NetDisco — When the Network Map Needs to Match Reality
Keeping track of what’s plugged in where — and how it got there — is a bigger problem than most want to admit. Spreadsheets drift, devices move, VLANs shift, and suddenly no one knows what port that mystery printer is on. NetDisco was built for that exact mess.
It’s a web-based Layer 2/3 network discovery tool that walks the switches, collects ARP and MAC tables, and builds a live map of everything wired. No agents. No guesswork. Just SNMP, CDP/LLDP, and raw topology data — stitched together into something actually usable.
What It Brings to the Table
| Feature | Practical Use |
| Switch and Port Inventory | Automatically detects what’s connected to each port on each switch. |
| MAC and IP Correlation | Links IPs to MACs to physical interfaces — great for tracing rogue devices. |
| SNMP-Based Discovery | Uses standard MIBs — no vendor lock-in, works across mixed environments. |
| Web Interface | Everything accessible from the browser — no fat client needed. |
| Search by Anything | IP, MAC, hostname, switch port — if it’s in the network, it’s findable. |
| Passive Operation | Doesn’t scan — just watches, queries, and builds context. |
| VLAN Awareness | Maps per-VLAN topologies and device visibility. |
| Scheduled Polling | Keeps maps and tables updated on a defined cycle. |
Where It Fits Naturally
NetDisco isn’t for packet analysis. It doesn’t capture flows or dig into payloads. What it does is show who’s plugged in, where they are, and how they got there — in real time.
It’s ideal in:
– Campus networks where devices shift often and documentation never keeps up.
– Environments with lots of dumb switches and no central visibility.
– Mixed-vendor networks where SNMP is the only common language.
– Audit-heavy industries that need physical traceability of devices.
– Troubleshooting scenarios where “someone unplugged something” isn’t a joke.
Deployment Basics (Old School, but Solid)
- Install the Core Stack
NetDisco is built on Perl with a PostgreSQL backend. Most distros have packages or instructions. It’s old-school, but well-documented.2. Enable SNMP on Switches
Community strings, access lists — make sure the monitoring box can talk to the gear.3. Seed the Topology
Add a list of switch IPs or let NetDisco crawl from a known entry point.4. Fire Up the Web UI
Runs on a local web port. Login, explore, search, export. It’s not flashy, but it works.5. Schedule Polling
Use the built-in daemon or system scheduler to keep discovery fresh.6. Trace Anything
Need to find which port a MAC is on? Two clicks. Need to trace it across VLANs? It’s already there.
Final Thoughts
NetDisco isn’t new, and that’s part of the appeal. It solves a real problem — network visibility at the cable level — with no vendor lock-in, no subscriptions, and no unrealistic promises.
When other tools are trying to do everything, NetDisco focuses on one job and does it right: showing what’s really on the network — not what’s supposed to be.
