SSH Automatic/Passwordless Logon - Setup Public Key Encryption In Single Command

This is a very simple solution, but most guides out there make you login twice (once to scp the key) and once to put the key in authorized_keys.  There\'s no need for that. 

If you don\'t already have a ~/.ssh/id_rsa.pub just type "ssh-keygen -t rsa" and keep hitting enter until it\'s done :)

Just use this code to easily enable passwordless login with SSHD

key=`cat ~/.ssh/id_rsa.pub`;ssh user@192.168.5.25 "echo $key >> ~/.ssh/authorized_keys"

Copy and paste the above into your shell, just be sure to change the "user@" portion to the correct user and the 192.168.5.25 to the server that you want to login without any password authentication.

Also be very sure to keep the backticks and the double quotes ", otherwise you\'ll find it won\'t work properly and tha tthe "~" will expand to the relative path on your current host, which is not what we want.  The double quotes force the shell to pass the command as it should be to the target host.

An Even Better Way (just copy the below it prompts you for the login info so there\'s no need to hand edit anything.

echo "Enter Target Info (eg. root@192.168.1.25";read ipaddress;key=`cat ~/.ssh/id_rsa.pub`;ssh $ipaddress "mkdir ~/.ssh;echo $key >> ~/.ssh/authorized_keys"

Here is a handy bash script for automatic SSH Login/Keyexchange

I just prompts for the login details eg. root@192.168.5.25 and then all you have to do is enter your password and the next time you try to login it will be automatic.  Remember to run "ssh-keygen -t rsa" if you haven\'t created your public/private keys in .ssh yet.

#!/bin/bash
#(c) 2016 - realtechtalk.com
#free to distribute by keeping above credit
echo "Enter the Host: username@ipaddress"
read ipaddress
echo "Setting Up Key Exchange with: \"$ipaddress\""
key=`cat ~/.ssh/id_rsa.pub`
target=$ipaddress
ssh "$target" "mkdir -p ~/.ssh;echo $key >> ~/.ssh/authorized_keys;echo 0 > /selinux/enforce;sed -i 's/SELINUX=enforcing/SELINUX=disabled/g' /etc/selinux/config"
#(c) 2010 - realtechtalk.com
#free to distribute by keeping above credit

*Disable SELinux or you can\'t login automatically on Centos 6.x

#!/bin/bash

#disable SELinux Immediately
echo 0 > /selinux/enforce

#disable SELinux Permanently
sed -i \'s/SELINUX=enforcing/SELINUX=disabled/g\' /etc/selinux/config
 


Tags:

ssh, passwordless, logon, encryption, commandthis, guides, login, scp, authorized_keys, id_rsa, pub, quot, keygen, rsa, enable, sshd, user, echo, shell, portion, server, password, authentication, backticks, quotes, ll, tha, tthe, expand, relative, prompts, info, edit, eg, ipaddress, mkdir, bash, keyexchange, haven, bin, realtechtalk, distribute, username, selinux, enforce, sed, enforcing, disabled, etc, config, disable, automatically, centos, permanently,

Latest Articles

  • Linux ln symlink how to update existing symbolic link
  • Ubuntu 18.04 / Linux Mint 19.1 Cannot Type or Login - solution
  • LUKS Hard Drive Encryption on Linux Mint Ubuntu Debian etc how to mount encrypted hard drive
  • How to use nmap locate other machines/computers/servers on your network using nmap
  • Linux Mint 18.2 Create Config File To Start Application Upon Login
  • Dell Wyse Thin Client BIOS Access Key
  • sudoers file in /etc warning about comments/includes!
  • Centos 7 Reallocate logical volume space to another
  • lvm how to reduce volume size
  • letsencrypt certbot error "Unable to find a virtual host listening on port 80 which is currently needed for Certbot to prove to the CA that you control your domain. Please add a virtual host for port 80."
  • SSH error cannot Forward or Listen "bind: Cannot assign requested address"
  • X11 SSH Linux Forwarding Error
  • Using Microsoft's Group Policy Management Editor (GPME) To Change Default Permissions and Internet Explorer Security Settings
  • Thunderbird How To Disable An Email Account
  • iptables linux firewall recommended rules for public computing
  • LVM How To Create Pool (dynamically allocated and not fully allocated)
  • VMWare Pro Workstation Nic Disconnected and No IP Using NAT
  • Linux How To Create A RamDisk
  • mdadm force resync when resync=PENDING solution
  • Proxmox Breaks Storage/LVM Backing If Killing QEMU-IMG