fns_dns(5)
NAME
fns_dns - overview of FNS over DNS implementation
DESCRIPTION
Federated Naming Service (FNS) provides a method for
federating multiple naming services under a single, simple
interface for the basic naming operations. One of the naming
services supported by FNS is the Internet Domain Name Sys-
tem, or DNS (see in.named(1M)). DNS is a hierarchical col-
lection of name servers that provide the Internet community
with host and domain name resolution. FNS uses DNS to name
entities globally. Names can be constructed for any enter-
prise that is accessible on the Internet; consequently,
names can also be constructed for objects exported by these
enterprises.
FNS provides the XFN interface for performing naming resolu-
tion on DNS domains and hosts. In addition, enterprise
namespaces such as those served by NIS+ and NIS can be
federated with DNS by adding TXT records to DNS. To
federate an NIS+ or NIS namespace under DNS, you first
obtain the root reference for the NIS+ hierarchy or NIS
domain. This reference is referred to as the next naming
system reference because it refers to the next naming sys-
tem beneath the DNS domain. This reference contains informa-
tion about how to communicate with the NIS+ or NIS servers
and has the following format:
<domainname> <server name> [ <server address> ]
where <domainname> is the fully qualified domain name.
Notice that NIS+ and NIS have slightly different syntaxes
for domain names. For NIS+, the fully qualified domain name
is case-insensitive and terminated by a dot character ('.').
For NIS, the fully qualified domain name is case-sensitive
and is not terminated by a dot character. For both NIS+ and
NIS, <server address> is optional. If it is not supplied, a
host name lookup will be performed to get the machine's
address.
For example, if the machine wiz-nisplus-server with address
133.33.33.33 serves the NIS+ domain wiz.com., the reference
would look like this:
wiz.com. wiz-nisplus-server 133.33.33.33
For NIS, the reference information is of the form:
<domainname> <server name>
For example, if the machine woz-nis-server serves the NIS
domain Woz.COM, the reference would look like this:
Woz.COM woz-nis-server
After obtaining this information, you then edit the DNS
table (see in.named(1M)) and add a TXT record with this
reference information. The TXT record must be associated
with a DNS domain that includes an NIS record. For example,
the reference information shown in the examples above would
be entered as follows.
For NIS+:
TXT "XFNNISPLUS wiz.com. wiz-nisplus-server
133.33.33.33"
For NIS:
TXT "XFNNIS woz.com woz-nis-server"
Note the mandatory double quotes ('"') delimiting the con-
tents of the TXT record. After making any changes to the
DNS table, you must notify the server by either restarting
it or sending it a signal to reread the table:
#kill -HUP `cat /etc/named.pid`
This update effectively adds the next naming system refer-
ence to DNS. You can look up this reference using
fnlookup(1) to see if the information has been added prop-
erly. For example, the following command looks up the next
naming system reference of the DNS domain Wiz.COM:
#fnlookup -v .../Wiz.COM/
Note the mandatory trailing slash ('/').
After this administrative step has been taken, clients out-
side of the NIS+ hierarchy or NIS domain can access and per-
form operations on the contexts in the NIS+ hierarchy or NIS
domain. Foreign NIS+ clients access the hierarchy as unau-
thenticated NIS+ clients. Continuing the example above, and
assuming that NIS+ is federated underneath the DNS domain
Wiz.COM, you can now list the root of the NIS+ enterprise
using the command:
#fnlist .../Wiz.COM/
SEE ALSO
fnlist(1), fnlookup(1), nis+(1), in.named(1M), ypserv(1M),
xfn(3XFN), fns(5), fns_nis(5), fns_nis+(5),
fns_references(5), fns_x500(5)
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