Created
May 26, 2019 16:40
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very useful for quick IPtables, don't want to lose it again
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/* | |
* BPF program compilation tool | |
* | |
* Generates decimal output, similar to `tcpdump -ddd ...`. | |
* Unlike tcpdump, will generate for any given link layer type. | |
* | |
* Written by Willem de Bruijn (willemb@google.com) | |
* Copyright Google, Inc. 2013 | |
* Licensed under the GNU General Public License version 2 (GPLv2) | |
*/ | |
#include <pcap.h> | |
#include <stdio.h> | |
int main(int argc, char **argv) | |
{ | |
struct bpf_program program; | |
struct bpf_insn *ins; | |
int i, dlt = DLT_RAW; | |
if (argc < 2 || argc > 3) { | |
fprintf(stderr, "Usage: %s [link] '<program>'\n\n" | |
" link is a pcap linklayer type:\n" | |
" one of EN10MB, RAW, SLIP, ...\n\n" | |
"Examples: %s RAW 'tcp and greater 100'\n" | |
" %s EN10MB 'ip proto 47'\n'", | |
argv[0], argv[0], argv[0]); | |
return 1; | |
} | |
if (argc == 3) { | |
dlt = pcap_datalink_name_to_val(argv[1]); | |
if (dlt == -1) { | |
fprintf(stderr, "Unknown datalinktype: %s\n", argv[1]); | |
return 1; | |
} | |
} | |
if (pcap_compile_nopcap(65535, dlt, &program, argv[argc - 1], 1, | |
PCAP_NETMASK_UNKNOWN)) { | |
fprintf(stderr, "Compilation error\n"); | |
return 1; | |
} | |
printf("%d,", program.bf_len); | |
ins = program.bf_insns; | |
for (i = 0; i < program.bf_len-1; ++ins, ++i) | |
printf("%u %u %u %u,", ins->code, ins->jt, ins->jf, ins->k); | |
printf("%u %u %u %u\n", ins->code, ins->jt, ins->jf, ins->k); | |
pcap_freecode(&program); | |
return 0; | |
} | |
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