Section 8 · System administration
nfbpf_compile.8
Package: iptables-utils
NFBPF_COMPILE
NAME
SYNOPSIS
DESCRIPTION
OPTIONS
EXIT STATUS
EXAMPLE
SEE ALSO
NAME
nfbpf_compile — generate bytecode for use with xt_bpf
SYNOPSIS
nfbpf_compile [ LLTYPE ] PROGRAM
LLTYPE := { EN10MB | RAW | SLIP | … }
DESCRIPTION
The nfbpf_compile utility aids in generating BPF byte code suitable for passing to the iptables bpf match.
OPTIONS
| LLTYPE | Link-layer header type to operate on. This is a name as defined in <pcap/dlt.h> but with the leading DLT_ prefix stripped. For use with iptables, RAW should be the right choice (it’s also the default if not specified). |
PROGRAM
The BPF expression to compile, see pcap-filter(7) for a description of the language.
EXIT STATUS
The program returns 0 on success, 1 otherwise.
EXAMPLE
Match incoming TCP packets with size bigger than 100 bytes:
bpf=$(nfbpf_compile ’tcp and greater 100’)
iptables -A INPUT -m bpf —bytecode “$bpf” -j ACCEPT
The description of bpf match in iptables-extensions(8) lists a few more examples.
SEE ALSO
iptables-extensions(8), pcap-filter(7)