Crawl through ip address space getting DNS names.
Added to GitHub as I could not find another source for this great little program.
gcc ipcrawl.c -o ipcrawl
chmod -x ipcrawl
./ipcrawl -q -v -s -f
- first address in range to scan
- last address of range to scan
-f - log output to file
-s - seconds to wait between every 50 lookups
-q - quiet (no console output)
-v - verbose mode