Python Network Message Formatter (NF)

• Python library for generating binary network/packet data for protocol testing.
• Allows for writing network messages in a very human-readable form.
• Writes raw bytes to stdout which can be piped to tools such as netcat

Methods

• byte(b) - write 1 byte value

• word(w) - write 2 byte value

• dword(dw) - write 4 byte value

• qword(qw) - write 8 byte value

• bytes(b) - write an arbitrary list of bytes

• text(t) - write arbitrary text

• file(f) - write contents of file

• ip(ip) - write an IP address value represented as a string (with optional padding)

• mac(mac) - write a mac address value represented as a string

Examples

BGP Example bgp.py

Write a BGP common header followed by an OPEN message:

import nf

nf.qword(0xffffffffffffffff)  # Marker (bytes 0-8)
nf.qword(0xffffffffffffffff)  # Marker (bytes 8-16)
nf.word(13)                   # Length 
nf.byte(1)                    # Type
 
nf.byte(0)       # Version
nf.word(34232)   # Autonomous System
nf.word(120)     # Hold Time
nf.ip('1.1.1.1') # BGP Identifier
nf.byte(0)       # Optional Paremeters Length

Verify that the script generates the correct sequence of bytes

python bgp.py | hexdump -C  

Feed the output of this python script to a netcat pipe connected to a BGP router:

python bgp.py | netcat 192.168.1.1 179