🐡 NetBSD Debugging Tools

NetBSD provides a comprehensive set of debugging and diagnostic tools designed for portability and reliability across diverse hardware platforms. Drawing from its strong BSD heritage, these utilities enable precise system analysis and troubleshooting.

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🔍 Core Debugging Utilities

strace – System Call Tracing¹

Traces system calls made by a process, useful for diagnosing hangs or unexpected behavior.

# Trace system calls of a command
strace ls

# Save trace output to file
strace -o trace.log ./my_program

# Follow child processes
strace -f daemon_program

¹ Note: May require installation via pkgsrc (pkgin install strace)

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ktrace / kdump – Kernel-Level Tracing

Native NetBSD kernel tracing facility for detailed process and kernel activity monitoring.

# Start tracing a process
ktrace ./my_app

# View trace results
kdump

# Trace specific system calls only
ktrace -t c ./network_program

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gdb – GNU Debugger

Standard debugger for analyzing compiled programs with symbolic debugging information.

# Load program into GDB
gdb ./program

# Run with arguments
(gdb) run arg1 arg2

# Set breakpoint at main
(gdb) break main

# Show backtrace
(gdb) bt

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📊 Performance Analysis Tools

top – Process Activity Monitor

Real-time display of system resource usage including CPU, memory, and process activity.

# Interactive top view
top

# Batch mode for scripting
top -b -n 1

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ps – Process Status

Detailed view of running processes with customizable output formats.

# All processes with full details
ps auxww

# Tree view of processes
ps axf

# Custom format output
ps -eo pid,ppid,cmd,%cpu,time

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vmstat – Virtual Memory Statistics

Reports virtual memory, process scheduling, disk I/O, and interrupt statistics.

# Display every 2 seconds
vmstat 2

# Show disk-specific stats
vmstat -i

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🗃️ Filesystem & Storage Diagnostics

fstat – File Status Information

Shows which files are currently open by processes.

# Show all open files
fstat

# Filter by process ID
fstat -p 1234

# Show network connections
fstat -n

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iostat – I/O Statistics

Monitors disk I/O performance and device utilization.

# Extended device statistics
iostat -x

# Update every 5 seconds
iostat 5

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disklabel – Disk Label Management

View and manage disk partition layouts and labels.

# Show disk label information
disklabel wd0

# Edit disk label (advanced)
disklabel -E wd0

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🌐 Network Troubleshooting

sockstat – Socket Statistics

Lists active sockets and associated processes (if available).

# Show listening sockets
sockstat -l

# All IPv4 connections
sockstat -4

# Specific protocol
sockstat -P tcp

⚠️ Note: Not all NetBSD versions include sockstat; alternative approaches below.

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Alternative Network Tools

# Show active connections with netstat
netstat -an

# List listening ports
netstat -an | grep LISTEN

# Interface statistics
netstat -i

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tcpdump – Packet Sniffer

Captures and analyzes network traffic packets.

# Capture on default interface
tcpdump

# Filter HTTP traffic
tcpdump port 80

# Write capture to file
tcpdump -w capture.pcap

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🧠 Memory Debugging

valgrind – Memory Error Detector¹

Detects memory leaks and invalid memory accesses.

# Check for memory errors
valgrind --tool=memcheck ./my_program

# Generate suppressions
valgrind --gen-suppressions=all ./my_program

¹ Available via pkgsrc: pkgin install valgrind

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/proc/*/status – Process Memory Info

Access process memory information directly from procfs (if mounted).

# Check process memory usage
cat /proc/1234/status | grep VmRSS

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🕵️‍♂️ Logs and System Messages

dmesg – Kernel Ring Buffer

Views boot-time messages and runtime kernel diagnostics.

# Recent kernel messages
dmesg | tail

# Highlight errors/warnings
dmesg -T | grep -E "(error|warning)"

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syslogd + logger – System Logging

Standard Unix logging facilities supported in NetBSD.

# Send custom log message
logger "Test log entry"

# View recent logs
tail /var/log/messages

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🧰 Advanced Diagnostic Tools

DDB – In-Kernel Debugger²

Built-in kernel debugger for live system analysis or crash dump examination.

Enable with kernel option:

options DDB

Commands:

# Show current backtrace
bt

# Continue execution
continue

# Show registers
show registers

² Requires kernel recompilation with DDB support.

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kgdb – Kernel Debugger³

Used for debugging the running kernel or crash dumps.

# Analyze core dump
kgdb /netbsd /var/crash/netbsd.core

³ Requires kernel debugging enabled and proper setup.

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🧾 Summary Table

Tool	Purpose
strace	System call tracing
ktrace	Kernel-level process tracing
gdb	Source-level debugging
fstat	Open file descriptor tracking
netstat	Network connection monitoring
tcpdump	Network packet capture
valgrind	Memory error detection
dmesg	Kernel diagnostic messages
DDB	In-kernel debugger

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🧠 Best Practices

✅ Use ktrace/kdump for native kernel-level tracing ✅ Leverage fstat for identifying file handle leaks ✅ Monitor system resources with vmstat and iostat ✅ Regularly review dmesg for hardware compatibility issues ✅ Combine tools for cross-layer diagnostics ✅ Keep logs organized for audit purposes

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🧾 See Also

• NetBSD Init and Services
• NetBSD Pkgsrc and Environment
• NetBSD Shell Basics
• Reference: BSD vs GNU Tools
• Patterns: Logging and Telemetry

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