walldns - a reverse DNS wall

       Normally walldns is set up by the walldns-conf(8) program.

       walldns runs chrooted in the directory specified by the $ROOT environment variable, under the uid and gid
       specified by the $UID and $GID environment variables.

       walldns listens for incoming UDP packets addressed to port 53  of  $IP.   It  does  not  listen  for  TCP
       queries.

walldns  is  a  reverse  DNS  wall.  It accepts iterative DNS queries for in-addr.arpa domains from hosts
       around the Internet, and supplies generic responses that avoid revealing local host information.

       For example, walldns provides a PTR record for 4.3.2.1.in-addr.arpa showing 4.3.2.1.in-addr.arpa  as  the
       name  of  IP  address  1.2.3.4,  and a matching A record showing 1.2.3.4 as the IP address of 4.3.2.1.in-addr.arpa.

walldns  rejects  inverse  queries,  non-Internet-class  queries, truncated packets, packets that contain
       anything other than a single question, queries for domains outside in-addr.arpa, and request types  other
       than A, PTR, and *.

       walldns does not include NS or SOA records with its responses.

       walldns uses TTLs slightly over one week.

       walldns - a reverse DNS wall

walldns-conf(8)

       http://cr.yp.to/djbdns.htmlwalldns(8)