atalk.local(5) FILE FORMATS atalk.local(5)
NAME
atalk.local - configuration file for CAP.
DESCRIPTION
atalk.local contains the static configuration information
needed to run the CAP system with IPTalk (See CAP(8)). This
document defines the permissible contents of atalk.local for
this distribution.
The version of CAP that supports Ethertalk uses another file
called etalk.local. The contents of etalk.local are "free
format" with keyword identifiers for each piece of informa-
tion. The file is written by both UAB and the Native Ether-
talk AARP daemon aarpd after they have identified the net-
work, node and zone name. Refer to etalk.local(5) and UAB(8)
for more information. If atalk.local exists, it is used to
"seed" values that are not otherwise obtained from the net-
work.
Unlike LocalTalk and EtherTalk hosts, IPTalk based CAP hosts
do not dynamically establish their AppleTalk addresses,
zones, or the network's AppleTalk bridge. The primary func-
tion of atalk.local is to define these values.
The format of the file for IPTalk is quite simple. There
are two significant lines in the file, and two extra lines
which are optional (the third line is mandatory if the
fourth line is used). There may also be any number of com-
ment lines, which are identified by an initial pound sign
(#) character. The first significant line defines the
AppleTalk address of the host. The second line defines
which AppleTalk Bridge to use. This bridge must be running
software that supports the IPTalk (KIP) encapsulation. For
example:
# host's AppleTalk network, node, zone
55.1 6 "MY ZONE"
# bridge's AppleTalk network, node, and IP address
55.1 5 128.254.1.5
A network number can be specified as a single number or as
two bytes separated by a "." (as above).
IMPORTANTNOTE: An underscore in the zone name is no longer
treated as a space as in previous versions. If a space in a
zone name is desired, then use double or single forward ("
or ') quotes to surround the name, as in the example shown
above. This is the same convention used by later versions
of atalkad. To have a quote in the zone name, escape it with
a backslash (\).
OPTIONAL LINES
atalk.local may have up to two more (non comment) lines. The
third line describes the network and node number for the NIS
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atalk.local(5) FILE FORMATS atalk.local(5)
information server. That is, the network and node numbers
for the host that is running atis, see atis(8). If this line
is not present, the network and node numbers are taken from
the first (host) line.
The optional fourth line (meaning you MUST HAVE a NIS entry)
specifies the network and zone name for Asynchronous
AppleTalk running on this host. Async AppleTalk allows con-
nection to AppleTalk networks via serial lines connected to
UNIX hosts. The entry specifies a Network number and Zone
name that belong to this host only and must match the 'A'
entries in atalkatab (using atalkad 1.23 or later available
via FTP from munnari.OZ.AU). This service is currently only
available with a Webster MultiPort Gateway, Shiva FastPath
(early 1991) and when CAP is used with UAB.
A fully qualified atalk.local would therefore look like
this.
# host's AppleTalk network, node, zone
55.1 6 "MY ZONE"
# bridge's AppleTalk network, node, and IP address
55.1 5 128.254.1.5
# name information server network, node
55.1 6
# async appletalk network and zone
170.32 "Async Zone"
The contents of atalk.local for IPtalk follow rigidly from
what is defined in atalkad's atalkatab file. Remember that
atalkatab defines mappings for IP subnets to AppleTalk net-
works. The host's appletalk network number must set as one
of those mappings for the subnet that the host is on. In
addition, the zone name specified in atalk.local must be the
zone name of the appletalk network specified. The host's
node number must be the last byte of the host's ip network
number. For more information on why this is necessary, see
the section on IPTalk routing below.
The AppleTalk bridge information comes from the anete net-
work number in atalkatab. The anete network number is the
one specified in the bridge's configuration for the UDP
encapsulated "interface". When using the anete network
number for the bridge, its AppleTalk node number MUST EQUAL
the last byte of its IP address.
The overall combination of the Async AppleTalk UNIX code and
the specified bridge form the "pseudo" Async AppleTalk
bridge.
IPTalk ROUTING
Appletalk bridges that implement IPtalk route to UDP
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atalk.local(5) FILE FORMATS atalk.local(5)
encapsulated networks by using the AppleTalk to IP mappings
(N[0123] and "H" flagged lines) defined in atalkatab to go
from AppleTalk network numbers to IP network numbers and
vice versa. Of particular interest is that it assumes that
the IP address of a host can be found by replacing the last
byte of the IP address defined in the mapping with the DDP
node number. (Remember, KIP encapsulates DDP packets not
LAP packets). This has two major consequences. First, the
node numbers of KIP/CAP hosts must be the same as the last
byte of their IP network numbers.
Second, Appletalk to IP network mappings are expected to
cover subnets (8 bit subnets for Class B networks, 16 bit
for Class A networks). For the purposes of routing, it does
not matter how your IP networks are really subnetted (or not
subnetted). However, the mapping also defines a second
piece of information. It tells how to broadcast NBP lookup
requests to all hosts on a particular UDP capsulated
Appletalk network and the underlying IP network structure is
of importance here. Unfortunately, the details of this
issue are beyond the scope of this document.
FILES
atalk.local usually resides in /etc
BUGS
The node numbers should be automatically determined since
they are fixed. In addition, it would be nice if the zone
name were picked up automatically as well.
SEE ALSO
KIP documentation
CAP(3), CAP(8), atalkatab(5), atalkad(8), atis(8)
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