BPF example
1 (000) ldh [12] 2 (001) jeq #0x86dd jt 2 jf 6 #check ipv6 or not 3 (002) ldb [20] 4 (003) jeq #0x6 jt 4 jf 15 #check tcp or not 5 (004) ldh [56] 6 (005) jeq #0x1b9e jt 14 jf 15 #check port 7070(0x1b9e) or not 7 (006) jeq #0x800 jt 7 jf 15 #check ipv4 or not 8 (007) ldb [23] 9 (008) jeq #0x6 jt 9 jf 15 #check tcp or not 10 (009) ldh [20] 11 (010) jset #0x1fff jt 15 jf 11 #check IP fragmentation or not 12 (011) ldxb 4*([14]&0xf) 13 (012) ldh [x + 16] #find dest port in tcp 14 (013) jeq #0x1b9e jt 14 jf 15 #check port 7070(0x1b9e) or not 15 (014) ret #262144 #meet the requirement 16 (015) ret #0 #deny