Which switch port is that device actually on?
Given a read-only SNMP credential that you supply, LANWRX reads the switch's own forwarding table and tells you which port a device is behind. It never guesses a community string, and it never reports an uplink as if it were the endpoint port.
“Which port is it on” is the question that turns a fifteen-minute job into an afternoon with a tone generator. A managed switch already knows the answer.
How it works
Every managed switch keeps a forwarding database mapping hardware addresses to the port it last saw each one on. LANWRX reads that table over SNMP, joins it to the devices it found in the scan, and shows you the port for each one.
The uplink trap
If a switch is downstream of another switch, every device beyond it appears on the uplink port. A tool that reports that naively tells you forty devices are all on port 24, which is true and useless — and worse, if it picks one it will confidently name the wrong port.
LANWRX counts the addresses on each port. A port carrying many is identified as an uplink or trunk and labelled that way, rather than presented as the answer. Where there is a switch on the other end, it tells you that too.
About credentials
LANWRX asks you for a read-only community string or SNMPv3 credential. It does not trypublic, it does not try private, and it does not work through a list of vendor defaults. Trying credentials until one works is credential guessing; it is what an attacker does, it is logged as such by anything watching, and it is not something a tool on your laptop should do on a client’s network.
The credential you enter goes to Windows Credential Manager, not into the scan database and not into any export.
Read-only, always
What this does not do
- Requires a managed switch with SNMP enabled and a read-only credential that you provide. Unmanaged switches have nothing to ask.
- LANWRX will never try 'public', 'private', or any list of default credentials. Guessing credentials is an attack technique, not a feature.
- LANWRX reads the VLAN-aware forwarding table (Q-BRIDGE) where a switch has one, and falls back to the plain bridge table where it does not. Some older switches expose the table only to a per-VLAN community string — LANWRX does not do community indexing, and says so in the report rather than showing you an empty table.
- A port that carries many hardware addresses is an uplink or a trunk. LANWRX labels it as such rather than naming it as the device's port.
See it on your own network
The free tier covers discovery, identification and the diagnostic tools. No account, no expiry.