onport

See what's listening on your ports.

onport is a cross-platform CLI tool that instantly shows what processes are listening on which ports. One command replaces lsof -i, ss -tlnp, netstat -an, and Get-NetTCPConnection.

Downloading? Pre-built binaries are available on GitLab — see the latest release for Linux, Windows, macOS, and FreeBSD downloads.

Features

• Instant: Shows all listening ports in under 50ms
• Beautiful: Colored, aligned, scannable table
• Cross-platform: Linux, macOS, Windows, FreeBSD
• Port ranges: onport 3000-3002 or onport 80 3000-3002
• Docker-aware: Automatically labels ports with container names
• Watch mode: Live-updating display with new/gone highlighting
• Kill mode: Kill a process by port with a single command
• Single-port detail view: Full command line, start time, open FDs, process tree
• Service names: Well-known ports (ssh, http, https, postgres, redis, etc.) shown in SERVICE column and in JSON output
• REMOTE column: Remote address visible in both table and watch mode
• Filtering: Filter by process name, username, PID, or IP version (IPv4/IPv6)
• Sorting: Sort output by port, PID, name, user, state, or protocol
• Wide mode: Show full untruncated process names
• Watch interval: Control watch refresh rate with --interval
• Shell completions: Generate completions for bash, zsh, fish, and PowerShell
• Graceful degradation: Missing info shows ?, never crashes

Installation

Pre-built binaries (fastest)

# Linux / macOS — one-liner
curl -sSfL https://gitlab.cherkaoui.ch/HadiCherkaoui/onport/-/raw/main/install.sh | bash

# Windows — PowerShell one-liner
irm https://gitlab.cherkaoui.ch/HadiCherkaoui/onport/-/raw/main/install.ps1 | iex

Or download a binary directly from the latest release.

cargo (crates.io)

cargo install onport

From source

# clone and build
git clone https://gitlab.cherkaoui.ch/HadiCherkaoui/onport
cd onport
cargo build --release

Platform support

Platform	Tested	CI build
Linux x86_64	✅ Tested	musl static binary
Linux ARM64	✅ Tested	GNU binary
Windows x86_64	✅ Tested	mingw cross-compile
macOS x86_64	⚠️ Untested	cross-compiled via cargo-zigbuild
macOS ARM64	⚠️ Untested	cross-compiled via cargo-zigbuild
FreeBSD x86_64	⚠️ Build from source (cargo build --release)	zig sysroot missing libexecinfo

Usage

# Show all listening ports
onport

# Filter to specific ports
onport 3000
onport 3000 8080
onport :3000 :8080

# Port ranges
onport 3000-3002
onport 80 3000-3002

# Show all states (not just LISTEN)
onport --all

# TCP or UDP only
onport --tcp
onport --udp

# JSON output for scripting
onport --json

# Disable colors
onport --no-color

# Skip Docker enrichment (faster when Docker socket is slow)
onport --no-docker

# Kill the process on a port
onport --kill 3000
onport -k 3000

# Force kill (no confirmation prompt)
onport --kill --force 3000
onport -k -f 3000

# Send a specific signal when killing
onport -k --signal HUP 8080
onport -k --signal 9 3000

# Live-updating watch mode (press q to quit)
onport --watch
onport -w
onport -w 3000

# Watch mode with custom refresh interval (seconds, minimum 0.5)
onport -w --interval 1.0
onport -w -i 5

# Filter by process name (case-insensitive substring)
onport --name nginx
onport -n node

# Filter by username (case-insensitive substring)
onport --user root
onport -u SYSTEM

# Filter by PID
onport --pid 1234

# Show only IPv4 or IPv6 sockets
onport --ipv4
onport -4
onport --ipv6
onport -6

# Sort results
onport --sort name         # sort by process name
onport --sort pid          # sort by PID
onport --sort user         # sort by username
onport --sort state        # sort by socket state
onport --sort proto        # sort by protocol
onport --sort port         # sort by port number (default)

# Show full process names without truncation
onport --wide
onport -W

# Generate shell completions
onport --completions bash > ~/.bash_completion.d/onport
onport --completions zsh > ~/.zsh/completions/_onport
onport --completions fish > ~/.config/fish/completions/onport.fish
onport --completions powershell > $PROFILE.CurrentUserAllHosts

Options

Flag	Short	Description
--tcp		Show only TCP sockets
--udp		Show only UDP sockets
--all		Show all socket states, not just LISTEN
--json		Output as JSON for scripting
--no-color		Disable colored output
--no-docker		Disable Docker container name detection
--kill	-k	Kill the process on the specified port
--force	-f	Force kill without confirmation (with --kill)
--signal <SIG>		Signal to send: name (HUP, TERM, KILL) or number (9). Only with --kill
--watch	-w	Live-updating watch mode (press q to quit)
--interval <SECS>	-i	Refresh interval for watch mode in seconds (default: 2.0, minimum: 0.5)
--name <NAME>	-n	Filter by process name (case-insensitive substring)
--user <USER>	-u	Filter by username (case-insensitive substring)
--pid <PID>		Filter by PID
--ipv4	-4	Show only IPv4 sockets
--ipv6	-6	Show only IPv6 sockets
--sort <FIELD>		Sort by: port (default), pid, name, user, state, proto
--wide	-W	Disable process name truncation (show full names)
--completions <SHELL>		Generate shell completions: bash, zsh, fish, powershell, elvish

Example Output

Standard listing:

 PORT   SERVICE    PROTO  ADDRESS          PROCESS          PID    USER       STATE        REMOTE
   22   ssh        tcp    *                sshd             1204   root       LISTEN       —
   80   http       tcp    *                nginx           14201   www        LISTEN       —
 3000   —          tcp    *                node            14523   hadi       LISTEN       —
 5432   postgres   tcp    *                postgres         9102   postgres   LISTEN       —       [docker: my-postgres]
 8080   http-alt   tcp    127.0.0.1        traefik          8832   root       LISTEN       —       [docker: traefik]

Single-port detail view (onport 5432):

 PORT   SERVICE    PROTO  ADDRESS          PROCESS          PID    USER       STATE        REMOTE
 5432   postgres   tcp    *                postgres         9102   postgres   LISTEN       —       [docker: my-postgres]

  Command:    postgres -D /var/lib/postgresql/data
  Started:    3h 22m ago
  Open FDs:   47
  Tree:       systemd → docker-containerd-shim → postgres

  Kill this process? [y/N]

Filtered by name (onport --name nginx --sort port):

 PORT   SERVICE    PROTO  ADDRESS   PROCESS   PID    USER   STATE
   80   http       tcp    *         nginx      8801   www    LISTEN
  443   https      tcp    *         nginx      8801   www    LISTEN

Well-Known Service Names

The SERVICE column shows standard names for common ports:

Port	Service	Port	Service
22	ssh	3306	mysql
25	smtp	3389	rdp
53	dns	5432	postgres
80	http	5672	amqp
443	https	6379	redis
1433	mssql	8080	http-alt
2049	nfs	9200	elastic
27017	mongodb	6443	kube-api

Ports without a standard name show —.

Comparison

Task	onport	lsof	ss	netstat
All listening ports	onport	lsof -iTCP -sTCP:LISTEN -nP	ss -tlnp	netstat -tlnp
What's on port 3000	onport 3000	lsof -i :3000	ss -tlnp sport = :3000	netstat -tlnp | grep 3000
Kill process on port	onport -k 3000	N/A	N/A	N/A
JSON output	onport --json	N/A	ss -tlnp -H -O	N/A
All connections	onport --all	lsof -i	ss -tanp	netstat -tanp
Live watch	onport -w	N/A	N/A	N/A
Filter by name	onport -n nginx	N/A	N/A	N/A
Filter by user	onport -u root	N/A	N/A	N/A
Sort by field	onport --sort name	N/A	N/A	N/A

License

GPL-3.0-or-later — Copyright (C) 2026 Hadi Cherkaoui