Python 3.4：未知格式代码“x”

Question

我对 Python3 中的数据包嗅探器有疑问。

python 版本：3.4

我遵循了一些有效的教程，但不是在我的计算机上。 此代码必须获取 mac 地址，将其转换为字符串，并且在 main() 方法中应该向我打印目标 mac、源 mac 和协议。

代码：sniffer_demo.py

import socket
import struct
import textwrap

def main():
    conn = socket.socket(socket.AF_PACKET, socket.SOCK_RAW, socket.ntohs(3))

    while True:
        raw_data, addr = conn.recvfrom(65536)
        # one's and zero's put to the method ehternet_frame
        dest_mac, src_mac, eth_proto, data = ethernet_frame(raw_data)
        print('\nEthernet Frame:')
        print('Destination: {}, Source: {}, Protocol: {}'.format(dest_mac, src_mac, eth_proto))


# Unpack ethernet frame
def ethernet_frame(data):
    dest_mac, src_mac, proto = struct.unpack('! 6s 6s H', data[:14])
    return get_mac_addr(dest_mac), get_mac_addr(src_mac), socket.htons(proto), data[14:]


# Return properly formatted MAC address: (ie AA:BB:CC:DD:EE:FF)
def get_mac_addr(bytes_addr):
    bytes_str = map('{:02x}'.format, bytes_addr)
    return ':'.join(bytes_str).upper()

main()

错误是：

Traceback (most recent call last):
  File "sniffer_demo.py", line 28, in <module>
    main()
  File "sniffer_demo.py", line 11, in main
    dest_mac, src_mac, eth_proto, data = ethernet_frame(raw_data)
  File "sniffer_demo.py", line 19, in ethernet_frame
    return get_mac_addr(dest_mac), get_mac_addr(src_mac), socket.htons(proto), data[14:]
  File "sniffer_demo.py", line 24, in get_mac_addr
    bytes_str = map('{:02x}'.format, bytes_addr)
ValueError: Unknown format code 'x' for object of type 'str'

如何解决？

Answer 1

在尝试重现时，您的代码似乎完全按预期工作。我没有看到任何shebang-line。您确定使用python3 执行吗？

# python3.4 snif2.py 的示例输出：

Ethernet Frame:
Destination: A4:17:31:xx:xx:xx, Source: 00:0C:F6:xx:xx:xx, Protocol: 8

Ethernet Frame:
Destination: 00:0C:F6:xx:xx:xx, Source: A4:17:31:xx:xx:xx, Protocol: 8
^CTraceback (most recent call last):
  File "snif2.py", line 27, in <module>
    main()
  File "snif2.py", line 9, in main
    raw_data, addr = conn.recvfrom(65536)
KeyboardInterrupt

Answer 2

将您的 Python 更新到 3.6 版。