In the following example, we see how we define a function that will be executed every time a packet of type UDP is obtained when making a DNS request:
scapy> a = sniff(filter="UDP and port 53",count=100,prn=count_dns_request)
This function can be defined from the command line in this way. First we define a global variable called DNS_QUERIES, and when scapy finds a packet with the UDP protocol and port 53, it will call this function to increment this variable, which indicates there has been a DNS request in the communications:
>>> DNS_QUERIES=0>>> def count_dns_request(package):>>> global DNS_QUERIES>>> if DNSQR in package:>>> DNS_QUERIES +=1
