Understanding SSH Access

In today’s interconnected world, remote server management is an essential part of system administration. Whether you’re a developer, a system administrator, or a business owner managing a VPS (Virtual Private Server), understanding SSH (Secure Shell) access is crucial for ensuring both security and efficiency.

What is SSH?

SSH (Secure Shell) is a cryptographic network protocol that allows users to securely access and manage a remote computer over an unsecured network.
Instead of sending plain text information like older protocols (e.g., Telnet, FTP), SSH encrypts the session, protecting sensitive information such as usernames, passwords, and commands.

SSH typically runs on port 22, though administrators often change it for security reasons.

How SSH Works

SSH uses a client-server model:

  • The SSH client (your computer) initiates the connection.

  • The SSH server (remote machine) accepts the connection after verifying credentials.

Authentication happens in one of two primary ways:

  • Password-based authentication (you enter a password)

  • Key-based authentication (you use a private/public cryptographic key pair)

Setting Up SSH Access

1. Install an SSH Client
Most Linux and macOS systems come with an SSH client pre-installed.
For Windows, you can use:

  • Windows Terminal (Windows 10+)

  • PuTTY (a popular standalone client)

  • OpenSSH for Windows (optional feature)

2. Connect to a Server
Use the basic SSH command:

ssh username@server_ip_address

Example:

ssh admin@192.168.1.10

3. Accept the Host Key
The first time you connect, the client will ask you to verify the server’s host key for security.

4. Authenticate

  • With a password, you’ll be prompted to enter it.

  • With a private key, SSH uses the key automatically or you specify it:

    ssh -i /path/to/privatekey.pem username@server_ip_address

 SSH Security Best Practices

  1. Disable Password Login
    Switch to key-based authentication only. It’s far harder to brute-force a cryptographic key than a password.

  2. Change Default SSH Port
    Changing from port 22 to another random port reduces automatic scanning attempts.

  3. Use Strong, Unique SSH Keys
    Generate keys with at least 2048-bit encryption (ssh-keygen -t rsa -b 4096).

  4. Limit SSH Access by IP Address
    Configure firewall rules to allow SSH access only from trusted IPs.

  5. Enable Two-Factor Authentication (2FA)
    Some SSH servers support 2FA for even stronger authentication.

  6. Keep Software Updated
    Always patch your SSH server software to protect against vulnerabilities.

  7. Use Fail2Ban or Similar Tools
    Install tools that automatically ban IPs attempting brute-force attacks.

Useful SSH Commands for Management

  • Copy files between local and remote:

    scp localfile.txt username@server_ip:/remote/directory/

  • Open an interactive file editor (like nano, vim, or vi) to modify server files.

  • Manage services (on Linux servers):

    sudo systemctl restart apache2
    sudo systemctl status nginx

  • Monitor server activity:

    top
    htop

  • Exit the SSH session:

    exit

SSH is a foundational tool for modern server administration, enabling secure, encrypted management of remote systems.
By understanding how SSH works and following security best practices, you can manage your servers confidently, protect critical data, and ensure operational stability.

Whether you’re managing a small personal project or a large enterprise infrastructure, SSH knowledge is essential for every IT professional.