Entering the text into the search performs a <b>keyword search</b> - the search string is matched against every aspect of the host.
To refine the search, you can use <b>operators</b> to search only specific fields within a host. Most operators have a short form, listed.
<b>target: (t:)</b> - User-supplied target, or a rDNS result.
<b>os:</b> - All OS-related fields.
<b>open: (op:)</b> - Open ports discovered in a scan.
<b>closed: (cp:)</b> - Closed ports discovered in a scan.
<b>filtered: (fp:)</b> - Filtered ports discovered in scan.
<b>unfiltered: (ufp:)</b> - Unfiltered ports found in a scan (using, for example, an ACK scan).
<b>open|filtered: (ofp:)</b> - Ports in the "open|filtered" state.
<b>closed|filtered: (cfp:)</b> - Ports in the "closed|filtered" state.
<b>service: (s:)</b> - All service-related fields.
<b>inroute: (ir:)</b> - Matches a router in the scan's traceroute output.