SSH

The SSH protocol

The SSH protocol uses encryption to secure the connection between a client and a server. All user authentication, commands, output, and file transfers are encrypted to protect against attacks in the network.

SSH Commands

Command	Desc
ssh {user}@{serverip}	access remote server
ls	Show directory contents (list the names of files).
cd	Change Directory.
mkdir	Create a new folder (directory).
touch	Create a new file.
rm	Remove a file.
cat	Show contents of a file.
pwd	Show current directory (full path to where you are right now).
cp	Copy file/folder.
mv	Move file/folder.
grep	Search for a specific phrase in file/lines.
find	Search files and directories.
vi/nano	Text editors.
history	Show last 50 used commands.
clear	Clear the terminal screen.
tar	Create & Unpack compressed archives.
wget	Download files from the internet.
du	Get file size.

Other commands / resources

• apt-get
• rsync
• Digital Ocean

SSH vs SSL/TLS – What are Differences and Similarities?

SSH and SSL/TLS generally have different purposes. SSH is often used by network administrators for tasks that a normal internet user would never have to deal with. SSL/TLS, on the other hand, is used by the average internet user all the time. Any time someone uses a website with a URL that starts with HTTPS, he is on a site with SSL/TLS.

	SSH	SSL/TLS
Abbreviation	Secure Shell	Secure Socket Layer/Transport Socket Layer
Port	SSH runs on port 22	SSL runs on port 443
Usage	For securely executing commands on a server.	For securely communicating personal information.
Application	For encrypting communication between two computers (host & client).	For encrypting communication between browser and server
	It is used to reduce security threats for remote server login	It allows secure transition of data between a server and the browser thus, keeps information intact.
Adopted by industry	Widely adopted by networking industry	Widely used by e-commerce, banking, social media, government, healthcare, etc.
Authentication	Via 1. public-key / private-key pair or 2. user-id / password pair	Via public-key / private-key pair
	a username/password authentication system to establish a secure connection.	Normally uses X.509 digital certificates for server and client authentication.
	SSH is working based on network tunnels.	SSL is working based on digital certificates.
	SSH follows authentication process by server’s verification done by client, session key generation, and client’s authentication	SSL follows authentication process by exchange of digital certificate
Protocol	SSH is a remote protocol	SSL is a security protocol
Data integrity	Measured with algorithms like SHA, SHA-2, SHA-256	Measured with the message digest and added to encrypted data before the data is sent.