/usr/lib/radare/bin/net-tcp is in radare-common 1:1.5.2-4.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 | #!/bin/sh
#; This TCP header can be aligned where you want becouse it is relative :)
#;
#; author: sha0
cat <<EOF
; s here
b 16
f tcp.sourceport
; s +16
b 16
f tcp.destport @ +16
; s +16
b 32
f tcp.seqnum @ +32
; s +32
b 32
f tcp.acknum @ +64
; s +32
b 4
f tcp.offset @ +96
; s +4
b 6
f tcp.reserved @ +100
; s +6
b 1
f tcp.urg @ +106
; s +1
b 1
f tcp.ack @ +107
; s +1
b 1
f tcp.psh @ +108
; s +1
b 1
f tcp.rst @ +109
; s +1
b 1
f tcp.syn @ +110
; s +1
b 1
f tcp.fin @ +111
; s +1
b 16
f tcp.window @ +127
; s +16
b 16
f tcp.chksum @ +143
; s +16
b 16
f tcp.urgptr @ +159
; s +16
b 24
f tcp.options @ +175
; s +24
b 8
f tcp.padding @ +199
; s +8
b 32
f tcp.data @ +207
EOF
|