Scapy生成Dot11元素时添加'c2'字节的异常原因及解决方法问询

The Root Cause #

That extra c2 byte is a result of unintended UTF-8 encoding in Scapy. Here's the breakdown:

• When you pass a standard Python string (like "\\xac") as the info value for a Dot11Elt object, Scapy assumes it's text that needs UTF-8 encoding.
• The byte 0xac falls outside the 7-bit ASCII range (0x00-0x7F). In UTF-8, values above 0x7F get converted into multi-byte sequences—specifically, 0xac becomes c2 ac, which is why you see that extra c2 inserted.

The Fix: Use Raw Byte Strings #

To stop Scapy from encoding your binary data, you need to pass a byte string (prefixed with b) instead of a regular string for the info field. This tells Scapy to treat the data as raw binary, not text that needs formatting.

Wrong Approach (Causes the c2 Byte)

from scapy.layers.dot11 import Dot11, Dot11Elt, Dot11Beacon
from scapy.sendrecv import sendp

# Regular string triggers UTF-8 encoding
bad_element = Dot11Elt(ID=0x0f, info="\xac")
beacon_frame = Dot11(type=0, subtype=8, addr1="ff:ff:ff:ff:ff:ff", addr2="00:11:22:33:44:55", addr3="00:11:22:33:44:55") / Dot11Beacon(cap="ESS") / bad_element
sendp(beacon_frame, iface="wlan0mon", loop=1)

Correct Approach (Eliminates the c2 Byte)

from scapy.layers.dot11 import Dot11, Dot11Elt, Dot11Beacon
from scapy.sendrecv import sendp

# Byte string preserves raw binary data
good_element = Dot11Elt(ID=0x0f, info=b"\xac")
beacon_frame = Dot11(type=0, subtype=8, addr1="ff:ff:ff:ff:ff:ff", addr2="00:11:22:33:44:55", addr3="00:11:22:33:44:55") / Dot11Beacon(cap="ESS") / good_element
sendp(beacon_frame, iface="wlan0mon", loop=1)

Quick Check #

After updating your code, capture the beacon frame with Wireshark or a similar tool. You should see the 0f element ID followed directly by ac—no extra c2 byte will be present.

内容的提问来源于stack exchange，提问作者I'm Shyan