Network Discovery uses a combination of active and passive technologies to detect connected assets and gather available data. Using multiple methods increases the likelihood of retrieving asset details. Even if one method fails, another may succeed.
Some protocols require the target device to support the technology and allow communication through specific ports.
The tables below outline the protocols used by Network Discovery and their associated ports.
Active detection protocols
| Protocol | Port | Description |
|---|---|---|
| ARP (Address Resolution Protocol) | None | Maps IP addresses to physical devices. Operates below TCP and is not blocked by firewalls. |
Active interrogation protocols
Default protocols
| Protocol | Port | Description |
|---|---|---|
| ICMP (Internet Control Message Protocol) | None | Uses echo requests (PING) to identify devices and infer OS from TTL values. May be blocked by firewalls unless explicitly allowed. |
| DNS (Domain Name Service) | UDP 53 | Resolves hostnames from IP addresses. |
| SMB (Server Message Block) | TCP 445 | Retrieves host name, domain, and OS version. Commonly used for Windows file sharing. |
| NetBIOS | UDP 137, 138 | Provides name services for Windows and SMB-enabled non-Windows devices. |
| mDNS (Bonjour) | UDP 5353 | Allows devices to advertise services on the local subnet. Requires multicast to be enabled. |
| TCP port scanning | Various | Identifies available services to help determine device type. |
Custom protocols
Configured in the Managed Network dialog
| Protocol | Port | Description |
|---|---|---|
| SNMP (Simple Network Management Protocol) | UDP 161 | Queries SNMP-enabled devices using a community string. Returns device name and description. Supports SNMPv1. |
| WMI (Windows Management Instrumentation) | TCP 135TCP 1024–65535 (Windows 2003)TCP 49152–65535 (Windows 2008+) | Provides detailed scan data for Windows devices. Enabled by default on Active Directory domains. Requires firewall access. |
| Telnet | TCP 23 | Allows remote shell access to run commands. Unencrypted. |
| SSH (Secure Shell) | TCP 22 | Secure remote shell access. Encrypted with SSL. |
| HTTP/HTTPS | TCP 80/443 | Retrieves data from web configuration interfaces (e.g. routers, servers, printers, NAS). |
Related articles