Thread by @devops_tech

Mastering SSH🔒!

A Thread explaining 15 most crucial SSH commands 👇

What is SSH!🚀

SSH (Secure Shell) is a secure network protocol that enables users to access & manage remote machines securely over an encrypted connection. It provides a safe & encrypted way to execute commands, transfer files, & perform various tasks on remote servers. #SSH

1/ 🔑To connect to a remote machine, use:

ssh username@remote_host

Replace "username" with your account & "remote_host" with the server's IP/hostname. #SecureConnections #RemoteAccess

2/🗝️ Did you know? You can use SSH keys for authentication, avoiding passwords. Generate your key pair with:

ssh-keygen -t rsa

Then copy your public key to the remote server's ~/.ssh/authorized_keys file.

#KeyAuthentication #SecurityMatters

3/🌐 To execute commands on the remote server, simply:

ssh username@remote_host command

It'll run "command" on the server & show the output locally. Handy, right?

#RemoteCommands #SysAdminLife

4/ 📁 Copying files between local & remote machines? Rely on SCP (SSH Copy):

scp /path/to/local_file username@remote_host:/path/to/destination

Securely transfer files without fuss!

#FileTransfer #SSH

5/🔄 Need to forward ports for secure access to services? Use SSH port forwarding:

ssh -L local_port:destination_host:remote_port username@jump_host

Now access destination_host:remote_port via localhost:local_port.

#PortForwarding #NetworkingTricks

6/⏲️ Running a long task? Prevent disconnection by keeping SSH session alive:

ssh -o ServerAliveInterval=60 username@remote_host

SSH will send a "keep-alive" signal every 60 seconds. No more annoying timeouts!

#StayConnected #ProductivityHacks

7/🚪 Change the default SSH port for added security:

sudo nano /etc/ssh/sshd_config

Modify "Port 22" to a custom port, then restart SSH service. Impenetrable! 🔒

#SecurityFirst #CustomPort

8/ 🚧 Enable X11 forwarding to run GUI applications remotely:

ssh -X username@remote_host

Now, when you run GUI apps, they'll display on your local machine!

#GUIoverSSH #RemoteApps

9/ 🗄️ To securely store passwords, use SSH-agent:

eval "$(ssh-agent)" ssh-add /path/to/private_key

No more entering passwords repeatedly! 🙌

#SSHAgent #PasswordSecurity

10/ 🔒 Disallow root login via SSH to bolster security:

sudo nano /etc/ssh/sshd_config

Set "PermitRootLogin" to "no", then reload SSH. Elevate privileges smartly!

#RootLoginDenied #SecurityTips

11/ 🚪 Limit user access with SSH chroot:

sudo nano /etc/ssh/sshd_config

Use "ChrootDirectory" to restrict users to their home directories. Isolate & control!

#UserIsolation #AccessControl

12/ 🔍 Search remote files like a pro with "grep" over SSH:

ssh username@remote_host "grep -r 'search_term' /path/to/directory"

Search for 'search_term' in files located at '/path/to/directory' on the remote host.

#RemoteSearch #SysAdminTricks

13/ 📜 Edit files on the fly using "sed" over SSH:

ssh username@remote_host "sed -i 's/old_text/new_text/g' /path/to/file"

Replace 'old_text' with 'new_text' in the specified file. Changes applied remotely!

#SSHsed #RemoteEditing

14/ 📊 Monitor resource usage with "top" remotely:

ssh username@remote_host "top"

Get real-time insights into processes, CPU, and memory usage on the remote machine.

#RemoteMonitoring #SysAdminLife

15/ 🔄 Synchronize local and remote directories using "rsync" over SSH:

rsync -avz -e "ssh" /path/to/local_dir username@remote_host:/path/to/destination

Efficiently transfer files between local and remote locations.

#RSync #DataSync

Time for Bonus 💰😍

1/ 🐞 Enable debug mode to troubleshoot SSH connection issues:

ssh -v username@remote_host

Verbose mode displays detailed connection process. Unravel the mysteries!

#SSHDebugMode #Troubleshooting

2/🔐 Authenticate with PEM file (private key) instead of passwords:

ssh -i /path/to/key.pem username@remote_host

Boost security & login with your PEM file. No more passwords! 🚀

#PEMfile #SecureAuthentication

3/ 📁 Copy files using PEM file with SCP:

scp -i /path/to/key.pem /path/to/local_file username@remote_host:/path/to/destination

Combine security & file transfer in one go! 🔒

#SCPPemFile #SecureCopy

4/ 🛡️ Use PEM file with Rsync for secure synchronization:

rsync -avz -e "ssh -i /path/to/key.pem" /path/to/local_dir username@remote_host:/path/to/destination

Safeguard data while syncing directories. 🔐

#RSyncPEM #SecureDataSync

5/🐦💻 SSHAliases: Create aliases for quick access to servers. Edit bash/zsh profile file.

💻 alias server1='ssh user@example[dot]com'
💻 alias server2='ssh user@example[dot]com'

🔒 #Aliases #SSH

6/ 🐦💻SSHFS: Mount remote directories over SSH.
Install 'sshfs' & mount like:

💻 sshfs user@example[dot]com:/remote/path /local/mount/point

7/ 🐦💻SSHKnownHosts: Manage known hosts to prevent man-in-the-middle attacks.

💻nano ~/.ssh/known_hosts

Go forth and master these advanced SSH commands! 💪 Happy remote management!

#SSHAdvanced #SysAdminTools

(Note: Always exercise caution when executing commands that modify or transfer data remotely.)

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