NDB(6) NDB(6)
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
tuple 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(2) or indirectly using ndb/cs and ndb/dns (see ndb(8)).
Both ndb/cs and the routine ndbipinfo impose 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 it's
ip and ipmask attributes. If the ipmask is missing, the
relevant Class A, B or C one is used. The network is sub-
netted if one or more ipsubmask's are specified. A search
for an attribute associated with a network or host starts at
the top-level Class A, B, or C network and works it's way
down to the specific entry. The attribute/value chosen is
the one lowest down in the search, i.e, closest to the host.
For example, consider at the following entries:
ipnet=murray-hill ip=135.104.0.0 ipmask=255.255.0.0
NDB(6) NDB(6)
ipsubmask=255.255.255.0
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. If one were to search for anna's
NTP and SMTP servers, one would get oncore.cs.bell-labs.com
and smtp2.cs.bell-labs.com respectively.
Ndb/cs can be made to perform such network aware searches by
using metanames in the dialstring. A metaname is a $ fol-
lowed by an attribute name. Ndb/cs looks up the attribute
relative to the system it is running on. Thus, with the
above example, if a program called
dial("tcp!$smtp!smtp", 0, 0, 0);
the dial would connect to the SMTP port of
smtp2.cs.bell-labs.com.
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
ipsubmask Internet network mask of this network's subnets
ipgw Internet gateway
auth authentication server to be used
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. The pair
proto=il is needed by cs (see ndb(8)) in tuples
for hosts that support the IL protocol
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)
NDB(6) NDB(6)
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)
The file /lib/ndb/auth is used during authentication to
decide who has the power to `speak for' other users; see
auth(6).
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
/lib/ndb/local
first database file searched
SEE ALSO
dial(2), ndb(2), ndb(8), dhcpd(8), ipconfig(8), con(1)