SSH Protocol and ssh/scp Commands

Linux Tutorials - Herong's Tutorial Examples

∟SSH Protocol and ssh/scp Commands

This chapter provides introductions and tutorial notes on SSH (Secure SHell) protocol and 'ssh/scp' commands. Topics include SSH connection steps; user password and public key authentication methods; SSH server configuration settings; 'ssh' for remote login sessions; 'scp' for copying remote files.

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SSH (Secure SHell) Protocol

How Does SSH Work

SSH Connection Example - "ssh" Remote Terminal Session

SSH Server Verification with Server Public Key

Set Up User Public Key Authentication

SSH Server Configuration

"ssh" - SSH Client for Remote Login

"scp" - Secure Copy Remote Files

"ssh -vvv" - Very Very Verbose Mode

SSH "debug2: we did not send a packet, disable method"

Takeaways:

SSH is a communication protocol based on TCP/IP to a secure transport layer and multiple logical communication channels.
SSH client uses server public key to verify server's identity.
SSH server can use user password to authenticate client user.
SSH server can use user public key to authenticate client user.
SSH server offers flexible configurations with user and IP address level override rules.
"ssh" is a SSH client command for secure remote login, replacing "telnet".
"scp" is a SSH client command for copying files from and to SSH server, replacing "ftp".
"ssh -vvv" turns on the very very verbose mode to generate debugging messages.
/var/log/security log file on the SSH server is very helpfull for resolving SSH connection issues.