NDB(7) NDB(7)
NAME
ndb - Network database
DESCRIPTION
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:
database=
file=/lib/ndb/common
file=/lib/ndb/local
file=/lib/ndb/global
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=135.104.0.0 ipmask=255.255.0.0
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NDB(7) NDB(7)
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 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=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
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)
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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)
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
/usr/local/plan9/ndb/local
first database file searched
SEE ALSO
ndb(1), ndb(3)
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