NDB(7)

💖 NAME 💖

okay bestie, welcome to NDB(7) — the manual page for ndb, aka the Network database, straight from the Miscellaneous Information Manual. This is literally the whole lore of how the network database files are put together. 🫶

✨ DESCRIPTION ✨

The network database is made of files that describe machines known to the local installation and machines known publicly. The files are built from multi-line tuples made up of attribute/value pairs of the form attr=value, or sometimes just attr. Each line that starts without white space starts a new tuple, and lines starting with # are comments. periodt.

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

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:

              database=
                   file=/lib/ndb/common
                   file=/lib/ndb/local
                   file=/lib/ndb/global

That 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. However, /lib/ndb/local may be included in the database to redefine its ordering.

Programs search the database directly using the routines in ndb(3). The routine ndbipinfo imposes structure on the otherwise flat database by using knowledge specific to the network. The internet is made up of networks which can be subnetted 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 relevant 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 network 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 these entries:

              ipnet=murray-hill ip=135.104.0.0 ipmask=255.255.0.0
                   dns=135.104.10.1
                   ntp=ntp.cs.bell-labs.com
              ipnet=plan9 ip=135.104.9.0 ipmask=255.255.255.0
                   ntp=oncore.cs.bell-labs.com
                   smtp=smtp1.cs.bell-labs.com
              ip=135.104.9.6 sys=anna dom=anna.cs.bell-labs.com
                   smtp=smtp2.cs.bell-labs.com

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 smtp=smtp2.cs.bell-labs.com pair, we’re done looking for that attribute. To fulfill the NTP request, we continue 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=135.104.9.4. Not finding one, we drop another bit and look for an ipnet= entry with ip=135.104.9.0. There is such an entry and it has the pair, ntp=oncore.cs.bell-labs.com, ending our search.

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

• sys — system name. main character identity.
• 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 authentication server for a particular domain, add a tuple containing both auth and authdom attributes and values. so specific, love that.
• 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. gatekept by port numbers, fr fr.
• 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).
• 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).

🎀 EXAMPLES 🎀

A tuple for the CPU server, spindle.

       sys = spindle
            dom=spindle.research.bell-labs.com
            bootf=/mips/9powerboot
            ip=135.104.117.32 ether=080069020677
            proto=il

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

       ipnet=mh-astro-net ip=135.104.0.0 ipmask=255.255.255.0
            fs=bootes.research.bell-labs.com
            ipgw=r70.research.bell-labs.com
            auth=p9auth.research.bell-labs.com
       ipnet=unix-room ip=135.104.117.0
            ipgw=135.104.117.1
       ipnet=third-floor ip=135.104.51.0
            ipgw=135.104.51.1

Mappings between TCP service names and port numbers.

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

📁 FILES 📁

• /ndb/local — first database file searched. the first stop on the database tour.

👀 SEE ALSO 👀

• ndb(1)
• ndb(3)

mwah 💋 — that’s the whole NDB(7) page, bestie. It comes from the Miscellaneous Information Manual, the footer is just NDB(7), and there’s no date stamped on it, so that’s the iconic original energy. 🫶