LangChain Integration

LangChain agents use Python httpx as their default HTTP client, producing distinctive JA4 TLS fingerprints. CounterAgent identifies LangChain traffic by correlating JA4 fingerprints with User-Agent patterns and request timing.

Known Fingerprints

Framework	JA4	HTTP Client	Notes
LangChain 0.2.x	`t13d3514h2_bfa337485184_*`	httpx	Python ssl module, 35 ciphers
LangChain + requests	`t13d351300_bfa337485184_*`	urllib3	Same cipher hash, different extension hash
LangServe	`t13d3514h2_bfa337485184_*`	httpx	Server-side deployment

Detection Signals

User-Agent: langchain-python/0.2.x (when not spoofed)
JA4H: httpx header ordering pattern (Host, Accept, Accept-Encoding, Connection)
Request patterns: sequential API calls with 50-200ms intervals
Path patterns: /api/, /v1/, /invoke, /stream

Using CounterAgent with LangChain

from langchain_core.tools import tool
from counteragent import Client

ca = Client(api_key="ca_live_...")

@tool
def check_agent(user_agent: str, ja4: str = None) -> dict:
    """Check if a request is from a known AI agent."""
    return ca.detect(user_agent=user_agent, ja4=ja4)

LangChain Integration

Known Fingerprints

Detection Signals

Using CounterAgent with LangChain

Related