351 lines
6.6 KiB
Plaintext
351 lines
6.6 KiB
Plaintext
.TH NDB 6
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.SH NAME
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ndb \- Network database
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.SH DESCRIPTION
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.PP
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The network database consists of files
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describing machines known to the local
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installation and machines known publicly.
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The files comprise multi-line tuples made up of
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attribute/value pairs of the form
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.IB attr = value
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or sometimes just
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.IR attr .
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Each line starting without white space starts a new tuple.
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Lines starting with
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.B #
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are comments.
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.PP
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The file
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.B /lib/ndb/local
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is the root of the database.
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Other files are included in the
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database if a tuple with an
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attribute-value pair of attribute
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.B database
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and no value exists in
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.BR /lib/ndb/local
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.
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Within the
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.B database
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tuple,
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each pair with attribute
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.B file
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identifies a file to be included in the database. The files are searched
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in the order they appear.
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For example:
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.IP
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.EX
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database=
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file=/lib/ndb/common
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file=/lib/ndb/local
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file=/lib/ndb/global
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.EE
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.PP
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declares the database to be composed of the three files
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.BR /lib/ndb/common ,
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.BR /lib/ndb/local ,
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and
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.BR /lib/ndb/global .
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By default,
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.B /lib/ndb/local
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is searched before the others.
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However,
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.B /lib/ndb/local
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may be included in the
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.B database
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to redefine its ordering.
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.PP
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Within tuples, pairs on the same line bind tighter than
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pairs on different lines.
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.PP
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Programs search the database directly using the routines in
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.IR ndb (2)
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or indirectly using
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.B ndb/cs
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and
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.B ndb/dns
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(see
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.IR ndb (8)).
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Both
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.B ndb/cs
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and the routine
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.I ndbipinfo
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impose structure on the otherwise flat database by using
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knowledge specific to the network.
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The internet is made up of networks which can be subnetted
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multiple times. A network must have an
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.B ipnet
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attribute and is uniquely identified by the values of its
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.B ip
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and
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.B ipmask
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attributes. If the
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.B ipmask
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is missing, the relevant Class A, B or C one is used.
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.LP
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A search for an attribute associated with a network or host starts
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at the lowest level, the entry for the host or network itself,
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and works its way up, bit by bit, looking at entries for nets/subnets
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that include the network or host. The search ends when the attribute
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is found.
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For example, consider the following entries:
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.IP
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.EX
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ipnet=murray-hill ip=135.104.0.0 ipmask=255.255.0.0
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dns=135.104.10.1
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ntp=ntp.cs.bell-labs.com
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ipnet=plan9 ip=135.104.9.0 ipmask=255.255.255.0
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ntp=oncore.cs.bell-labs.com
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smtp=smtp1.cs.bell-labs.com
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ip=135.104.9.6 sys=anna dom=anna.cs.bell-labs.com
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smtp=smtp2.cs.bell-labs.com
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.EE
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.LP
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Here
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.B anna
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is on the subnet
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.B plan9
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which is in turn on the class B net
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.BR murray-hill .
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Assume that we're searching for
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.BR anna 's
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.B NTP
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and
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.B SMTP
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servers.
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The search starts by looking for an entry with
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.BR sys=anna .
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We find the anna entry. Since it has an
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.B smtp=smtp2.cs.bell-labs.com
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pair,
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we're done looking for that attribute.
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To fulfill the NTP request, we continue by looking for networks
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that include anna's IP address.
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We lop off the right most one bit from anna's address and
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look for an
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.B ipnet=
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entry with
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.BR ip=135.104.9.4 .
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Not finding one, we drop another bit and look for an
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.B ipnet=
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entry with
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.BR ip=135.104.9.0 .
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There is
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such an entry and it has the pair,
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.BR ntp=oncore.cs.bell-labs.com ,
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ending our search.
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.PP
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.I Ndb/cs
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can be made to perform such network aware
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searches by using metanames in the dialstring.
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A metaname is a
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.I $
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followed by an attribute name.
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.I Ndb/cs
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looks up the attribute relative to the system it is running
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on. Thus, with the above example, if a program called
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.IP
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.EX
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dial("tcp!$smtp!smtp", 0, 0, 0);
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.EE
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.LP
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the dial would connect to the SMTP port of
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.BR smtp2.cs.bell-labs.com .
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.PP
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A number of attributes are meaningful to programs and thus
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reserved.
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They are:
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.TF dnsdomain
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.TP
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.B sys
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system name (a short name)
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.TP
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.B dom
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Internet fully-qualified domain name
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.TP
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.B ip
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Internet address,
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v4 or v6.
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.TP
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.B ipv6
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IPv6 Internet address.
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For DNS, an
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.L AAAA
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record.
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.TP
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.B ether
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Ethernet address
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(must be lower-case hexadecimal).
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Beware that for machines with multiple
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.B ether
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attributes,
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.I dhcpd
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may expect requests to come from the address in the first
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.B ether
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attribute.
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.TP
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.B bootf
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file to download for initial bootstrap;
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.B /386/9bootpxe
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to boot a PC via PXE.
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.TP
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.B ipnet
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Internet network name
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.TP
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.B ipmask
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Internet network mask
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.TP
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.B ipgw
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Internet gateway
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.TP
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.B auth
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authentication server to be used
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.TP
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.B authdom
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authentication domain. Plan 9 supports multiple authentication
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domains. To specify an authentication server for a particular domain,
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add a tuple containing both
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.B auth
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and
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.B authdom
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attributes and values.
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.TP
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.B fs
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file server to be used
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.TP
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.B tcp
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a TCP service name
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.TP
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.B udp
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a UDP service name
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.TP
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.B port
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a TCP or UDP port number
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.TP
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.B restricted
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a TCP service that can be called only by ports numbered
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less that 1024
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.TP
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.B proto
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a protocol supported by a host.
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The pair
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.B proto=il
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was needed by
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.I cs
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(see
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.IR ndb (8))
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in tuples for hosts that supported the IL protocol
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.TP
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.B dnsdomain
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a domain name that
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.I ndb/dns
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adds onto any unrooted names when doing a search.
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There may be multiple
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.B dnsdomain
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pairs.
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.TP
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.B dns
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a DNS server to use (for DNS and DHCP)
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.TP
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.B ntp
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an NTP server to use (for DHCP)
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.TP
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.B smtp
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an SMTP server to use (for DHCP)
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.TP
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.B time
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a time server to use (for DHCP)
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.TP
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.B wins
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a Windows name server (for DHCP)
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.TP
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.B mx
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mail exchanger (for DNS and DHCP);
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also
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.BR pref .
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.TP
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.B srv
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service location (for DNS);
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also
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.BR pri ,
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.B weight
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and
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.BR port .
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.TP
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.B soa
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start of area (for DNS)
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.PD
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.PP
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.I Cs
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defers to
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.I dns
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to translate dotted names to IP addresses,
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only consulting the database files if
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.I dns
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cannot translate the name.
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.PP
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.I Cs
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allows network entries with
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.B sys
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and
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.B dom
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attributes but no
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.B ip
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attribute.
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Searches for the system name are resolved
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by looking up the domain name with
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.IR dns .
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.PP
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The file
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.B /lib/ndb/auth
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is used during authentication to decide who has the power to `speak for' other
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users; see
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.IR authsrv (6).
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.SH EXAMPLES
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.LP
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A tuple for the CPU server, spindle.
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.LP
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.EX
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sys=spindle
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dom=spindle.research.bell-labs.com
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bootf=/mips/9powerboot
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ip=135.104.117.32 ether=080069020677
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.EE
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.LP
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Entries for the network
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.B mh-astro-net
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and its subnets.
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.LP
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.EX
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ipnet=mh-astro-net ip=135.104.0.0 ipmask=255.255.255.0
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fs=bootes.research.bell-labs.com
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ipgw=r70.research.bell-labs.com
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auth=p9auth.research.bell-labs.com
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ipnet=unix-room ip=135.104.117.0
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ipgw=135.104.117.1
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ipnet=third-floor ip=135.104.51.0
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ipgw=135.104.51.1
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.EE
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.LP
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Mappings between TCP service names and port numbers.
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.LP
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.EX
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.ta \w'\fLtcp=sysmonxxxxx'u \w'\fLtcp=sysmonxxxxxport=512xxx'u
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tcp=sysmon port=401
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tcp=rexec port=512 restricted
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tcp=9fs port=564
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.EE
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.SH FILES
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.TF /lib/ndb/local
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.TP
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.B /lib/ndb/local
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first database file searched
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.SH "SEE ALSO"
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.IR con (1),
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.IR dial (2),
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.IR ndb (2),
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.IR booting (8),
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.IR dhcpd (8),
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.IR ipconfig (8),
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.IR ndb (8)
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