LinkSight

LinkSight is a desktop readout for the moment you plug into a strange port: what am I attached to, and where does it go?

It listens passively on the wire for LLDP, CDP, and DHCP traffic and reports the neighbouring switch, the port ID and description, the VLAN, and the management addresses — all in memory, with no historical log and no active scanning.

Download

Windows, macOS, and Linux builds are attached to the latest release. No account, no email gate, no installer required.

LinkSight-Portable.exeWindows · single self-contained executable · ~51 MB · decompresses to a temp directory on each run

LinkSight-windows.zipWindows · portable folder build · ~55 MB · extracts once at build time, so startup is instant

LinkSight-mac.zipmacOS · application bundle · ~110 MB

All releases and checksums →

Install

Windows

1. Download LinkSight-windows.zip (or LinkSight-Portable.exe for a single file to copy to a jump host).
2. Install the Npcap driver from npcap.com if it is not already present. Packet capture does not work without it.
3. Run LinkSight.exe as Administrator. Raw capture requires elevation.

macOS

1. Download LinkSight-mac.zip and unzip it.
2. Move LinkSight.app to Applications.
3. Grant packet capture access when prompted — BPF device access needs admin rights, and macOS may ask for terminal permission the first run.

From source (any platform)

python -m venv .venv
source .venv/bin/activate        # Windows: .venv\Scripts\activate
pip install -r requirements.txt
python app.py                    # capture starts automatically
python app.py --demo             # replay simulated frames, no capture privileges needed

On Linux, capture needs CAP_NET_RAW — run via sudo, or grant the capability to the binary.

What it reads

Panel	Contents
NIC status	Local adapters with link status, IP, MAC, and hardware description
LAN info	IP, subnet mask, gateway, DNS servers, DHCP server and lease details
Switch info	Neighbouring device hostname, model, port ID, port description, VLAN ID, management IPs

Management IPs are clickable: LinkSight prompts for a username and opens a system terminal with ssh username@ip. Passwords are typed into the ssh prompt — LinkSight never captures or stores credentials.

There is also a Raw frames toggle that expands a live hexdump of captured LLDP, CDP, and DHCP frames, so a result can be checked against Wireshark.

Upstream discovery

Upstream discovery walks the physical switch chain from the port you are attached to, up to the edge — core switch, spanning-tree root, or the router or firewall that faces the WAN.

• Hop cards show the traced path ports — downlink to the previous hop, uplink to the next — with per-port diagnostics behind an expander: PVID, tagged and untagged VLAN semantics, allowed VLANs, spanning-tree state, link speed, and neighbour identity.
• The walk follows each switch’s spanning-tree root port, so it does not recurse into downstream IDF switches, and stops cleanly at the root bridge or the edge device.
• At the firewall it queries the interface table and the default route to identify the active WAN interface, its negotiated speed, operational status, and the upstream gateway.
• Where a switch does not expose spanning-tree MIBs (UniFi, for example), discovery falls back to LLDP neighbour direction. Where a neighbour advertises no management IP, LinkSight offers it as a candidate and resolves the address from its chassis MAC with an ARP sweep of the local subnet — or you can type the address yourself.
• If a switch in the chain does not answer, discovery stops there and presents the last reachable segment rather than failing outright.

Prerequisites: SNMP v2c read access on the managed switches. The read community is prompted once at the start of discovery and kept in RAM for the process lifetime — never written to disk, never sent anywhere.

Privacy

No historical logs, no background tracking, no active scanning, no telemetry, no account. Credentials and SNMP communities stay in memory. LinkSight reports what the wire already says.

Source

bryjogar/linksight — issues and pull requests welcome there. The README carries the full technical detail, including the build scripts and the release workflow.