Saturday, June 9, 2018

How do I login over ssh without using password less RSA / DSApublic keys?

Linux system Admins  normally login to the linux  servers either supplying a password,
or using keybased authentication. sshpass is a tool which allows us to automatically
supply password to the command prompt so that automated scripts can be run as desired
by users. sshpass supplies password to ssh prompt using dedicated tty , fooling ssh to
believe that a interactive user is supplying password.

Install sshpass under Debian / Ubuntu Linux

Type the following command:
$ sudo apt-get install sshpass

Install sshpass under RHEL/CentOS Linux

$ sudo yum install sshpass

If you are using Fedora Linux, type:
$ sudo dnf install sshpass

Install sshpass under Arch Linux

$ sudo pacman -S sshpass

Install sshpass under OpenSUSE Linux

$ sudo zypper install sshpass

Install sshpass under FreeBSD Unix

To install the port, enter:
# cd /usr/ports/security/sshpass/ && make install clean
To add the package, run:
# pkg install sshpass

Getting Help :
# sshpass -h
Usage: sshpass [-f|-d|-p|-e] [-hV] command parameters
  • -f filename   Take password to use from file
  • -d number Use number as file descriptor for getting password
  • -p password   Provide password as argument (security unwise)
  • -e         Password is passed as env-var "SSHPASS" With no parameters – password will be taken from stdin
  • -h         Show help (this screen)
  • -V         Print version information
At most one of -f, -d, -p or -e should be used

How do I use sshpass in Linux or Unix?

Login to ssh server called with password called redhat@1234
$ sshpass -p 'redhat@1234' ssh

For shell script you may need to disable host key checking:
$ sshpass -p 'redhat@1234' ssh -o StrictHostKeyChecking=no


$sshpass -p 'redhat@1234' ssh  "uptime"

Sample output
01:04:35 up 126 days,  3:34, 2 users, load average: 0.50, 0.54, 0.55

Reading password from file

Another option is to read password from file using the -f option.
The syntax is:
sshpass -f fileNameHere ssh user@server

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