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NAME

       grepcidr — Filter IP addresses matching IPv4 CIDR/network specification

SYNOPSIS

       grepcidr [-V]  [-c]  [-v]  [-e pattern | -f file]

DESCRIPTION

       This manual page documents briefly the grepcidr command.

       This manual page was written for the Debian  distribution  because  the
       original program does not have a manual page.

       grepcidr  can  be  used to filter a list of IP addresses against one or
       more Classless Inter-Domain Routing (CIDR) specifications, or arbitrary
       networks specified by an address range. As with grep, there are options
       to invert matching and load patterns from a file.  grepcidr is  capable
       of  comparing thousands or even millions of IPs to networks with little
       memory usage and in reasonable computation time.

OPTIONS

       -V        Show software version

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

       -v        Invert  the  sense  of  matching,  to  select non-matching IP
                 addresses

       -e        Specify pattern(s) on command-line

       -f        Obtain CIDR and range pattern(s) from file

EXAMPLES

       grepcidr -f ournetworks blocklist > abuse.log

       Find our customers that show up in blocklists

       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

AUTHOR

       This manual page was written by Ryan  Finnie  ryan@finnie.org  for  the
       Debian  system  (but  may be used by others).  Permission is granted to
       copy, distribute and/or modify this document under the terms of the GNU
       General  Public  License,  Version 2 any later version published by the
       Free Software Foundation.

       On Debian systems, the complete text of the GNU General Public  License
       can be found in /usr/share/common-licenses/GPL.