UnicodeDecodeError: ‘ascii’ codec can’t decode byte 0xd1 in position 1: ordinal not in range(128) (Why is this so hard??)
One of the toughest things to get right in a Python program is Unicode handling. If you’re reading this, you’re probably in the middle of discovering this the hard way.

The main reasons Unicode handling is difficult in Python is because the existing terminology is confusing, and because many cases which could be problematic are handled transparently. This prevents many people from ever having to learn what’s really going on, until suddenly they run into a brick wall when they want to handle data that contains characters outside the ASCII character set.

Scapy is a powerful interactive packet manipulation program. It is able to forge or decode packets of a wide number of protocols, send them on the wire, capture them, match requests and replies, and much more. It can easily handle most classical tasks like scanning, tracerouting, probing, unit tests, attacks or network discovery (it can replace hping, 85% of nmap, arpspoof, arp-sk, arping, tcpdump, tethereal, p0f, etc.). It also performs very well at a lot of other specific tasks that most other tools can't handle, like sending invalid frames, injecting your own 802.11 frames, combining technics (VLAN hopping+ARP cache poisoning, VOIP decoding on WEP encrypted channel, ...), etc. See interactive tutorial and the quick demo: an interactive session (some examples may be outdated).