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Glossary

A comprehensive guide to terms and concepts used in Xermius.

Core Concepts​

Host​

A Host represents a remote machine (server) you want to connect to via SSH. Each host contains:

  • Connection details (IP, port, username)
  • Authentication method (password or SSH key)
  • Metadata (name, tags, group)
  • Multiple protocol configurations (SSH, SFTP, etc.)

Example:

{
  "name": "Production Web Server",
  "host": "192.168.1.100",
  "port": 22,
  "username": "ubuntu",
  "group": "Production"
}

Group​

A Group is a collection of hosts that share something in common (customer, location, environment, etc.). Groups can be nested to create hierarchies.

Example Structure:

📁 Servers
├── 📁 Production
│   ├── 🖥️ Web Server 1
│   └── 🖥️ Database Server
└── 📁 Development
    └── 🖥️ Dev Server

Connection​

A Connection is an active SSH session to a host. In Xermius:

  • Each terminal tab creates a new connection
  • SFTP tabs use separate connections
  • Multiple connections to the same host can exist simultaneously

Connection Types:

  • Original Connection: The base host configuration stored in database
  • Tab Connection: A temporary session for a specific tab (not stored in database)

Session​

A Session refers to the active state of a connection, including:

  • SSH client instance
  • Terminal state
  • Authentication status
  • Keep-alive settings

SSH Terminology​

SSH (Secure Shell)​

A cryptographic network protocol for secure remote access to computers.

Key Components:

  • SSH Client: Your computer (running Xermius)
  • SSH Server: The remote machine you connect to
  • SSH Port: Usually 22, but can be customized

SFTP (SSH File Transfer Protocol)​

A secure file transfer protocol built on top of SSH, providing:

  • File upload/download
  • Directory navigation
  • Permission management
  • File operations (rename, delete, create)

SSH Key​

An authentication credential for SSH protocol, consisting of:

  • Private Key: Kept secret on your computer
  • Public Key: Installed on the server

Common formats:

  • RSA (older, still widely used)
  • ED25519 (modern, recommended)
  • ECDSA (Elliptic Curve)

Host Key​

A cryptographic key that identifies an SSH server. Used to prevent man-in-the-middle attacks.

Host Key Fingerprint: A hash of the host key, easier to verify:

SHA256:abc123...xyz789

Known Hosts​

A file (~/.ssh/known_hosts) containing fingerprints of servers you've connected to before. Xermius manages this automatically.

Authentication​

Password Authentication​

Traditional method using username and password to authenticate.

Pros: Simple, no setup required
Cons: Less secure, vulnerable to brute force

SSH Key Authentication​

Uses public/private key pairs for authentication.

Pros: More secure, no password needed
Cons: Requires initial setup

Passphrase​

An optional password that encrypts your private key file.

Example:

Private Key: /home/user/.ssh/id_rsa
Passphrase: MySecretPassphrase123

Two-Factor Authentication (2FA)​

Additional security layer requiring:

  1. Something you know (password)
  2. Something you have (authenticator app code)

Port Forwarding​

Tunnel​

A secure encrypted connection that forwards network traffic through SSH.

Local Port Forwarding (-L)​

Forwards a local port on your machine to a remote host.

Use Case: Access a service on the server from your local machine.

Example:

Local Port: 3306 → Remote: localhost:3306
Connect to: localhost:3306 (on your machine)
Result: Access MySQL on remote server

Remote Port Forwarding (-R)​

Forwards a remote port on the server to your local machine.

Use Case: Expose a local service to the remote server.

Example:

Remote Port: 8080 → Local: localhost:3000
Result: Server can access your local app on port 8080

Dynamic Port Forwarding (-D)​

Creates a SOCKS5 proxy server on your local machine.

Use Case: Route all traffic through SSH tunnel (like a VPN).

Example:

Local Port: 1080 (SOCKS5 proxy)
Configure browser to use: localhost:1080
Result: Browse web through SSH tunnel

SOCKS5​

A proxy protocol that supports any type of internet traffic.

Synchronization​

Sync​

The process of keeping your hosts, settings, and configurations synchronized across multiple devices.

What's Synced:

  • ✅ Hosts and groups
  • ✅ Connection settings
  • ✅ Port forwarding rules
  • ✅ SSH keys (encrypted)

What's NOT Synced:

  • ❌ Passwords (stored locally only)
  • ❌ Active sessions
  • ❌ Terminal history

Backend / Cloud​

The Xermius server that stores your synced data securely.

Encryption Key​

A key used to encrypt sensitive data (passwords, SSH keys) before storage.

Security:

  • Generated locally on your device
  • Never sent to the server
  • Required to decrypt data

User Interface​

Dashboard​

The main screen showing all your hosts, groups, and quick actions.

Tab​

A container for terminal or SFTP sessions. Multiple tabs can be open simultaneously.

Tab Types:

  • Terminal Tab: SSH terminal session
  • SFTP Tab: File manager interface
  • Web Tool Tab: SSL checker, cert reader, etc.

The left panel containing navigation and groups.

Status Bar​

The bottom bar showing connection status, network stats, etc.

Import/Export​

Import​

The process of bringing host configurations from other SSH clients into Xermius.

Supported Sources:

  • SSH Config files
  • CSV files
  • PuTTY sessions
  • MobaXterm bookmarks
  • SecureCRT sessions

Export​

The process of saving Xermius hosts to external formats.

Supported Formats:

  • SSH Config
  • CSV
  • JSON

Migration​

Moving all your data from another SSH client to Xermius.

Web Platform​

Account​

Your Xermius user account for accessing the web platform and sync features.

Subscription​

Xermius offers two plans:

Plans:

  • Freemium (Free): Essential features for personal use
  • Pro: Advanced features with cloud sync and priority support

Device​

A computer or device logged into your Xermius account.

Device Management:

  • View all devices
  • Rename devices
  • Revoke access

Activity Log​

A record of all actions performed on your account:

  • Logins
  • Settings changes
  • Host modifications
  • Sync events

Support Ticket​

A request for help sent to the Xermius support team.

Ticket Properties:

  • Subject
  • Category (Technical, Billing, etc.)
  • Priority (Low, Medium, High, Urgent)
  • Status (Open, In Progress, Closed)

Technical Terms​

API (Application Programming Interface)​

Secure communication interface that handles authentication, sync, and account management.

WebSocket​

Real-time communication protocol used for:

  • Support ticket updates
  • Sync notifications
  • Activity logging

Encryption​

The process of converting data into a secure format.

Methods used:

  • AES-256: Symmetric encryption for data at rest
  • RSA-2048: Asymmetric encryption for key exchange
  • TLS/SSL: Transport encryption for network traffic

File Formats​

PEM (Privacy Enhanced Mail)​

A format for storing cryptographic keys and certificates.

Extensions:

  • .pem: Generic PEM file
  • .key: Private key
  • .pub: Public key
  • .crt: Certificate

OpenSSH Format​

The default format for SSH keys used by OpenSSH.

Example:

-----BEGIN OPENSSH PRIVATE KEY-----
b3BlbnNzaC1rZXktdjEAAAAABG5vbmUAAAAEbm9uZQA...
-----END OPENSSH PRIVATE KEY-----

PuTTY Private Key (PPK)​

PuTTY's proprietary format for private keys.

Conversion: Xermius can import PPK files and convert them to OpenSSH format.

Protocols​

SSH Protocol Versions​

  • SSH-1: Obsolete, insecure
  • SSH-2: Current standard (Xermius uses this)

Port Numbers​

  • 22: Default SSH port
  • 2222: Common alternate SSH port
  • 1080: Common SOCKS5 proxy port

IP Addressing​

  • IPv4: 192.168.1.100 (standard)
  • IPv6: 2001:db8::1 (supported)
  • Hostname: server.example.com (DNS name)

Error Messages​

Connection Timeout​

Server didn't respond within the timeout period.

Common Causes:

  • Firewall blocking connection
  • Server is down
  • Wrong IP address
  • Network issues

Connection Refused​

Server rejected the connection.

Common Causes:

  • SSH service not running
  • Wrong port number
  • Firewall blocking port

Authentication Failed​

Credentials were rejected by the server.

Common Causes:

  • Wrong username or password
  • Key file not authorized
  • Key file permissions too open (should be 600)

Host Key Verification Failed​

The server's host key doesn't match the known key.

Possible Reasons:

  • Server was reinstalled
  • Server IP changed
  • Man-in-the-middle attack

Abbreviations​

  • CLI: Command Line Interface
  • GUI: Graphical User Interface
  • PTY: Pseudo Terminal
  • TTY: Teletypewriter (terminal)
  • VPS: Virtual Private Server
  • VM: Virtual Machine
  • EC2: Amazon Elastic Compute Cloud
  • GCP: Google Cloud Platform
  • AWS: Amazon Web Services
  • DO: DigitalOcean

See Also​