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Glossary

Definitions of technical terms used throughout the Campus WoL documentation. Each heading links directly -- use the anchor in the URL to reference a specific term (for example, glossary.md#magic-packet).

ARP

Address Resolution Protocol -- how devices on a network find each other's hardware addresses. When one device wants to communicate with another on the same local network, it broadcasts an ARP request asking "who has this IP address?" The device with that IP responds with its MAC address.

Campus WoL uses ARP to verify whether a device is online after sending a magic packet. If the device responds to an ARP query, it has successfully woken up.

Audit Log

A record of every action taken in the system. Each entry includes who performed the action, what they did, when it happened, and from which IP address. Audit logs are append-only -- entries cannot be edited or deleted through the application.

Administrators use the audit log for accountability, compliance, and troubleshooting. Only users with the Admin role can view audit log entries.

Cron Expression

A schedule format using five fields to define when automated jobs run. The five fields are, in order: minute, hour, day of month, month, and day of week.

For example, 0 7 * * 1-5 means "at 7:00 AM on every weekday (Monday through Friday)." The asterisk (*) means "every possible value" for that field.

Campus WoL uses cron expressions to define when scheduled wake operations and scans run automatically.

JWT

JSON Web Token -- a secure session token issued after you log in. Instead of requiring you to send your password with every request, the system gives you a JWT that proves your identity. The server verifies the token's signature on each request to confirm it has not been tampered with.

By default, JWTs in Campus WoL expire after 120 minutes. After expiration, you will need to log in again to receive a new token.

MAC Address

Media Access Control Address -- a unique hardware identifier assigned to every network interface, formatted as six pairs of hexadecimal characters separated by colons (for example, AA:BB:CC:DD:EE:FF). Unlike IP addresses, which can change, MAC addresses are permanently assigned to the hardware by the manufacturer.

Campus WoL uses MAC addresses to target specific devices for wake operations. The magic packet contains the target device's MAC address, and only the matching network interface will respond to it.

Magic Packet

A special network message that tells a powered-off device to turn on. The packet consists of six bytes of FF followed by the target device's MAC address repeated 16 times. When a network interface card that has Wake-on-LAN enabled detects this pattern, it signals the motherboard to power on.

Magic packets are the core mechanism behind Wake-on-LAN. They are sent as broadcast frames, meaning every device on the network segment receives them, but only the device whose MAC address matches will act on the packet.

OUI

Organizationally Unique Identifier -- the first three bytes of a MAC address, which identify the device's manufacturer. For example, a MAC address starting with 00:1A:2B might belong to a Dell network interface.

Campus WoL performs OUI lookups when displaying discovery scan results, showing the manufacturer name alongside each discovered device. This helps administrators identify devices without needing to check each one physically.

RBAC

Role-Based Access Control -- a security model where permissions are assigned to roles rather than to individual users. Instead of configuring access for each person separately, you assign users to a role, and the role determines what they can do.

Campus WoL uses three roles:

  • Viewer -- can see device status and wake history, but cannot trigger operations or change settings.
  • Operator -- can perform wake operations and run scans, in addition to everything a Viewer can do.
  • Admin -- has full access, including user management, site configuration, and audit log viewing.

SNMP

Simple Network Management Protocol -- a standard protocol for querying and managing network devices like switches, routers, and access points. Network devices that support SNMP expose information about their status, configuration, and connected clients.

Campus WoL's optional snmp-agent can poll switches using SNMP to build a map of which devices are connected to which switch ports. This feature is useful for tracking physical network topology but is not required for basic wake operations.

VLAN

Virtual LAN -- a way to divide a single physical network into multiple separate logical networks. Devices on the same VLAN can communicate with each other as if they were on the same physical network, even if they are connected to different switches.

In Campus WoL, each classroom is assigned to a VLAN. This determines which network segment the classroom's devices are on and ensures that magic packets are sent to the correct network segment.

Wake-on-LAN (WoL)

A networking standard that allows a device to be powered on remotely by sending a magic packet to its MAC address. For WoL to work, three things must be true:

  1. The device's network interface card must support Wake-on-LAN.
  2. WoL must be enabled in the device's BIOS/UEFI firmware settings.
  3. The device must be connected to power and to the network.

When all three conditions are met, the network interface card maintains a low-power listening state even when the computer is off, waiting for a magic packet addressed to its MAC address.

Unix Socket

A local communication channel between programs running on the same machine. Unlike network connections that send data over a network (and could potentially be intercepted), Unix sockets exist only as files on the local filesystem. Data sent through a Unix socket never leaves the machine.

Campus WoL uses Unix sockets for communication between its backend API server and its network agents (wol-agent, scan-agent, snmp-agent). This design ensures that the control channel between the backend and agents is not exposed to the network.