.TH NDB 8
.SH NAME
query, ipquery, mkhash, mkdb, mkhosts, cs, csquery, dns, dnstcp, dnsquery, dnsdebug, inform \- network database
.SH SYNOPSIS
.B ndb/query
[
.B -am
] [
.B -f
.I dbfile
]
.I "attr value"
[
.I rattr
.\" [
.\" .I reps
.\" ]
]
.br
.B ndb/ipquery
.I "attr value"
.I rattr...
.br
.B ndb/mkhash
.I "file attr"
.br
.B ndb/mkdb
.br
.B ndb/mkhosts
[
.I domain
[
.I dbfile
] ]
.br
.B ndb/cs
[
.B -4n
] [
.B -f
.I dbfile
] [
.B -x
.I netmtpt
]
.br
.B ndb/csquery
[
.B -s
]
[
.I server
[
.I addr...
]
]
.br
.B ndb/dns
[
.B -norRs
] [
.B -a
.I maxage
] [
.B -f
.I dbfile
] [
.B -N
.I target
] [
.B -x
.I netmtpt
] [
.B -z
.I program
]
.br
.B ndb/dnstcp
[
.B -rR
] [
.B -f
.I dbfile
] [
.B -x
.I netmtpt
] [
.I conn-dir
]
.br
.B ndb/dnsquery
.br
.B ndb/dnsdebug
[
.B -rx
] [
.B -f
.I dbfile
] [ [
.BI @ server
]
.I domain-name
[
.I type
] ]
.br
.B ndb/inform
[
.B -x
.I netmtpt
]
.SH DESCRIPTION
The network database holds administrative information used by
network programs such as
.IR dhcpd (8),
.IR ipconfig (8),
.IR con (1),
etc.
.PP
.I Ndb/query
searches the database
.I dbfile
.RB ( /lib/ndb/local
by default)
for an attribute of type
.I attr
and value
.IR value .
If
.I rattr
is not specified, all entries matched by the search are printed.
If
.I rattr
is specified, the value of the first pair with attribute
.I rattr
of all the matched entries normally is printed.
Under
.B -m
and
.IR rattr ,
the values of all pairs with a
.I rattr
attribute within the first matching entry are printed.
Under
.B -a
and
.IR rattr ,
all values of pairs with a
.I rattr
attribute within all entries are printed.
.PP
.I Ndb/ipquery
uses
.I ndbipinfo
(see
.IR ndb (2))
to search for the values of the attributes
.I rattr
corresponding to the system
with entries of attribute type
.I attr
and
value
.IR value .
.PP
.I Ndb/inform
sends an RFC2136 DNS
.I inform
packet to a nameserver to associate the host's IPv4 address with its DNS name.
This is required if the domain's nameserver is
a Microsoft Windows Active Directory controller.
The host's domain name will be sent to the AD controller unless 
a tuple of the form
.BI inform= xxx
is found in the host's
.I ndb
entry.
.SS "Database maintenance"
.I Ndb/mkhash
creates a hash file for all entries with attribute
.I attr
in database file
.IR file .
The hash files are used by
.I ndb/query
and by the ndb library routines.
.PP
.I Ndb/mkdb
is used in concert with
.IR awk (1)
scripts to convert
uucp systems files and IP host files
into database files.
It is very specific to the situation at Murray Hill.
.PP
When the database files change underfoot,
.I ndb/cs
and
.I ndb/dns
track them properly.  Nonetheless, to keep the database searches efficient
it is necessary to run
.I ndb/mkhash
whenever the files are modified.
It may be profitable to control this by a frequent
.IR cron (8)
job.
.PP
.I Ndb/mkhosts
generates a BSD style
.BR hosts ,
.BR hosts.txt ,
and
.B hosts.equiv
files from an ndb data base file specified on the
command line (default
.BR /lib/ndb/local ).
For local reasons the files are called
.BR hosts.1127 ,
.BR astro.txt ,
and
.BR hosts.equiv .
.SS "Connection service"
.I Ndb/cs
is a server used by
.IR dial (2)
to translate network names.
It is started at boot time.
It finds out what networks are configured
by looking for
.B /net/*/clone
when it starts.
It can also be told about networks by writing to
.B /net/cs
a message of the form:
.IP
.B "add net1 net2 ..."
.PP
.I Ndb/cs
also sets the system name in
.B /dev/sysname
if it can figure it out.
The options are:
.TF -n
.TP
.B -4
Only look up IPv4 addresses (A records) when consulting DNS.
The default is to also look up v6 addresses (AAAA records).
Writing
.L ipv6
to
.B /net/cs
will toggle IP v6 look-ups.
.TP
.B -f
supplies the name of the data base file to use,
default
.BR /lib/ndb/local .
.TP
.B -n
causes cs to do nothing but set the system name.
.TP
.B -x
specifies the mount point of the
network.
.PD
.PP
.I Ndb/csquery
queries
.I ndb/cs
to see how it resolves addresses.
.I Ndb/csquery
prompts for addresses and prints what
.I ndb/cs
returns.
.I Server
defaults to
.BR /net/cs .
If any
.I addrs
are specified,
.I ndb/csquery
prints their translations and immediately exits.
The exit status will be nil only if all addresses
were successfully translated.
The
.B -s
flag sets exit status without printing any results.
.br
.ne 4
.SS "Domain name service"
.I Ndb/dns
serves
.I ndb/cs
and remote systems by translating Internet domain names.
.I Ndb/dns
is started at boot time.
By default
.I dns
serves only requests written to
.BR /net/dns .
Programs must
.I seek
to offset 0 before reading or writing
.B /net/dns
or
.BR /net/cs .
The options are:
.TF -n
.TP
.B -a
sets the maximum time in seconds that an unreferenced
domain name will remain cached.
The default is one hour (3600).
.TP
.B -f
supplies the name of the data base file to use,
default
.BR /lib/ndb/local .
.TP
.B -n
whenever a DNS zone that we serve changes, send UDP NOTIFY
messages to any dns slaves for that zone
(see the
.L dnsslave
attribute below).
.TP
.B -N
sets the goal for the number of domain names cached to
.I target
rather than the default of 8,000.
.TP
.B -o
used with
.BR -s ,
.B -o
causes
.I dns
to assume that it straddles inside and outside networks
and that the outside network is mounted on
.BR /net.alt .
Queries for inside addresses will be sent via
.B /net/udp
(or
.B /net/tcp
in response to truncated replies)
and those for outside addresses via
.B /net.alt/udp
(or
.BR /net.alt/tcp ).
This makes
.I dns
suitable for serving non-Plan-9 systems in an organization with
firewalls, DNS proxies, etc.,
particularly if they don't work very well.
See `Straddling Server' below for details.
.TP
.B -r
act as a resolver only:
send `recursive' queries, asking the other servers
to complete lookups.
If present,
.B /env/DNSSERVER
must be a space-separated list of such DNS servers' IP addresses,
otherwise optional
.IR ndb (6)
.B dns
attributes name DNS servers to forward queries to.
.TP
.B -R
ignore the `recursive' bit on incoming requests.
Do not complete lookups on behalf of remote systems.
.TP
.B -s
also answer domain requests sent to UDP port 53.
.TP
.B -x
specifies the mount point of the
network.
.TP
.B -z
whenever we receive a UDP NOTIFY message, run
.I program
with the domain name of the area as its argument.
.PD
.PP
When the
.B -r
option is specified, the servers used come from the
.I dns
attribute in the database.  For example, to specify a set of dns servers that
will resolve requests for systems on the network
.IR mh-net :
.IP
.EX
ipnet=mh-net ip=135.104.0.0 ipmask=255.255.0.0
	dns=ns1.cs.bell-labs.com
	dns=ns2.cs.bell-labs.com
dom=ns1.cs.bell-labs.com ip=135.104.1.11
dom=ns2.cs.bell-labs.com ip=135.104.1.12
.EE
.LP
The server for a domain is indicated by a database entry containing
both a
.I dom
and a
.I ns
attribute.
.IP
.EX
dom=
	ns=A.ROOT-SERVERS.NET
	ns=B.ROOT-SERVERS.NET
	ns=C.ROOT-SERVERS.NET
dom=A.ROOT-SERVERS.NET ip=198.41.0.4
dom=B.ROOT-SERVERS.NET ip=128.9.0.107
dom=C.ROOT-SERVERS.NET ip=192.33.4.12
.EE
.LP
The last three lines provide a mapping for the
server names to their ip addresses.  This is only
a hint and will be superseded from whatever is learned
from servers owning the domain.
.SS "Authoritative Name Servers"
You can also serve a subtree of the domain name space from the local
database.  You indicate subtrees that you would like to serve by adding an
.B soa=
attribute to the root entry.
For example, the Bell Labs CS research domain is:
.IP
.EX
dom=cs.bell-labs.com soa=
	refresh=3600 ttl=3600
	ns=plan9.bell-labs.com
	ns=ns1.cs.bell-labs.com
	ns=ns2.cs.bell-labs.com
	mb=presotto@plan9.bell-labs.com
	mx=mail.research.bell-labs.com pref=20
	mx=plan9.bell-labs.com pref=10
	dnsslave=nslocum.cs.bell-labs.com
	dnsslave=vex.cs.bell-labs.com
.EE
.LP
Here, the
.B mb
entry is the mail address of the person responsible for the
domain (default
.BR postmaster ).
The
.B mx
entries list mail exchangers for the domain name and
.B refresh
and
.B ttl
define the area refresh interval and the minimum TTL for
records in this domain.
The
.B dnsslave
entries specify slave DNS servers that should be notified
when the domain changes.  The notification also requires
the
.B -n
flag.
.
.SS "Reverse Domains"
You can also serve reverse lookups (returning the name that
goes with an IP address) by adding an
.B soa=
attribute to the entry defining the root of the reverse space.
.PP
For example, to provide reverse lookup for all addresses in
starting with
.L 135.104
or
.LR fd00:: ,
.I ndb
must contain a record like:
.IP
.EX
dom=104.135.in-addr.arpa soa=
	dom=d.f.ip6.arpa soa=	# special case, rfc 4193
	refresh=3600 ttl=3600
	ns=plan9.bell-labs.com
	ns=ns1.cs.bell-labs.com
	ns=ns2.cs.bell-labs.com
.EE
.LP
Notice the form of the reverse address.
For IPv4, it's the bytes of the address range you are serving reversed
and expressed in decimal, and with
.L .in-addr.arpa
appended.
For IPv6, it's the nibbles (4-bit fields) of the address range you are serving
reversed and expressed in hexadecimal, and with
.L .ip6.arpa
appended.
These are the standard forms for a domain name in a PTR record.
.PP
If such an
.B soa
entry exists in the database, reverse addresses will
automatically be generated from any IP addresses in the database
that are under this root.  For example
.IP
.EX
dom=ns1.cs.bell-labs.com ip=135.104.1.11
.EE
.LP
will automatically create both forward and reverse entries for
.BR ns1.cs.bell-labs.com .
Unlike other DNS servers, there's no way to generate
inconsistent forward and reverse entries.
.SS "Classless reverse delegation"
Following RFC 2317, it is possible to serve reverse DNS data
for IPv4 subnets smaller than /24.
Declare the non-/24 subnet, the reverse domain and the individual systems.
.PP
For example,
this is how to serve RFC-2317
.B ptr
records for the subnet
.LR 65.14.39.128/123 .
.IP
.EX
ipnet=our-t1 ip=65.14.39.128 ipmask=/123
dom=128.39.14.65.in-addr.arpa soa=
	refresh=3600 ttl=3600
	ns=ns1.our-domain.com
	ns=ns2.our-domain.com
ip=65.14.39.129 dom=router.our-domain.com
.EE
.
.SS "Delegating Name Service Authority"
Delegation of a further subtree to another set of name servers
is indicated by an
.B soa=delegated
attribute.
.IP
.EX
dom=bignose.cs.research.bell-labs.com
	soa=delegated
	ns=anna.cs.research.bell-labs.com
	ns=dj.cs.research.bell-labs.com
.EE
.LP
Nameservers within the delegated domain (as in this example)
must have their IP addresses listed elsewhere in
.I ndb
files.
.
.SS "Wildcards, MX and CNAME records"
Wild-carded domain names can also be used.
For example, to specify a mail forwarder for all Bell Labs research systems:
.IP
.EX
dom=*.research.bell-labs.com
	mx=research.bell-labs.com
.EE
.LP
`Cname' aliases may be established by adding a
.B cname
attribute giving the real domain name;
the name attached to the
.B dom
attribute is the alias.
`Cname' aliases are severely restricted;
the aliases may have no other attributes than
.B dom
and are daily further restricted in their use by new RFCs.
.IP
.EX
cname=anna.cs.bell-labs.com dom=www.cs.bell-labs.com
.EE
.PP
makes
.BI www. ...
a synonym for the canonical name
.BI anna. ... .
.SS "Straddling Server"
Many companies have an inside network
protected from outside access with firewalls.
They usually provide internal `root' DNS servers
(of varying reliability and correctness)
that serve internal domains and pass on DNS queries for
outside domains to the outside, relaying the results
back and caching them for future use.
Some companies don't even let DNS queries nor replies through
their firewalls at all, in either direction.
.PP
In such a situation, running
.B "dns -so"
on a machine that imports access to the outside network via
.B /net.alt
from a machine that straddles the firewalls,
or that straddles the firewalls itself,
will let internal machines query such a machine
and receive answers from outside nameservers for outside addresses
and inside nameservers for inside addresses, giving the appearance
of a unified domain name space,
while bypassing the corporate DNS proxies or firewalls.
This is different from running
.B "dns -s"
and
.B "dns -sRx /net.alt -f /lib/ndb/external"
on the same machine,
which keeps the inside and outside namespaces entirely separate.
.PP
Under
.BR -o ,
several
.I sys
names are significant:
.BR inside-dom ,
.BR inside-ns ,
and
.BR outside-ns .
.I Inside-dom
should contain a series of
.B dom
pairs naming domains internal to the organization.
.I Inside-ns
should contain a series of
.B ip
pairs naming the internal DNS `root' servers.
.I Outside-ns
should contain a series of
.B ip
pairs naming the external DNS servers to consult.
.SS "Zone Transfers and TCP"
.I Dnstcp
is invoked,
usually from
.BR /rc/bin/service/tcp53 ,
to answer DNS queries with long answers via TCP,
notably to transfer a zone within the database
.I dbfile
(default
.BR /lib/ndb/local )
to its invoker on the network at
.I netmtpt
(default
.BR /net ).
Standard input will be read for DNS requests and the DNS answers
will appear on standard output.
Recursion is disabled by
.BR -R ;
acting as a pure resolver is enabled by
.BR -r .
If
.I conn-dir
is provided, it is assumed to be a directory within
.IB netmtpt /tcp
and is used to find the caller's address.
.SS "DNS Queries and Debugging"
.I Ndb/dnsquery
can be used to query
.I ndb/dns
to see how it resolves requests.
.I Ndb/dnsquery
prompts for commands of the form
.IP
.I "domain-name request-type"
.LP
where
.I request-type
can be
.BR ip ,
.BR ipv6 ,
.BR mx ,
.BR ns ,
.BR cname ,
.BR ptr ....
In the case of the inverse query type,
.BR ptr ,
.I dnsquery
will reverse the ip address and tack on the
.B .in-addr.arpa
if necessary.
.PP
.I Ndb/dnsdebug
is like
.I ndb/dnsquery
but bypasses the local server.
It communicates via UDP (and sometimes TCP) with the domain name servers
in the same way that the local resolver would and displays
all packets received.
The query can be specified on the command line or
can be prompted for.
The queries look like those of
.I ndb/dnsquery
with one addition.
.I Ndb/dnsdebug
can be directed to query a particular name server by
the command
.BI @ name-server\f1.
From that point on, all queries go to that name server
rather than being resolved by
.IR dnsdebug .
The
.B @
command returns query resolution to
.IR dnsdebug .
Finally, any command preceded by a
.BI @ name-server
sets the name server only for that command.
.PP
Normally
.I dnsdebug
uses the
.B /net
interface and the database file
.BR /lib/ndb/local.
The
.B -f
option supplies the name of the data base file to use.
The
.B -r
option is the same as for
.IR ndb/dns .
The
.B -x
option directs
.I dnsdebug
to use the
.B /net.alt
interface and
.B /lib/ndb/external
database file.
.SH EXAMPLES
Look up
.B helix
in
.IR ndb .
.IP
.EX
% ndb/query sys helix
sys=helix dom=helix.research.bell-labs.com bootf=/mips/9powerboot
	ip=135.104.117.31 ether=080069020427
.EE
.br
.ne 8
.LP
Look up
.B plan9.bell-labs.com
and its IP address in the DNS.
.IP
.EX
% ndb/dnsquery
> plan9.bell-labs.com ip
plan9.bell-labs.com ip	135.104.24.16
> 135.104.24.16 ptr
16.24.104.135.in-addr.arpa ptr	plan9.bell-labs.com
16.24.104.135.in-addr.arpa ptr	ampl.com
>
.EE
.LP
Print the names of all PCs that boot via PXE.
.IP
.EX
% ndb/query -a bootf /386/9boot sys
.EE
.SH FILES
.TF /lib/ndb/local.*xxx
.TP
.B /env/DNSSERVER
resolver's DNS servers' IP addresses.
.TP
.B /lib/ndb/local
first database file searched
.TP
.B /lib/ndb/local.*
hash files for
.B /lib/ndb/local
.TP
.B /srv/cs
service file for
.I ndb/cs
.TP
.B /net/cs
where
.B /srv/cs
gets mounted
.TP
.B /srv/dns
service file for
.I ndb/dns
.TP
.B /net/dns
where
.B /srv/dns
gets mounted
.SH SOURCE
.B /sys/src/cmd/ndb
.SH SEE ALSO
.IR ndb (2),
.IR ndb (6)
.SH BUGS
.I Ndb
databases are case-sensitive;
ethernet addresses must be in lower-case hexadecimal.