在python中生成一个欺骗性的UDP数据包

Question

how can i create a spoofed UDP packet using python sockets,without using scapy library. i have created the socket like this

sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) # UDP
sock.sendto(bytes('', "utf-8"), ('192.168.1.9', 7043))# 192.168.1.9dest 7043 dest port

Answer 1

I think you mean changing the source and destination addresses from the IP layer (on which the UDP layer is based).

To do so, you will need to use raw sockets. (SOCK_RAW), meaning that you have to build everything starting from the Ethernet layer to the UDP layer.

Honestly, without scapy, that's a lot of hard work. If you wanted to use scapy, it would take 2 lines:

pkt = Ether()/IP(src=“...”, dst=“...”)/UDP()/...
sendp(pkt)

I really advice you to use scapy. The code itself is quite small so I don't see a reason not to use it. It's defiantly the easiest in python

Answer 2

This is one of the first results for google searches like "spoofing udp packet python" so I am going to expand @Cukic0d's answer using scapy.

Using the scapy CLI tool (some Linux distributions package it separately to the scapy Python library ):

pkt = IP(dst="1.1.1.1")/UDP(sport=13338, dport=13337)/"fm12abcd"
send(pkt)

This sends a UDP Packet to the IP 1.1.1.1 with the source port 13338 , destination port 13337 and the content fm12abcd .

If you need to a certain interface for some reason (like sending over a VPN that isn't your default route) you can use send(pkt, iface='tun0') to specify it.

One difference to @Cukic0d's answer is that this solution is more flexible by sending a layer 3 packet with send instead of a layer 2 packet with sendp . So it isn't necessary to prepend the correct Ethernet header with Ether() which can cause issues in some scenarios, eg:

WARNING: Could not get the source MAC: Unsupported address family (-2) for interface [tun0]
WARNING: Mac address to reach destination not found. Using broadcast.