ip/tcp packet decoding without wireshark
My guess is that what you are seeing is a Level 2 Ethernet frame and therefore the preamble is missing. Also the Ethernet checksum seems to be missing. In this case everything seems to line up (the packet type inside the Ethernet frame, the IPv4 version, the IPv4 packet length, the packet type, i.e. TCP, inside the IP packet,  ...). Then you'd read your packet as in the picture.



The TCP payload is

474554202f20485454502f312e300d0a
557365722d4167656e743a2057676574
2f312e31312e340d0a4163636570743a
202a2f2a0d0a486f73743a207777772e
696574662e6f72670d0a436f6e6e6563
74696f6e3a204b6565702d416c697665
0d0a0d0a


and decodes to:

GET / HTTP/1.0
User-Agent: Wget/1.11.4
Accept: */*
Host: www.ietf.org
Connection: Keep-Alive


which is coherent with the fact that the destination port is 80.