Debugging tools

Jul 28, 2025

This article aims at summarizing all the tools used for debugging a web application or computer.

1. Networking

1.1. DNS

1. nslookup (Windows / Linux) allows to get information about DNS records.
2. dig Linux a more advanced debugging tool, often pre-installed on Linux.
3. dog Linux is a simple but powerful alternative to dig for DNS lookups.

1.2. Packet route analysis

1. traceroute Linux can trace a packet through its different hops on the WAN network. Uses the packet TTL (incremented one by one) to get this info.
2. tracert Windows Windows equivalent of traceroute
3. mtr Linux Powerful linux diagnostic tool. It combines traceroute and ping

1.3. Host accessibility

1. ping Linux / Windows
2. gping Linux is a graphical and multitarget alternative to ping.

1.4. IP host configuration

1. ip (Linux)
2. ipconfig Windows

1.5. Low-level packet analysis

1. tshark command-line, Using tshark
2. WireShark GUI

2. Operating-system informations

2.1. Linux

Some of these tools are taken from Michael Hausenblas's Learning Modern Linux excellent book.

2.1.1. System info

# Get info about distribution
cat /etc/*-release
# Get info about Linux release (kernel)
cat /proc/version
# Print all information related to the system
uname -a

2.1.2. Hardware info

cat /proc/cpuinfo
cat /proc/meminfo
cat /proc/diskstats
sudo dmidecode -t bios

2.1.3. RAM, Users, Processes

• RAM installed and free portion: free -ht
• Connected users on the system: w
• System metrics of a user [USER] (CPU load, ...): top -U [USER]
• List all processes: ps faux
• Find a particular process: ps -e | grep [process]

2.1.4. File info

• File details: stat [filename]
• Path to command: which [cmd]
• Find file: find /path -name "*.ext" or in combination with grep: find . -type f -exec grep -H NAME {};
• Create test file: dd if=/dev/zero of=testfile.dat bs=1024 count=1000 (creates a 1kB file with only zeros)

2.1.5. Redirections and pipes

• stdout: command 1> file or command > file
• stderr: command 2> file
• stdout and stderr combined: command &> file or command >file 2&>1
• Drop output: command > /dev/null
• stdin: command < file

2.1.6. 1.2.1.6 System performance

• Artificially generate CPU load: yes | tr \\n x | head -c 450m | grep z
• Disk space for user: du -h /home
• Free disk space: df -h
• Load test of a hard disk: dd if=/dev/zero of=/path/to/disk bs=1G count=1 oflag=direct

3. Command-line tools

3.1. Linux

• See list of modern command-line tools for Unix-based systems on ibraheemdev GitHub's page

• tail -f to follow a journal/log file