┌─────────────────────────────────────────────────────┐
│ Analysis Summary                                    │
├─────────────────────────────────────────────────────┤
│ Type: Library                                       │
│ Primary Language: python + markdown + yaml          │
│ LOC: 181K                                           │
│ Test Files: 85                                      │
│ Architecture: python library                        │
│ Confidence: High                                    │
└─────────────────────────────────────────────────────┘

Analyzed: eaf2e556 from 2025-10-02

Impacket: Network Protocol Implementation Library for Security Research

Impacket is a Python library providing low-level programmatic access to network protocols, with particular focus on SMB, MSRPC, and Windows authentication mechanisms. Originally created by SecureAuth and now maintained by Fortra’s Core Security team, the library serves as both a protocol implementation toolkit and a collection of security research tools.

The codebase spans 181,424 lines across 326 files, implementing protocols including Ethernet, IP, TCP/UDP, SMB1-3, MSRPC, Kerberos, NTLM, and portions of MSSQL/LDAP. The library provides both packet construction/parsing capabilities and high-level protocol implementations for security testing scenarios.

Quick Start

python3 -m pipx install impacket

For development version:

git clone https://github.com/fortra/impacket
cd impacket
python3 -m pipx install .

Time to first result: ~2 minutes (installation and basic import)

Docker support is available:

docker build -t "impacket:latest" .
docker run -it --rm "impacket:latest"

Alternative Approaches

Architecture and Implementation

The codebase demonstrates a builder pattern approach for protocol data handling. The wps.py module (lines 26-60) shows converter classes for different data types:

class ArrayBuilder(object):

    def from_ary(self, ary):
        return ary

    def to_ary(self, value):
        return array.array("B", value)
    
class ByteBuilder(object):

    def from_ary(self, ary):
        return ary[0]
    
    def to_ary(self, value):
        return array.array('B', [value])

The NumBuilder class handles network byte-order conversion (impacket/wps.py:49-60):

class NumBuilder(object):
    """Converts back and forth between arrays and numbers in network byte-order"""
    
    def __init__(self, size):
        """size: number of bytes in the field"""
        self.size = size
    
    def from_ary(self, ary):
        if len(ary) != self.size:
            raise Exception("Expected %s size but got %s" % (self.size, len(ary)))
        return reduce( lambda ac, x: ac * 256 + x, ary, 0)

Authentication handling shows hash parsing capabilities in the test suite (tests/init.py:77-96):

obj.lmhash, obj.nthash = obj.hashes.split(':')
obj.blmhash = unhexlify(obj.lmhash)
obj.bnthash = unhexlify(obj.nthash)

The utility functions demonstrate target parsing for various authentication formats (tests/misc/test_utils.py:21-40):

targets = {
    "": ("", "", "", ""),
    "HostName": ("", "", "", "HostName"),
    "UserName@HostName": ("", "UserName", "", "HostName"),
    "UserName:Password@HostName": ("", "UserName", "Password", "HostName"),
    "DOMAIN/UserName:Password@HostName": ("DOMAIN", "UserName", "Password", "HostName"),
}

Common Tool Usage

The repository contains 131 example files demonstrating various security testing scenarios. While specific tool implementations weren’t fully analyzed in the provided samples, the test infrastructure shows support for:

• Hash-based authentication testing
• Domain credential parsing
• Machine account authentication
• AES key handling for Kerberos

Performance Characteristics

Package Structure:

• Core library: ~180,074 lines of Python
• Test suite: 85 test files
• Examples/tools: 131 files
• Dependencies: 11 external packages

Runtime Dependencies:

• Core crypto: pycryptodomex, pyOpenSSL
• ASN.1 support: pyasn1, pyasn1_modules
• LDAP functionality: ldap3, ldapdomaindump
• Web interface: flask
• Platform compatibility: pyreadline3 (Windows)

Other Considerations:

• Extensive protocol coverage requires significant memory for full imports
• Network operations depend on target responsiveness
• Some tools may trigger security software due to their nature

Best for: Security research, penetration testing, protocol analysis, and Windows authentication testing in authorized environments.

Ethical and Legal Context

This is a security research tool. Important considerations:

• Designed for authorized security testing and research only
• Requires explicit written authorization before use in any environment
• Unauthorized use may violate computer fraud laws (CFAA in US, Computer Misuse Act in UK, etc.)
• Often flagged by antivirus software (expected behavior for security tools)
• Dual-use nature: legitimate security research vs. potential malicious use

When to Use Impacket

The evidence suggests this project fits well for:

• Security researchers needing low-level protocol access to Windows authentication mechanisms
• Penetration testers requiring SMB/MSRPC interaction capabilities in authorized engagements
• Protocol analysts studying Windows network communication patterns
• Developers building security tools that need to interact with Windows domain environments

Consider alternatives when:

• General packet crafting is needed beyond Windows protocols (Scapy offers broader coverage)
• High-level exploitation frameworks are preferred (Metasploit provides more automation)
• Simple network discovery is the primary goal (Nmap offers better reconnaissance features)
• Legal authorization for security testing cannot be obtained (tool requires explicit permission)