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Linux Remote Shell Notes

2,074 bytes removed, 21:29, 24 July 2020
/* auto login ssh */
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Secure Shell (SSH) and Telnet are the two most common remote management protocols.  The configuration of Telnet is a common practice, but it is advisable to use SSH. The reason for this is that Telnet data is sent in plain text in contrast to SSH, which encrypts the data.  Tools like wireshark and snort can be used to intercept unencrypted data over a LAN or extra network connection.   [[Secure Shell]] (SSH) and Telnet are the two most common remote management protocols.  The configuration of Telnet is a common practice, but it is advisable to use SSH. The reason for this is that Telnet data is sent in plain text in contrast to SSH, which encrypts the data.  Tools like wireshark and snort can be used to intercept unencrypted data over a LAN or extra network connection.   == ssh - The Secure Shell ==== ssh - The [[Secure Shell]] ===== Secure Shell Support for Remote Login ====== [[Secure Shell]] Support for Remote Login ===You'll need to be able to ssh with automated password or enter the password each time you run the command.{{:Secure Shell - use SSH to execute a remote command}} Execute a remote command on a host over SSH: ssh nicolep@192.168.100.10 'reboot'The example above will reboot the remote computer. Multiple commands ssh nicolep@192.168.100.10 'uptime; df -h' Show the kernel version, number of CPUs and the total RAM: ssh root@192.168.100.10 << EOF uname -a lscpu  | grep "^CPU(s)" grep -i memtotal /proc/meminfo EOF Here is how Nicole can execute her script on the remote computer ssh nicolep@192.168.100.10 'bash -s' < nicolejob.shNicole's script is local on her machine, and she executed it on the remote host. {{:Secure Shell - auto login ssh}}The OpenSSH ssh utility doesn't accept a password on the command line or on its standard input.  The nanny mentality whereby the developer protects us from ourselves by preventing us from doing something that compromises security, even though the result may be worse. OPTIONS FOR SSH AUTOMATED# Use an SSH key for authentication, instead of a password.# Use sshpass, expect, or a similar tool to automate responding to the password prompt.# Use the SSH_ASKPASS feature to get ssh to get the password by running another program.# Use the insecure host-based authentication, sometimes common on private networks.# Use a custom or modified ssh client adapted from source code, or one that allows for stored password. === sshpass ===Install the sshpass utility so that you can automate ssh login including password. apt install sshpassNow you can automate the login process sshpass -p "mysecretpass" ssh -o StrictHostKeyChecking=no nicolep@192.168.100.10Custom port example: sshpass -p "mysecretpass" ssh -o StrictHostKeyChecking=no nicolep@192.168.100.10:9600 === public key authentication ===In the source host run this only once: ssh-keygen -t rsa Now you've generated the public key.  It needs to be copied onto the remote host.  ssh-copy-id -i ~/.ssh/id_rsa.pub nicolep@192.168.100.10add identities to the ssh-agent – the authentication agent on the local host. ssh-addnow press ENTER to every field ssh-copy-id nicolep@192.168.100.10 === expect ===Example script #!/usr/bin/expect set timeout 15 set cmd [lrange $argv 1 end] set password [lindex $argv 0] eval spawn $cmd expect "assword:" send "$password\r"; interact Another example #!/usr/bin/expect -f #  ./ssh.exp password 192.168.100.10 id set pass [lrange $argv 0 0] set server [lrange $argv 1 1] set name [lrange $argv 2 2] spawn ssh $name@$server match_max 100000 expect "*?assword:*" send -- "$pass\r" send -- "\r" interact And finally, a more elaborate example can be found here:* http://www.techpaste.com/2016/02/ssh-login-with-password/== login and non-login shell ==The .bash_profile is executed for login shells, while .bashrc is executed for interactive non-login shells.When you login (type username and password) via console, either sitting at the machine, or remotely via ssh: .bash_profile is executed prior to the initial command prompt.When you are logged into your machine already and open xterm in your desktop environment then .bashrc is executed prior to seeing a prompt.  The .bashrc is also run when you start a new bash instance by typing /bin/bash in a terminal.
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