Introduction to Network Programming with Python Rafael Santos @Tucif Hacking.mx meetup 

● Why? ● Network Packets ● Packets and Python ● Demo Network Programming with Python 

Why? With most tools you won't build someting the author did not imagine. To stop being an script kiddie. It's fun! 

Let's talk a bit about networking How/Why does the internet work? How does my machine talk to others? 

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IP 

But what if the packet is.. manipulated? captured? sent to other place? ... 

Wait a minute.. Who creates the packets? Can I create my own packets? 

Scapy ● Written in Python ● Command-line interactive ● TCP,IP,ICMP,ARP,... ● Easy encapsulation ● Decodes but doesn't interpret 

Scapy Creating an IP packet: >>> ip = IP() >>> ip.dst = "127.0.0.1" >>> ip 

Sending packets send(IP(dst="10.1.99.2")/ICMP()/"HelloWorld") I can do that with a simple ping! 

Sending evil packets send(IP(src="10.1.99.100", dst=" 10.1.99.2")/ICMP()/"HelloWorld") 

Demo time! Let's build a Port Scanner! 

scanPacket = IP(dst='192.168.1.177')/TCP (dport=8080,sport=459) #sendReceive sr(scanPacket) Scanning Ports 

Interpreting results IP / TCP 192.168.1.185:(sport) > 192.168.1.177:(dport) S ==> IP / TCP 192.168.1.177:(dport) > 192.168.1.185:(sport) SA 

References Warriors of the Net (warriorsofthe.net) The TCP/IP Guide (TCPIPGuide.com) The Very Unofficial Dummies Guide to Scapy (scapy-guide.googlecode.com) Scapy Official docs (http://www.secdev. org/projects/scapy/doc/) 

Q & A @Tucif