I’ve used scapy for years and found it especially useful when performing internal penetration tests. It has useful patterns for tasks like quickly putting toget

I’ve used scapy for years and found it especially useful when performing internal penetration tests. It has useful patterns for tasks like quickly putting together a custom DNS server, UDP source spoofing, walking all ICMP codes (or a quick and dirty ICMP redirect tool), or couple it with matplotlib and to estimate how many active hosts are communicating with a remote server based on TCP sequence numbers (I believe this is part of the scapy examples.) Coupled with interfaces to import and export PCAP files, it’s also a great way to learn about or explore/tamper with network protocols. The fact that it’s implemented in Python might scare some off, but I personally feel that this only adds to its usefulness since it can benefit from all of the external tooling and flexibility that comes with the language.