You're welcome. However, the checksum doesn't work out for "X-Cnection": >>> sum(ord(c) for c in "Connection") 1040 >>> sum(ord(c) for c in "X-Cnection"

You're welcome. However, the checksum doesn't work out for "X-Cnection": >>> sum(ord(c) for c in "Connection") 1040 >>> sum(ord(c) for c in "X-Cnection") 952 I suspect that in this specific scenario the checksum doesn't need to stay the same, but the packet size does.