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GREPCIDR(1)            DragonFly General Commands Manual           GREPCIDR(1)


NAME

       grepcidr -- Filter IPv4 and IPv6 addresses matching CIDR patterns


SYNOPSIS

       grepcidr [OPTIONS]  PATTERN [FILE...]

       grepcidr [OPTIONS]  [-e PATTERN | -f PATFILE]  [FILE...]


DESCRIPTION

       grepcidr can be used to filter a list of IP addresses against one or
       more Classless Inter-Domain Routing (CIDR) specifications.  As with
       grep, there are options to invert matching and load patterns from a
       file.  grepcidr is capable of efficiently processing large numbers of
       IPs and networks.


OPTIONS

       -V        Show software version

       -c        Display count of the matching lines, instead of showing the
                 lines

       -i        Inverse match, include lines without an IP, implies -v

       -s        Enforce strict alignment of CIDR mask; host portion must be
                 all zero

       -v        Invert the sense of matching, output lines with IPs that
                 don't match

       -x        Strict matching, only look at start of line

       -e        Specify individual IP or CIDR pattern(s) on command-line

       -f        Load individual IP or CIDR pattern(s) from file


USAGE NOTES

       PATTERN specified on the command line may contain multiple patterns
       separated by whitespace or commas. For long lists of network patterns,
       use -f to load a file where each line contains one pattern (can be IPv4
       or IPv6).  Blank lines and comments starting with # are ignored.

       Each IPv4 pattern, whether on command line or loaded from a file, may
       be:

       a.b.c.d/xy        (CIDR format)
       a.b.c.d-e.f.g.h   (IP range)
       a.b.c.d           (Single IP)

       And similarly for IPv6:

       a:b:c::/xyz       (CIDR format)
       a:b:c::           (Single IP)

       Dotted-decimal IPv4 format, or any legal IPv6 format is supported (see:
       man inet_pton).

       IP addresses that appear anywhere on the input line will be compared
       and matched against the patterns.  To be recognized, an IP (field) must
       end with terminating text.  An IPv4 field terminates upon anything
       other than alphanumeric or dot.  An IPv6 field terminates upon anything
       other than alphanumeric, dot, or colon.  This is to prevent accidental
       matching of ambiguous text such as host names containing reverse DNS.

       Use the -x option to do a strict parse without searching the whole
       line, and grepcidr will only look for the single IP at the start of the
       line.


EXAMPLES

       grepcidr -f ournetworks blacklist > abuse.log

       Find customers (CIDR ranges in file) that appear in blacklist

       grepcidr 2001:db8::/32 log.1 log.2

       Search for this IPv6 network inside two files

       grepcidr 127.0.0.0/8 iplog

       Searches for any localnet IP addresses inside the iplog file

       grepcidr "192.168.0.1-192.168.10.13" iplog

       Searches for IPs matching indicated range in the iplog file

       script | grepcidr -vf whitelist > blacklist

       Create a blacklist, with whitelisted networks removed (inverse)

       grepcidr -f list1 list2

       Cross-reference two lists, outputs IPs common to both lists


EXIT STATUS

       As with grep: the exit status is 0 if matching IPs are found, and 1 if
       not found.  If an error occurred the exit status is 2.


AUTHOR

       This software and manual page was written by Jem Berkes <jem@berkes.ca>
       based on the first man page and DocBook format contributed by Ryan
       Finnie.  Permission is granted to copy, distribute and/or modify this
       document under the terms of the GNU General Public License, Version 2
       or any later version published by the Free Software Foundation.


WEB SITE

       http://www.pc-tools.net/unix/grepcidr/


THANKS

       Sponsored in part by the Spamhaus Project, http://www.spamhaus.org/

       Thanks to John Levine <johnl@taugh.com> for sharing his alternative
       implementation.  I used a couple ideas from his code, such as portable
       128-bit numbers and support for multiple input files. However, John's
       version is quite different and represents a significant fork in the
       project.

       Thanks to Ryan Finnie <ryan@finnie.org> for his work on the Debian
       package.  I've adopted several of his changes including the Makefile,
       and the DocBook format which now is the source of the man page.  Thanks
       to Ryan for writing the first manual in DocBook format.

       Many thanks to Dick Wesseling <ftu@fi.uu.nl> who suggested an improved
       data structure format as well as binary search, to improve grepcidr
       performance.

                                                                   GREPCIDR(1)

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