man(1) Manual page archive

     NDB(7)                                                     NDB(7)

          ndb - Network database

          The network database consists of files describing machines
          known to the local installation and machines known publicly.
          The files comprise multi-line tuples made up of
          attribute/value pairs of the form attr=value or sometimes
          just attr. Each line starting without white space starts a
          new tuple.  Lines starting with # are comments.

          The file /lib/ndb/local is the root of the database.  Other
          files are included in the database if a tuple with an
          attribute-value pair of attribute database and no value
          exists in /lib/ndb/local.  Within the database tuple, each
          pair with attribute file identifies a file to be included in
          the database.  The files are searched in the order they
          appear.  For example:


          declares the database to be composed of the three files
          /lib/ndb/common, /lib/ndb/local, and /lib/ndb/global.  By
          default, /lib/ndb/local is searched before the others.  How-
          ever, /lib/ndb/local may be included in the database to
          redefine its ordering.

          Within tuples, pairs on the same line bind tighter than
          pairs on different lines.

          Programs search the database directly using the routines in
          ndb(3). The routine ndbipinfo imposes structure on the oth-
          erwise flat database by using knowledge specific to the net-
          work.  The internet is made up of networks which can be sub-
          netted multiple times.  A network must have an ipnet
          attribute and is uniquely identified by the values of its ip
          and ipmask attributes.  If the ipmask is missing, the rele-
          vant Class A, B or C one is used.

          A search for an attribute associated with a network or host
          starts at the lowest level, the entry for the host or net-
          work itself, and works its way up, bit by bit, looking at
          entries for nets/subnets that include the network or host.
          The search ends when the attribute is found.  For example,
          consider at the following entries:

               ipnet=murray-hill ip= ipmask=

     NDB(7)                                                     NDB(7)

               ipnet=plan9 ip= ipmask=
               ip= sys=anna

          Here anna is on the subnet plan9 which is in turn on the
          class B net murray-hill.  Assume that we're searching for
          anna's NTP and SMTP servers.  The search starts by looking
          for an entry with sys=anna.  We find the anna entry.  Since
          it has an pair, we're done look-
          ing for that attribute.  To fulfill the NTP request, we con-
          tinue by looking for networks that include anna's IP
          address.  We lop off the right most one bit from anna's
          address and look for an ipnet= entry with ip=
          Not finding one, we drop another bit and look for an ipnet=
          entry with ip=  There is such an entry and it
          has the pair,, ending our

          A number of attributes are meaningful to programs and thus
          reserved.  They are:

          sys         system name
          dom         Internet domain name
          ip          Internet address
          ether       Ethernet address
          bootf       file to download for initial bootstrap
          ipnet       Internet network name
          ipmask      Internet network mask
          ipgw        Internet gateway
          auth        authentication server to be used
          authdom     authentication domain.  Plan 9 supports multiple
                      authentication domains.  To specify an authenti-
                      cation server for a particular domain, add a
                      tuple containing both auth and authdom
                      attributes and values.
          fs          file server to be used
          tcp         a TCP service name
          udp         a UDP service name
          il          an IL service name
          port        a TCP, UDP, or IL port number
          restricted  a TCP service that can be called only by ports
                      numbered less that 1024
          proto       a protocol supported by a host.
          dnsdomain   a domain name that ndb/dns adds onto any
                      unrooted names when doing a search There may be
                      multiple dnsdomain pairs.
          dns         a DNS server to use (for DNS and DHCP)
          ntp         an NTP server to use (for DHCP)

     NDB(7)                                                     NDB(7)

          smtp        an SMTP server to use (for DHCP)
          time        a time server to use (for DHCP)
          wins        a Windows name server (for DHCP)
          mx          mail exchanger (for DNS and DHCP)
          soa         start of area (for DNS)

          A tuple for the CPU server, spindle.

          sys = spindle
               ip= ether=080069020677

          Entries for the network mh-astro-net and its subnets.

          ipnet=mh-astro-net ip= ipmask=
          ipnet=unix-room ip=
          ipnet=third-floor ip=

          Mappings between TCP service names and port numbers.

          tcp=sysmon     port=401
          tcp=rexec      port=512   restricted
          tcp=9fs        port=564

               first database file searched

          ndb(1), ndb(3)