IP Resolution with nmap
A question came to the nmap-dev mailing list regarding resolving IP Addresses in bulk. Doug replied with a command to do just that. I decided that it was handy to keep around but I wanted to clean it up a little, so I turned it into this:
nmap -sL $1 2>/dev/null | perl -ne 'print unless /^Host [\d.]+ /' | grep 'not scanned' | cut -d ' ' -f 2,3 | sed -e 's/\(.*\) (\(.*\))/\2 resolves to \1/'
Which leads to output similar to this:
198.133.219.10 resolves to fed.cisco.com
198.133.219.11 resolves to asp-web-sj-1.cisco.com
198.133.219.12 resolves to asp-web-sj-2.cisco.com
198.133.219.13 resolves to fedtst.cisco.com
198.133.219.14 resolves to www.netimpactstudy.com
198.133.219.15 resolves to deployx-sj.cisco.com
198.133.219.16 resolves to contact-sj1.cisco.com
198.133.219.17 resolves to scc-sj-1.cisco.com
198.133.219.18 resolves to scc-sj-2.cisco.com
198.133.219.19 resolves to scc-sj-3.cisco.com
198.133.219.20 resolves to jmckerna-test.cisco.com
198.133.219.21 resolves to events.cisco.com
198.133.219.22 resolves to bam-prod-1.cisco.com
198.133.219.23 resolves to redirect.cisco.com
198.133.219.25 resolves to www.cisco.com
198.133.219.26 resolves to partners.cisco.com