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".
45 -P Set the password prompt. Sshpass searched for this prompt in the
47 program's output to the TTY as an indication when to send the
48 password. By default sshpass looks for the string "assword:"
49 (which matches both "Password:" and "password:"). If your
50 client's prompt does not fall under either of these, you can
51 override the default with this option.
52 -v Be verbose. sshpass will output to stderr information that
54 should help debug cases where the connection hangs, seemingly
55 for no good reason.
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58 First and foremost, users of sshpass should realize that ssh's insis‐
59 tance on only getting the password interactively is not without reason.
60 It is close to impossible to securely store the password, and users of
61 sshpass should consider whether ssh's public key authentication pro‐
62 vides the same end-user experience, while involving less hassle and
63 being more secure.
64 The -p option should be considered the least secure of all of sshpass's
66 options. All system users can see the password in the command line
67 with a simple "ps" command. Sshpass makes a minimal attempt to hide the
68 password, but such attempts are doomed to create race conditions with‐
69 out actually solving the problem. Users of sshpass are encouraged to
70 use one of the other password passing techniques, which are all more
71 secure.
72 In particular, people writing programs that are meant to communicate
74 the password programatically are encouraged to use an anonymous pipe
75 and pass the pipe's reading end to sshpass using the -d option.
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78 As with any other program, sshpass returns 0 on success. In case of
79 failure, the following return codes are used:
80 1 Invalid command line argument
82 2 Conflicting arguments given
84 3 General runtime error
86 4 Unrecognized response from ssh (parse error)
88 5 Invalid/incorrect password
90 6 Host public key is unknown. sshpass exits without confirming the
92 new key.
93 In addition, ssh might be complaining about a man in the middle attack.
95 This complaint does not go to the tty. In other words, even with ssh‐
96 pass, the error message from ssh is printed to standard error. In such
97 a case ssh's return code is reported back. This is typically an unimag‐
98 inative (and non-informative) "255" for all error cases.
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101 Run rsync over SSH using password authentication, passing the password
102 on the command line:
103 rsync --rsh='sshpass -p 12345 ssh -l test' host.example.com:path .
105 To do the same from a bourne shell script in a marginally less exposed
107 way:
108 SSHPASS=12345 rsync --rsh='sshpass -e ssh -l test' host.exam‐
110 ple.com:path .
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113 Sshpass is in its infancy at the moment. As such, bugs are highly pos‐
114 sible. In particular, if the password is read from stdin (no password
115 option at all), it is possible that some of the input aimed to be
116 passed to ssh will be read by sshpass and lost.
117 Sshpass utilizes the pty(7) interface to control the TTY for ssh. This
119 interface, at least on Linux, has a misfeature where if no slave file
120 descriptors are open, the master pty returns EIO. This is the normal
121 behavior, except a slave pty may be born at any point by a program
122 opening /dev/tty. This makes it impossible to reliably wait for events
123 without consuming 100% of the CPU.
124 Over the various versions different approaches were attempted at solv‐
126 ing this problem. Any given version of sshpass is released with the
127 belief that it is working, but experience has shown that these things
128 do, occasionally, break. This happened with OpenSSH version 5.6. As of
129 this writing, it is believed that sshpass is, again, working properly.
130Lingnu Open Source Consulting April 25, 2015 SSHPASS(1)