实现Python Radius客户端CHAP认证
介绍: 在本篇文章中,我将向你展示如何使用Python实现Radius客户端CHAP认证。Radius(远程身份验证拨号用户服务)是一种网络协议,用于提供身份验证、授权和帐户信息。CHAP(Challenge-Handshake Authentication Protocol)是Radius协议中的一种认证方式,它通过挑战和握手的方式实现安全认证。
整体流程: 下面是实现Python Radius客户端CHAP认证的整体流程:
erDiagram
participant C as "Client"
participant S as "Server"
participant N as "NAS"
C --> S: 请求连接
S --> C: 发送挑战
C --> S: 发送响应
S --> C: 发送成功/失败信息
C --> N: 认证通过
详细步骤及代码:
- 导入所需的模块和库:
import hashlib
import random
import socket
- 定义Radius客户端类:
class RadiusClient:
def __init__(self, server_ip, server_port, shared_secret):
self.server_ip = server_ip
self.server_port = server_port
self.shared_secret = shared_secret
- 实现挑战和握手的过程:
class RadiusClient:
...
def authenticate_chap(self, username, password):
# 生成随机挑战字符串
challenge = ''.join([chr(random.randint(0, 255)) for _ in range(16)])
# 构建请求包
request_packet = self.build_request_packet(username, challenge)
# 发送请求包
response_packet = self.send_request(request_packet)
# 解析响应包
if response_packet is not None:
success = self.parse_response(response_packet, challenge, password)
if success:
print("Authentication successful")
else:
print("Authentication failed")
else:
print("No response received")
- 构建请求包:
class RadiusClient:
...
def build_request_packet(self, username, challenge):
# 构建请求包头部
header = bytearray()
header.append(1) # 包类型为Access-Request
header.append(1) # 包标识符为1(可随机生成)
# 构建用户名和密码字段
attributes = bytearray()
attributes.extend(self.build_attribute(1, username)) # 用户名属性类型为1
attributes.extend(self.build_attribute(3, self.generate_response(challenge))) # 密码属性类型为3
# 计算请求包长度
length = 20 + len(username) + len(challenge)
# 构建请求包
request_packet = bytearray()
request_packet.extend(header)
request_packet.extend(length.to_bytes(2, 'big'))
request_packet.extend(self.shared_secret.encode())
request_packet.extend(attributes)
return request_packet
- 发送请求包并接收响应包:
class RadiusClient:
...
def send_request(self, request_packet):
# 创建套接字并连接到服务器
client_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
client_socket.settimeout(5) # 设置超时时间为5秒
client_socket.connect((self.server_ip, self.server_port))
# 发送请求包
client_socket.send(request_packet)
try:
# 接收响应包
response_packet = client_socket.recv(1024)
return response_packet
except socket.timeout:
return None
- 解析响应包并验证认证结果:
class RadiusClient:
...
def parse_response(self, response_packet, challenge, password):
# 解析响应包
attributes = response_packet[20:] # 响应包从第21字节开始为属性字段
attribute_len = len(attributes)
i = 0
while i < attribute_len:
attribute_type = attributes[i]
attribute_length = attributes[i + 1]
attribute_value = attributes[i + 2:i + attribute_length]
if attribute_type == 2: # 匹配认证结果字段
return attribute_value == self.generate_response(challenge, password)
i += attribute_length
return False
- 计算响应值:
class RadiusClient:
...
def generate_response(self, challenge, password):
# 计算MD5哈希值
md5_hash = hashlib.md5()
md5_hash.update(challenge.encode())
md5_hash.update(self.shared_secret.encode())
md5_hash.update