grepcidr is a
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.
grepcidr has endless uses in network software, including: mail filtering and processing, network security, log analysis, and many custom applications.
For detailed instructions and examples, please see the README file or man page. A couple examples of usage:
grepcidr 2001:db8::/32 logfile grepcidr 18.104.22.168/19 access.log
Install grepcidr with your package manager:
sudo apt install grepcidr