[How-To] SSH

7 thoughts on “[How-To] SSH”

• Olivier says:

  15/02/2019 at 12:16

  Gen SSH keys

  ssh-keygen -t rsa -C "your.email@example.com" -b 4096
  

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• OLIVIER COMBE says:

  03/03/2021 at 11:15

  To enable color over ssh (with or without sshpass) :

  ssh -t toto@VM
  

  or (in case of error like “Pseudo-terminal will not be allocated because stdin is not a terminal”)

  ssh -tt toto@VM
  

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• OLIVIER COMBE says:

  28/04/2021 at 16:01

  SSH without password (using Public/Private key)

  # Generate key
  ssh-keygen -t rsa -b 4096
  
  # Ensure permissions are correct on .ssh folder
  sudo chmod 750 /home/USER
  sudo chown USER:GROUP /home/USER/.ssh
  chmod 0700 ~/.ssh
  chmod 0644 ~/.ssh/known_hosts
  
  # Ensure permissions are correct on authorized_keys and keys
  touch ~/.ssh/authorized_keys
  chmod 0644 ~/.ssh/authorized_keys
  chmod 0600 ~/.ssh/id_rsa
  chmod 0644 ~/.ssh/id_rsa.pub
  
  # Copy Public key to remote target
  ssh-copy-id -i ~/.ssh/id_rsa.pub REMOTE_HOST_IP
  
  
  # Test the connection
  ssh REMOTE_HOST_IP
  

  If the connection is refused, ensure the permissions on .ssh folder is also correct on remote host

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• OLIVIER COMBE says:

  29/04/2021 at 07:17

  SSHD Update config only for a dedicated host :

  # Global settings
  …
  PasswordAuthentication no
  …
  
  # Settings that override the global settings for matching IP addresses only
  Match address 192.0.2.0/24
      PasswordAuthentication yes
  

  systemctl reload sshd
  

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• OLIVIER COMBE says:

  28/05/2021 at 09:30

  Disable HostKey check (CLI) :

  ssh -o StrictHostKeyChecking=no user@server 
  

  Disable UserKnownHostsFile

  ssh -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null user@server 
  

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• OLIVIER COMBE says:

  28/05/2021 at 12:47

  SSH with Identity file and Bastion :

  ~/.ssh/config :

  Host *
    PubkeyAuthentication yes
    StrictHostKeyChecking no
    
  Host SSH_BASTION
    HostName <BASTION_IP>
    IdentityFile /<PATH>/<TO>/bastion.pem
    User userOnBastion
    
  Host *.my-domain-1.com
    IdentityFile /<PATH>/<TO>/my-domain.pem
    ProxyCommand ssh -W %h:%p -qSSH_BASTION
  

  Permissions :
  pemfile : 0600
  config file : 0600
  .ssh folder : 0700

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• OLIVIER COMBE says:

  10/01/2024 at 16:17

  Convert PEM key to PPK key:

  yum install -y putty
  
  puttygen MY_KEY.pem -o MY_KEY.ppk -O private
  

  Convert PPK key to PEM key:

  puttygen MY_KEY.ppk -O private-openssh -o MY_KEY.pem
  

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