21 active user.
22 The command to run is specified after sshpass' own options. Typically
24 it will be "ssh" with arguments, but it can just as well be any other
25 command. The password prompt used by ssh is, however, currently hard‐
26 coded into sshpass.
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29 If no option is given, sshpass reads the password from the standard
30 input. The user may give at most one alternative source for the pass‐
31 word:
32 -ppassword
34 The password is given on the command line. Please note the sec‐
35 tion titled "SECURITY CONSIDERATIONS".
36 -ffilename
38 The password is the first line of the file filename.
39 -dnumber
41 number is a file descriptor inherited by sshpass from the run‐
42 ner. The password is read from the open file descriptor.
43 -e The password is taken from the environment variable "SSHPASS".
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47 First and foremost, users of sshpass should realize that ssh's insis‐
48 tance on only getting the password interactively is not without reason.
49 It is close to impossible to securely store the password, and users of
50 sshpass should consider whether ssh's public key authentication pro‐
51 vides the same end-user experience, while involving less hassle and
52 being more secure.
53 The -p option should be considered the least secure of all of sshpass's
55 options. All system users can see the password in the command line
56 with a simple "ps" command. Sshpass makes a minimal attempt to hide the
57 password, but such attempts are doomed to create race conditions with‐
58 out actually solving the problem. Users of sshpass are encouraged to
59 use one of the other password passing techniques, which are all more
60 secure.
61 In particular, people writing programs that are meant to communicate
63 the password programatically are encouraged to use an anonymous pipe
64 and pass the pipe's reading end to sshpass using the -d option.
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67 As with any other program, sshpass returns 0 on success. In case of
68 failure, the following return codes are used:
69 1 Invalid command line argument
71 2 Conflicting arguments given
73 3 General runtime error
75 4 Unrecognized response from ssh (parse error)
77 5 Invalid/incorrect password
79 6 Host public key is unknown. sshpass exits without confirming the
81 new key.
82 In addition, ssh might be complaining about a man in the middle attack.
84 This complaint does not go to the tty. In other words, even with ssh‐
85 pass, the error message from ssh is printed to standard error. In such
86 a case ssh's return code is reported back. This is typically an unimag‐
87 inative (and non-informative) "255" for all error cases.
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90 Run rsync over SSH using password authentication, passing the password
91 on the command line:
92 rsync --rsh='sshpass -p 12345 ssh -l test' host.example.com:path .
94 To do the same from a bourne shell script in a marginally less exposed
96 way:
97 SSHPASS=12345 rsync --rsh='sshpass -e ssh -l test' host.exam‐
99 ple.com:path .
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102 Sshpass is in its infancy at the moment. As such, bugs are highly pos‐
103 sible. In particular, if the password is read from stdin (no password
104 option at all), it is possible that some of the input aimed to be
105 passed to ssh will be read by sshpass and lost.
106 Sshpass utilizes the pty(7) interface to control the TTY for ssh. This
108 interface, at least on Linux, has a misfeature where if no slave file
109 descriptors are open, the master pty returns EIO. This is the normal
110 behavior, except a slave pty may be born at any point by a program
111 opening /dev/tty. This makes it impossible to reliably wait for events
112 without consuming 100% of the CPU.
113 Over the various versions different approaches were attempted at solv‐
115 ing this problem. Any given version of sshpass is released with the
116 belief that it is working, but experience has shown that these things
117 do, occasionally, break. This happened with OpenSSH version 5.6. As of
118 this writing, it is believed that sshpass is, again, working properly.
119Lingnu Open Source Consulting August 6, 2011 SSHPASS(1)