What Is a Collector?

A collector is a small, lightweight agent you run inside your network. It’s how GridNMS actually sees your equipment. Every GridNMS deployment — cloud or self-hosted — uses at least one.

What a collector does

• Checks reachability — pings your devices to track up/down status.
• Polls for metrics — gathers interface traffic, CPU, memory, disk, and more from your devices using the credentials you provide.
• Receives logs and traps — listens for syslog and SNMP traps sent by your devices.
• Runs discovery scans — finds new devices on the ranges you assign.

It then sends all of this back to GridNMS over secure outbound connections, all on standard HTTPS (443).

Why outbound-only matters

You never have to open inbound firewall ports to GridNMS. The collector always makes the connection out to your GridNMS instance, which is simpler and safer — especially across sites and through NAT. See Installing a Collector → Ports & firewall for exactly what to allow if your firewall doesn’t permit all outbound HTTPS.

   Your site                              GridNMS
 ┌─────────────────────┐               ┌──────────────┐
 │ switches / routers  │               │              │
 │ firewalls / servers │──► collector ─┼──► web app   │
 │ syslog + SNMP traps │   outbound,   │   dashboards │
 └─────────────────────┘   encrypted   └──────────────┘

How many collectors do I need?

Run one collector per site or network segment. A single collector can watch many devices across the networks you assign to it, so a small office needs just one. Add more for:

• Additional physical sites — one collector per location.
• Isolated network segments — when a single collector can’t route to every subnet.
• Scale and resilience — spread load across several collectors.

Your setup	Collectors
One office	1
Headquarters + 3 branches	4 (one each)
Self-hosted, single site	1 (installed the same way as any other collector)
Self-hosted, multi-site	1 per site

What a collector is allowed to reach

A collector only talks to the networks you assign to it (plus your GridNMS instance). This assignment is the boundary that controls what it can scan and monitor — see Networks & Sites.

Keeping collectors updated

A collector doesn’t update itself in place. To move one to a newer version, download the newer build from the Customer Portal → Downloads and re-run the installer on that host — it’s safe to run on an already-installed collector and won’t lose its enrollment. See Installing a Collector → Updating.

Next steps

• Installing a Collector — set one up on Linux or macOS.
• Collector Services — every service starts off; what each one does and how to turn it on.
• Getting the Real Source IP — essential reading before you send syslog.
• Networks & Sites — assign what each collector watches.
• Collector Profiles — control which collector actively polls a device when more than one covers it.
• Log Routing — ship a collector’s logs to GridNMS, or keep them on your own network.