script to ssh to a unix server

Question

It will be helpful if somebody could tell me how to connect to a unix server using username and password as arguments.my username and password is "anitha".

How can i create a shell script which automatically connect to my unix server with this username and password?

Connect? How do you want to connect? http? ssh? ...? If you want to open a ssh connection don't use name/passwd but ssh keys instead. — Ocaso Protal
– Ocaso Protal, Commented May 24, 2011 at 9:20

eush77 · Accepted Answer · 2014-11-21 15:35:37Z

5

I guess you want to remotely connect to your *nix server from network. Base on my guess, to:

connect to remote *nix server, everybody is using SSH

ssh anitha@anitha ip-to-unix-server

automatically connect, write simple bash shell wrap around your ssh connect command and do something, not suggested, you should use ssh password less login (aka public/private key)

#!/usr/bin/env bash
ip=172.16.0.1   #replace 172.16.0.1 with your unix server's ip
username=anitha #your ssh username
password=anitha #your ssh password
command=who     #what do you want to do with remote server
arguments=      #arguments for your command
expect -c 'spawn ssh $username@$ip ; expect password ; send "$password\n" ; interact'

connect without typing password, you may need to use SSH password less login

edited Nov 21, 2014 at 15:35

eush77

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answered May 24, 2011 at 9:45

olragon

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2 Comments

Robin Green Over a year ago

ssh $username@$password $ip $command $arguments won't work (using standard openssh at least) - the password will be interpreted as a hostname, the ip as a command, and the command as the first argument. passwordless login is the way to go.

ychaouche Over a year ago

@RobinGreen But even with passwordless login you still need to type the passphrase to use the private key, no ?

kostix · Accepted Answer · 2011-05-24 14:22:38Z

1

Use sshpass if you really need to use non-interactive keyboard-interactive authentication (pun intended) or better switch to using pubkey-based authentication.

Note that passing the password in clear to the ssh client is very lame as the password gets exposed in the publicly-readable process list where it can be read by anyone. sshpass works around this problem by creating a pseudo-terminal and communicating with the ssh client using it, so at least the password is not exposed at runtime.

answered May 24, 2011 at 14:22

kostix

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Comments

TheAshwaniK · Accepted Answer · 2013-09-16 13:57:55Z

1

Step 1:

jsmith@local-host$ [Note: You are on local-host here]

jsmith@local-host$ ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/home/jsmith/.ssh/id_rsa):[Enter key]
Enter passphrase (empty for no passphrase): [Press enter key]
Enter same passphrase again: [Pess enter key]
Your identification has been saved in /home/jsmith/.ssh/id_rsa.
Your public key has been saved in /home/jsmith/.ssh/id_rsa.pub.
The key fingerprint is:
33:b3:fe:af:95:95:18:11:31:d5:de:96:2f:f2:35:f9 jsmith@local-host

Step 2:
From Local-host, run this One liner for password less ssh connectivity.

cat ~/.ssh/id_dsa.pub | ssh useronanotherserver@anotherservername  'cat >> ~/.ssh/authorized_keys'

answered Sep 16, 2013 at 13:57

TheAshwaniK

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1 Comment

ychaouche Over a year ago

step2 : use ssh-copy-id anotherservername

Community · Accepted Answer · 2017-05-23 12:04:19Z

0

You should use expect, which is an extension of tcl that was made specifically for automating login tasks.

Basic ssh login question: could not able to spawn(ssh) using expect
How to interact with the server programattically after you have established the session: Expect Script to Send Different String Outputs

edited May 23, 2017 at 12:04

CommunityBot

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answered May 24, 2011 at 11:21

Mike Pennington

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4 Comments

Donal Fellows Over a year ago

No! Using passwords like that is significantly less secure than using RSA keys. Of course, once you've done that then you hardly need to use the complexity of expect unless you're automating something nasty on the remote end (which ls definitely isn't…)

Mike Pennington Over a year ago

@Donal, remember that not everyone is a system administrator; automation is often required in lab environments where password security is not relevant. Furthermore some devices (like those running Cisco IOS) cannot use RSA key authentication. This is a simple example meant to illustrate a concept. Add key authentication or whatever you like... then again, I know you are intimately familiar with Tcl, so "you" is whatever reader follows.

Donal Fellows Over a year ago

On most systems, adding an RSA key does not require any system privileges, just placing a public key in the right place (a one-time setup). Given that the result allows an admin to close off all password-based logins (so absolutely defending against distributed cracks) I'm surprised that so many still resist it.

Donal Fellows Over a year ago

Cisco routers though… well, Cisco are a bunch of unhung scum in this respect; they charge a fortune for allowing you to log in securely, as its only supported on their high-end kit. I could rant rather a lot on the topic, but I don't think that really belongs on SO. It's more of a thing for slashdot…

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