I am learning tcpdump recently, but I have some troubles now. I have already search them in google and there is nothing can help me solve my problem. If you know the answer, please help me. Thank you very much.
I want to know the expressions' meanings, the following are what make me confused:
ip&0xf)<<2 tcp&0xf0)>>2 ip[2:2] tcp[20:2]=0x4745 or tcp[20:2]=0x4854