Pass a password to ssh in pure bash

Question

I want to pass a password to ssh using a bash script  Yes  I know that there are ssh keys that I could use  but this is not what I intend    I found some solutions that were using expect but since it is not a standard bash tool I am wondering if I can do this using pipes   Can someone explain to me  why exactly something like this   echo  password n    ssh somehost com   or  ssh somehost com  lt  echo  password n     doesn t work  Is there any possibility to make it work  Maybe executing ssh as a different process  obtaining its PID and then sending a string directly to it

User · Accepted Answer

Since there were no exact answers to my question, I made some investigation why my code doesn't work when there are other solutions that works, and decided to post what I found to complete the subject.
As it turns out:

"ssh uses direct TTY access to make sure that the password is indeed issued by an interactive keyboard user." sshpass manpage

which answers the question, why the pipes don't work in this case. The obvious solution was to create conditions so that ssh "thought" that it is run in the regular terminal and since it may be accomplished by simple posix functions, it is beyond what simple bash offers.

User · Answer

You can not specify the password from the command line but you can do either using ssh keys or using sshpass as suggested by John C  or using a expect script   To use sshpass  you need to install it first  Then  sshpass -f  lt  printf   s n  your password  ssh user hostname   instead of using sshpass -p your password  As mentioned by Charles Duffy in the comments  it is safer to supply the password from a file or from a variable instead of from command line    BTW  a little explanation for the  lt  command  syntax   The shell executes the command inside the parentheses and replaces the whole thing with a file descriptor  which is connected to the command s stdout  You can find more from this answer https   unix stackexchange com questions 156084 why-does-process-substitution-result-in-a-file-called-dev-fd-63-which-is-a-pipe

[linux] Pass a password to ssh in pure bash

Examples related to linux

Examples related to bash

Examples related to pipe