hexdump.md

Hexdump Comprehensive Cheatsheet

Installation Instructions

Windows

# Using Chocolatey
choco install hexdump

# Using MSYS2
pacman -S util-linux

Linux (Ubuntu/Debian)

sudo apt-get update
sudo apt-get install bsdmainutils

macOS

# Using Homebrew
brew install hexdump

# Already installed by default on macOS

Basic Commands

Standard Output Formats

1. Basic Hexdump

hexdump file

2. Canonical Hex+ASCII Display

hexdump -C file

3. Two-byte Hex Display

hexdump -x file

4. One-byte Octal Display

hexdump -b file

Format Specifiers

5. Custom Format

hexdump -e '16/1 "%02X " "\n"' file

6. Format with ASCII

hexdump -e '16/1 "%02X " "  |" 16/1 "%_p" "|\n"' file

7. Four-byte Words

hexdump -e '4/4 "%08X " "\n"' file

Offset Control

8. Skip Bytes

hexdump -s offset file

9. Limit Length

hexdump -n length file

10. Custom Offset Format

hexdump -e '"0x%08.8_ax  " 16/1 "%02X " "\n"' file

Data Analysis

11. Search for Pattern

hexdump -C file | grep "pattern"

12. Compare Files

cmp <(hexdump file1) <(hexdump file2)

13. Extract Specific Bytes

hexdump -s offset -n length -C file

Advanced Format Strings

14. Custom Byte Grouping

hexdump -e '8/1 "%02X " "  " 8/1 "%02X " "\n"' file

15. Include Decimal Values

hexdump -e '4/1 "%3d " "\n"' file

16. Mixed Hex and ASCII

hexdump -e '"%08.8_ax  " 8/1 "%02X " "  " 8/1 "%02X "' -e '"  |" 16/1 "%_p" "|\n"' file

File Analysis Techniques

17. Find String Patterns

hexdump -C file | grep -A1 -B1 "text"

18. Analyze File Headers

hexdump -n 16 -C file

19. Check File Type

hexdump -n 4 -C file

Binary Analysis

20. Analyze Executable Headers

hexdump -n 64 -C executable

21. Extract Sections

hexdump -s section_offset -n section_size -C file

22. Find Null Sequences

hexdump -C file | grep "00 00 00 00"

Special Uses

23. Memory Dump Analysis

hexdump -C memory.dump

24. Network Packet Analysis

hexdump -C packet.cap

25. Firmware Analysis

hexdump -C firmware.bin

Advanced Usage

Custom Scripts

26. Pattern Matching Script

#!/bin/bash
hexdump -C "$1" | grep -A2 -B2 "$2"

27. Binary Diff Script

#!/bin/bash
diff <(hexdump -C "$1") <(hexdump -C "$2")

Format String Examples

28. 32-bit Integer Format

hexdump -e '4/4 "0x%08x " "\n"' file

29. Float Format

hexdump -e '4/4 "%f " "\n"' file

30. Mixed Format

hexdump -e '"%-8_ad  " 8/1 " %02x" "  " 8/1 " %02x" "  |" 16/1 "%_p" "|\n"' file

Practical Applications

File Format Analysis

31. PDF Header Analysis

hexdump -n 32 -C file.pdf

32. ZIP File Analysis

hexdump -C file.zip | grep "PK"

33. Image File Analysis

hexdump -n 8 -C image.jpg

Malware Analysis

34. String Extraction

hexdump -C malware.bin | grep -i "http"

35. Signature Detection

hexdump -C file | grep -A4 "MZ"

Data Recovery

36. Find File Headers

hexdump -C disk.img | grep -A16 -B16 "PDF"

37. Carve File Boundaries

hexdump -C disk.img | grep -A32 "FFD8"

Best Practices

Performance Tips

38. Large File Handling

# Use dd to split large files
dd if=large_file bs=1M count=1 | hexdump -C

39. Efficient Searching

hexdump -C file | grep --color=auto pattern

Analysis Workflow

40. Initial Assessment

# Quick file overview
head -c 512 file | hexdump -C

41. Detailed Analysis

# Full file with custom format
hexdump -e '"%08.8_ax  " 16/1 "%02X " "  |" 16/1 "%_p" "|\n"' file

Common Issues and Solutions

42. File Encoding

# Handle different encodings
iconv -f utf-16 -t utf-8 file | hexdump -C

43. Large Files

# Split analysis
split -b 1M file chunk_
for f in chunk_*; do hexdump -C "$f"; done

Scripting Examples

44. Automated Analysis

#!/bin/bash
for file in *.bin; do
    echo "Analyzing $file..."
    hexdump -C "$file" | grep -A4 -B4 "pattern"
done

45. Format Conversion

#!/bin/bash
hexdump -e '16/1 "%02X" "\n"' file > file.hex