The Tool Desk
Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →When a program fails with bind: address already in use, Portop offers an interactive way to see what is listening, identify the process behind it and, when available, connect it to a systemd service or Docker container. It is a focused investigation tool—not a replacement for ss, lsof, Wireshark or Docker’s own tools.
What Portop shows
Portop is an open-source terminal UI written in Go. Its live table displays network activity, including listening ports and established connections, and attempts to associate sockets with the processes that own them. Where the system exposes enough information, it can also show related services or containers. Luca Padovan, the project’s author, sums up the goal as: “See a port. Understand what’s behind it. Act on it.”
Selecting a process and pressing Enter opens details such as its command line, executable, working directory, user, memory use, thread count and start time. The interface supports search and filtering, keyboard navigation and mouse input. It can also copy information, open a local web service in a browser, or terminate a process.
How it helps diagnose a port conflict
- Find the listener. Use Portop’s live view to locate the port involved in the bind error. Filtering can narrow the list by port or process name.
- Inspect its owner. Open the process details to see the command, executable, user and other available process information.
- Check its context. On Linux, Portop can associate a process with a systemd service or Docker container when that relationship can be derived from cgroups.
- Choose an action. Copy the details, open a local web service in a browser, or terminate the process from the interface. Before stopping anything, confirm that it is safe to interrupt; a listener may belong to a service you still need.
Linux, services and containers
According to Padovan’s project description, Linux port mapping reads /proc/net/tcp, /proc/net/tcp6, /proc/net/udp and /proc/net/udp6, then matches socket inodes to processes by walking /proc/<pid>/fd. Systemd and Docker associations are derived primarily from cgroups. These links add context to a socket listing; they do not guarantee that every process or service will be visible to every user.
#1 Best Overall
- VERSATILE CABLE TESTING: Cable tester for data (RJ45) terminated cables and patch cords, ensuring comprehensive testing capabilities
- LARGE BACKLIT LCD: Backlit LCD display enables easy reading of pin-to-pin wiremap results, even in low-lit areas
- COMPREHENSIVE FAULT DETECTION: Test for Open, Short, Miswire, Split-Pair faults, Cross-over, and Shield, providing thorough fault detection
- INTUITIVE USER INTERFACE: User-friendly interface with three buttons and simple, easy-to-identify test responses, ensuring a smooth testing experience
- MULTIPLE TONE GENERATOR STYLES: Tone on a single wire, wire pair, or all 8 conductor wires using the multiple style tone generator (solid/warble); requires probe Cat. No. VDV500-123 (sold separately)
Linux permissions constrain which processes a user can inspect. The author says running Portop with sudo can provide additional visibility when needed. Use elevated privileges only when appropriate, and take care when acting on processes you do not own or recognize.
Check Docker Compose port mappings
For a Compose project, the described command is:
portop --compose ./my-stack
Compose mode compares configured published ports with listeners. It can help flag expected mappings, conflicts, unused ports and dynamic mappings. Docker information can also help determine whether a listener belongs to the Compose service you expect. This is a way to investigate configuration against current listeners, not a substitute for understanding what the project intends to expose.
Rank #2
- VERSATILE CABLE TESTING: Cable tester tests voice (RJ11/12), data (RJ45), and video (coax F-connector) terminated cables, providing clear results for comprehensive testing on unenergized Ethernet cables (not designed to test PoE)
- EXTENDED CABLE LENGTH MEASUREMENT: Measure cable length up to 2000 feet (610 m), allowing for precise cable length determination
- COMPREHENSIVE FAULT DETECTION: Test for Open, Short, Miswire, or Split-Pair faults, ensuring thorough fault detection and identification
- BACKLIT LCD DISPLAY: Backlit LCD screen displays cable length, wiremap, cable ID, and test results, ensuring easy readability in various lighting conditions
- EFFICIENT CABLE TRACING: Trace cables, wire pairs, and individual conductor wires using the multiple style tone generator (requires analog probe Cat. No. VDV500-123, sold separately), simplifying cable tracing tasks
JSON, baselines and monitoring
Portop also has command-line workflows for scripting and checking changes. The project description lists these options:
portop --jsonfor JSON output.portop --compose ./my-stack --jsonfor JSON output in Compose mode.- Starting with a port or process-name filter to narrow results.
--save-baselineto save listening ports as a baseline, then--diffto compare against it. The description notes that--diffcan return a nonzero exit code when it finds changes.--watch-newto watch for new listening ports.
These options are useful when a developer wants to inspect port changes from a script or keep an eye on newly opened listeners. Check the installed version’s help or the project’s current documentation for exact option behavior before relying on it in automation.
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1Scan for outdated or missing drivers - takes under a minute2Repair Windows errors before they cause bigger problems3Fix the driver behind crashes, sound loss and screen glitchesRank #3
- Multifunctional NOYAFA NF-8508 Network Cable Tester: There are nine features to meet your needs. Continuity Testing, Cable Scan, Port Flash, Length Measurement, POE Power Supply Test, QC testing, Optical Power Meter, VFL and NVC function.It is perfectly suited for various engineering cabling projects, network troubleshooting, network equipment maintenance and testing scenarios. Its precise cable scanning and fault localization capabilities help you effortlessly pinpoint the root cause of issues.
- 7 WAVELENGTHS OPTICAL POWER METER: NF-8508 network cable tester can measure 7 standard wavelengths, 850/1300/1310/1490/1550/1625/1650, power detecting range(dBm): -70 ~ +10. Its power detection range spans from -70 dBm to +10 dBm, supporting FC/SC/ST connectors. It enables precise fiber optic power measurement, helping users efficiently assess fiber signal strength and ensure healthy fiber link operation. It effortlessly detects attenuation issues within fibers, thereby safeguarding fiber network stability.
- High Efficiency Visual Fault Locator: Easy identification of fiber breakpoints, poor connections, bending or cracking. Excellent for finding the right fiber to splice or quickly finding a break. Emmiting Energy: standard wavelenth: 650nm. Fast flashing, slow flashing, high precison.The built-in self-calibration ensures stable long-term performance, and Class IIIa laser (output<5mW) ensures safe daily operation.
- PORT FLASHING:The indicator light on the connection port in the NF-8508 device flashes to help accurately locate the cable. Displays port information, including operating speed, duplex mode, and negotiation settings. Port lights flash on the same screen to show the port's operating speed, making it easy to pinpoint lines and ports.
- PoE Testing and Cable Length Test: PoE testing can check cable mapping polarity and voltage of PoE network switches, withstand 60VDC. Automatically detects and switches between 10M/100M/1000M modes, Includes cable tracking, short circuit test, interruption of circuit test and etc The RJ45 cable tester can quickly measure the length of the cable with a range of 200m. Not only network cables, but also phone lines and BNC cables.
Platform support and installation
Padovan’s article lists Linux builds for amd64, arm64, armv7 and armv6, plus .deb and .rpm packages, and macOS builds for Intel and Apple Silicon. The macOS implementation uses native lsof and ps rather than Linux’s /proc filesystem. The article describes the project as MIT licensed and says contributions are welcome.
The article lists Go installation with go install github.com/padovanl/portop/cmd/portop@latest, a shell installer and GitHub releases as ways to obtain Portop. Release assets, supported platforms and installation instructions can change; consult the project’s current repository and release page before installing:
Rank #4
- Automatically runs all tests and checks for continuity, open, shorted and crossed wire pairs. Visible LED status display.
- Cable state testing (2-wire): Line DC detecting, anode and cathode determination,Ringing signal detecting open, short and cross circuit testing
- Cable Type: RJ11 Telephone cable and RJ45 LAN cable
- Connectors: Ethernet Cat 5, Ethernet Cat 5e, Ethernet Cat 6, Ethernet Cat 7, RJ11 6P and RJ45 8P
- Power Source: DC9V Battery Required (not included)
When Portop is—and is not—the right tool
Portop’s value is bringing port, process and available service or container context into one interactive view. That makes it convenient when the immediate question is “what owns this listener?” Its Compose comparison and JSON or change-checking options extend the same investigation to configuration and scripts.
It is not presented as a general network analyzer: Wireshark serves a broader packet-analysis purpose, while ss, lsof and Docker tooling remain useful for their own inspection workflows. Choose Portop when the convenience of connecting a visible socket to its likely owner is the problem to solve, and remember that permissions and platform-specific data sources affect what it can identify.
Quick Recap
Best Value
- Multi-Function Network Cable Tester: Supports RJ45 (CAT5, CAT5e, CAT6, CAT6A, CAT7) and RJ11 telephone cables. Quickly detects continuity, short circuits, open wires, miswiring, and cable shielding status, ensuring your LAN or phone lines are correctly wired and ready to use.
- Fast/Slow Mode with LED Indicators: Switch between fast and slow scan speeds to identify wiring issues more precisely. LED lights on both master and remote units show wire order, making it easy to spot errors like open pairs or misaligned pins at a glance.
- Split-Type Design for Long-Distance Testing: Master and remote units can be detached and used separately, allowing you to test both ends of a long cable run, ideal for wall-mounted ports, long runs, or structured cabling. Perfect for home, office, or professional IT setups.
- Compact, Lightweight & Durable: Ergonomically designed with sturdy ABS housing, this pocket-sized tester is ideal for on-the-go network engineers, DIYers, and electricians. It’s your go-to toolkit for cable maintenance, upgrades, or new installations.
- Safe & Easy to Use: Simple one-button operation makes testing quick and hassle-free. LED indicators clearly show wiring status, while the G light instantly identifies shielded (FTP/STP) or unshielded (UTP) cables. Supports safe testing of telephone lines with typical voltages under 48-72V, ideal for both home and professional use.
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