network-diagnostics

Network Diagnostics

When to Use This Skill

Scenario	Use this skill	Alternative
Trace the route to a remote host	Yes (trippy)
Diagnose packet loss or high latency on a path	Yes (trippy)
Compare ping latency across multiple endpoints	Yes (gping)
Find what process is listening on a port	Yes (ss)
Count established connections to a service	Yes (ss)
Inspect local socket states (TIME_WAIT, etc.)	Yes (ss)
Scan all open ports on a remote host		network-discovery (RustScan, nmap)
Look up DNS records or check propagation		dns-tools (dog, dig)
Enumerate hosts on the local L2 segment		layer2-discovery (ARP/LLDP)
Inspect or configure the host's own IPs, links, or routes		interface-state (ip)
Benchmark HTTP endpoint throughput		http-load-testing (oha)
See real-time per-process bandwidth consumption		network-monitoring (bandwhich)

Expert knowledge for network connectivity troubleshooting using modern diagnostic tools that provide richer output than legacy alternatives.

Core Expertise

Tool Selection

Use Case	Tool	Why
Path analysis with latency	trippy	Combines traceroute + ping with TUI
Multi-host latency comparison	gping	Visual graphs, parallel pings
Local socket inspection	ss	Modern netstat replacement
Quick single-hop latency	gping	Faster feedback than trippy
Network path + ASN info	trippy	Built-in ASN/geo lookups

Advantages Over Legacy Tools

Modern	Legacy	Improvements
trippy	traceroute, mtr	TUI, jitter stats, ASN/geo, world map
gping	ping	Visual graphs, multi-host parallel
ss	netstat	Faster, more info, better filtering

Trippy - Modern Traceroute/MTR

Rust-based network path analyzer combining traceroute and ping with a rich TUI.

Essential Commands

# Basic traceroute with TUI
trip example.com

# Specify protocol mode
trip -m icmp example.com    # ICMP (default, needs root/caps)
trip -m udp example.com     # UDP (no root needed)
trip -m tcp example.com     # TCP

# TCP to specific port
trip -m tcp -p 443 example.com
trip -m tcp -p 80 example.com

# Specify source interface
trip -i en0 example.com
trip -i eth0 example.com

# Enable ASN lookups in TUI
trip --tui-as-mode asn example.com
trip --tui-as-mode prefix example.com

# Geo-location in TUI
trip --tui-geoip-mode short example.com
trip --tui-geoip-mode long example.com

Non-Interactive Output

# JSON output for parsing
trip example.com --mode json -c 10

# Dot format (Graphviz)
trip example.com --mode dot -c 10

# CSV format
trip example.com --mode csv -c 10

# Flows (path changes)
trip example.com --mode flows -c 10

# Silent mode (summary only)
trip example.com --mode silent -c 10

# Pretty print (no TUI)
trip example.com --mode pretty -c 10

Advanced Options

# Set packet count
trip example.com -c 100

# Set max TTL (hops)
trip example.com -t 30

# Set packet size
trip example.com -S 64

# First TTL to start from
trip example.com -f 5

# Parallel probes per hop
trip example.com -N 16

# Grace period after target reached
trip example.com -g 100ms

gping - Graphical Ping

Visual latency graphs with multi-host parallel ping support.

Essential Commands

# Basic ping with graph
gping example.com

# Multiple hosts (parallel comparison)
gping google.com cloudflare.com amazon.com

# Force IPv4/IPv6
gping -4 example.com
gping -6 example.com

# Specify interface
gping -i en0 example.com

# Simple graphics (ASCII, for terminals without unicode)
gping -s example.com

# Set buffer size (number of pings to display)
gping -b 100 example.com

Command Execution Mode

# Ping a command's execution time instead of host
gping --cmd "curl -s https://api.example.com/health"
gping --cmd "dig example.com"
gping --cmd "http https://api.example.com/status"

# Compare multiple commands
gping --cmd "curl -s localhost:3000" --cmd "curl -s localhost:8080"

Customization

# Set ping interval (seconds)
gping -n 0.5 example.com

# Watch specific timeout
gping -w 2 example.com

# Clear screen before starting
gping --clear example.com

ss - Socket Statistics

Modern replacement for netstat, faster and more informative.

Essential Commands

# All TCP connections
ss -t

# All UDP sockets
ss -u

# Listening sockets only
ss -l

# Show process info (requires root for other users' processes)
ss -p

# Numeric output (no DNS resolution)
ss -n

# Combined: listening TCP with process info, numeric
ss -tlnp

# Combined: all TCP/UDP listening sockets with processes
ss -tulnp

Filtering

# Filter by state
ss -t state established
ss -t state listening
ss -t state time-wait
ss -t state close-wait

# Filter by port
ss -t sport = :22
ss -t dport = :443
ss -t 'sport = :80 or dport = :80'

# Filter by address
ss -t src 192.168.1.0/24
ss -t dst 10.0.0.1

# Combined filters
ss -t 'sport = :443 and dst 10.0.0.0/8'

Statistics and Summary

# Socket summary statistics
ss -s

# Extended info (memory, congestion)
ss -e

# Timer info (retransmits, keepalives)
ss -o

# Memory usage
ss -m

# Full detail
ss -i

Common Investigations

# Find what's using a port
ss -tlnp | grep :8080
ss -tlnp 'sport = :8080'

# Count connections by state
ss -t state established | wc -l

# Find connections to specific host
ss -tn dst 192.168.1.100

# Monitor established connections to a service
watch -n 1 'ss -tn state established dport = :443 | wc -l'

Common Patterns

Connectivity Troubleshooting Workflow

# Step 1: Check if host responds
gping target.example.com

# Step 2: Analyze network path
trip target.example.com

# Step 3: Check local listening services
ss -tlnp

# Step 4: Verify outbound connectivity
ss -tn state established | grep target.example.com

Latency Comparison

# Compare multiple endpoints
gping primary.example.com secondary.example.com backup.example.com

# Compare DNS providers
gping 8.8.8.8 1.1.1.1 9.9.9.9

# Compare API endpoints
gping --cmd "curl -s api1.example.com" --cmd "curl -s api2.example.com"

Port Availability Check

# What's listening on common ports
ss -tlnp 'sport = :80 or sport = :443 or sport = :8080 or sport = :3000'

# Find all listening ports in a range
ss -tlnp 'sport >= :8000 and sport <= :9000'

Network Path Analysis

# Compare paths to different regions
trip us-east.example.com &
trip eu-west.example.com &
trip ap-southeast.example.com

# Analyze with ASN information
trip --tui-as-mode asn cdn.example.com

Agentic Optimizations

Context	Command
Quick latency check	gping -b 10 HOST 2>&1 | head -20
Path analysis (JSON)	trip HOST --mode json -c 5
Listening ports	ss -tlnp
Connection count	ss -tn state established | wc -l
Port in use	ss -tlnp 'sport = :PORT'
Multi-host compare	gping HOST1 HOST2 HOST3 -b 5
TCP path check	trip -m tcp -p 443 HOST --mode pretty -c 3

Quick Reference

Trippy Flags

Flag	Long	Description
-m	--mode	Protocol: icmp, udp, tcp
-p	--port	Target port (tcp/udp mode)
-i	--interface	Source interface
-c	--count	Number of probes
-t	--max-ttl	Maximum TTL/hops
-f	--first-ttl	Starting TTL
-S	--packet-size	Packet size in bytes
	--tui-as-mode	ASN display: asn, prefix
	--tui-geoip-mode	Geo display: short, long
	--mode	Output: tui, json, csv, dot, flows, silent, pretty

gping Flags

Flag	Long	Description
-4		Force IPv4
-6		Force IPv6
-i	--interface	Source interface
-s	--simple-graphics	ASCII-only output
-b	--buffer	Number of pings to display
-n	--interval	Ping interval (seconds)
-w	--watch-interval	Watch timeout
	--cmd	Ping command execution time
	--clear	Clear screen before starting

ss Flags

Flag	Description
-t	TCP sockets
-u	UDP sockets
-l	Listening only
-a	All sockets
-p	Show process
-n	Numeric (no DNS)
-e	Extended info
-o	Timer info
-m	Memory usage
-i	Internal TCP info
-s	Summary statistics

ss State Filters

State	Description
established	Active connections
listening	Listening sockets
time-wait	Waiting for timeout
close-wait	Waiting for local close
syn-sent	Connection initiating
syn-recv	Connection received

Installation

# macOS
brew install trippy gping

# ss is part of iproute2 on Linux (usually pre-installed)
# On macOS, use netstat instead (ss not available)

# Cargo (cross-platform)
cargo install trippy
cargo install gping

# Verify installations
trip --version
gping --version
ss --version  # Linux only

Platform Notes

• trippy: ICMP mode requires root or CAP_NET_RAW capability; UDP/TCP modes work without elevation
• gping: Works without elevation on all platforms
• ss: Linux only; use netstat -an on macOS for similar functionality

Resources

• Trippy: https://trippy.cli.rs/ | https://github.com/fujiapple852/trippy
• gping: https://github.com/orf/gping
• ss man page: https://man7.org/linux/man-pages/man8/ss.8.html