Chapter 4. AppleTalk
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# Chapter 4. AppleTalk

## AppleTalk Transport Layer

AppleTalk is a network protocol family created by Apple which predates TCP/IP. It contains different protocols for different uses: address resolution, address/name mapping, service location, establishing connections, and the like.

Netatalk implements the AppleTalk protocols to serve files over AFP and provide other services to old Mac and Apple II clients.

A complete overview can be found inside the developer documentation.

### To use AppleTalk or not

You'll need the AppleTalk support built into Netatalk to provide file services to older AFP clients not capable of using AFP over TCP. It also enables printing services via PAP by papd(8), a timeserver timelord(8) for older Mac clients, and NetBoot server a2boot(8) for Apple II clients.

In addition, if you are serving Classic Mac OS clients, you might consider using AppleTalk for service propagation/location, having the ease of use for your network clients in mind. The Apple engineers implemented a way to easily locate an AFP server via AppleTalk but establishing the AFP connection itself via AFP over TCP (see the developer documentation for details on this cool feature, too).

To use the different base AppleTalk protocols with Netatalk, one has to use atalkd(8). It can also be used as an AppleTalk router to connect different independent network segments to each other.

To use AppleTalk/atalkd, your system has to have kernel support for AppleTalk. If missing, you will be restricted to AFP over TCP, and won't be able to use either of the AppleTalk services described in this chapter.

Example 4.1. Enable AppleTalk in afp.conf

    appletalk = yes

If Netatalk has been built with AppleTalk support (pass `-Dwith-appletalk=true` to the build system), this activates AFP over AppleTalk.

### No AppleTalk routing

This is the most simple form, you can use AppleTalk with netatalk. In case, you have only one network interface up and running, you haven't to deal with atalkd's config at all: atalkd will use AppleTalk's self-configuration features to get an AppleTalk address and to register itself in the network automagically.

In case, you have more than one active network interface, you have to make a decision:

#### Using only one interface

Just add the interface name (en1, le0, eth2, ... for example) to atalkd.conf on a single line. Do only list one interface here.

Example 4.2. atalkd.conf containing one entry

    eth0

AppleTalk networking should be enabled on eth0 interface. All the necessary configuration will be fetched from the network

At startup time, atalkd will add the real settings (address and network and eventually a zone) to atalkd.conf on its own

Example 4.3. atalkd.conf containing one entry after atalkd started

    eth0 -phase 2 -net 0-65534 -addr 65280.166

atalkd filled in the AppleTalk settings that apply to this network segment. A netrange of 0-65534 indicates that there is no AppleTalk router present, so atalkd will fetch an address that matches the following criteria: netrange from inside the so called "startup range" 65280-65533 and a node address between 142 and 255.

#### Using several interfaces

When using several interfaces you have to add them line by line following the -dontroute switch in atalkd.conf.

Example 4.4. atalkd.conf containing several entries with the -dontroute option

    eth0 -dontroute eth1 -dontroute eth2 -dontroute

AppleTalk networking should be enabled on all three interfaces, but no routing should be done between the different segments. Again, all the necessary configuration will be fetched from the connected networks.

Example 4.5. atalkd.conf containing several entries with the -dontroute option after atalkd started

    eth0 -dontroute -phase 2 -net 0-65534 -addr 65280.152
    eth1 -dontroute -phase 2 -net 0-65534 -addr 65280.208
    eth2 -dontroute -phase 2 -net 1-1000 -addr 10.142 -zone "Printers"

On eth0 and eth1, there are no other routers present, so atalkd chooses an address from within the startup range. But on eth2 there lives an already connected AppleTalk router, publishing one zone called "Printers" and forcing clients to assign themselves an address in a netrange between 1 and 1000.

In this case, atalkd will handle each interface as it would be the only active one. This can have some side effects when it comes to the point where AFP clients want to do the magic switch from AppleTalk to TCP, so use this with caution.

In case, you have more than one active network interface and do not take special precautions as outlined above, then autoconfiguration of the interfaces might fail in a situation where one of your network interfaces is connected to a network where no other active AppleTalk router is present and supplies appropriate routing settings.

For further information see atalkd.conf(5) and the developer documentation.

### atalkd acting as an AppleTalk router

Several types of AppleTalk routers exist: seed, non-seed and so called soft-seed routers.

- A seed router has its own configuration and publishes this into the network segments it is configured for.

- A non-seed router needs a seed router on the interface to which it is connected to learn the network configuration. So this type of AppleTalk router can work completely without manual configuration.

- A so called soft-seed router is exactly the same as a non-seed router except the fact, that it can also remember the configuration of a seed router and act as a replacement in case, the real seed router disappears from the net.

Netatalk's atalkd can act as both a seed and a soft-seed router, even in a mixed mode, where it acts on one interface in this way and on the other in another.

If you leave your atalkd.conf completely empty or simply add all active interfaces line by line without using seed settings (atalkd will act identically in both cases), then atalkd is forced to act as a soft-seed router on each interface, so it will fail on the first interface, where no seed router is accessible to fetch routing information from.

In this case, other services, that depend on atalkd, might also fail.

So you should have atalkd act as a seed router on one or all active interfaces. A seed router has to supply informations about:

- The specific netrange on this segment

- Its own AppleTalk address

- The zones (one to many) available in this segment

- The so called "default zone" for this segment

### Warning

Unless you are the network admin yourself, consider asking them before changing anything related to AppleTalk routing, as changing these settings might have side effects for all of your AppleTalk network clients!

In an AppleTalk network netranges have to be unique and must not overlap each other. Fortunately netatalk's atalkd is polite enough to check whether your settings are in conflict with already existing ones on the net. In such a case it simply discards your settings and tries to adapt the already established ones on the net (if in doubt, always check syslog for details).

Netranges, you can use, include pretty small ones, eg. 42-42, to very large ones, eg. 1-65279 - the latter one representing the maximum. In routed environments you can use any numbers in the range between 1 and 65279 unless they do not overlap with settings of other connected subnets.

The own AppleTalk address consists of a net part and a node part (the former 16 bit, the latter 8 bit, for example 12057.143). Apple recommends using node addresses of 128 or above for servers, letting client Macs assign themselves an address faster (as they will primarily search for a node address within 1-127 in the supplied netrange). As we don't want to get in conflict with Apple servers, we prefer using node addresses of 142 or above.

AppleTalk zones have nothing to do with physical networks. They're just a hint for your client's convenience, letting them locate network resources in a more comfortable/faster way. You can either use one zone name across multiple physical segments as well as more than one zone name on a single segment (and various combinations of this).

So all you have to do is to draw a network chart containing the physical segments, the netranges you want to assign to each one, the zone names you want to publish in which segments and the default zone per segment (this is always the first zone name, you supply with the -zone switch in atalkd.conf).

If you finished the steps outlined above, you might want to edit atalkd.conf to fit your needs.

You'll have to set the following options in atalkd.conf:

- -net (use reasonable values between 1-65279 for each interface)

  In case, this value is suppressed but -addr is present, the netrange from this specific address will be used

- -addr (the net part must match the -net settings if present, the node address should be between 142 and 255)

- -zone (can be used multiple times in one single line, the first entry is the default zone)

Note that you are able to set up "zone mapping", that means publishing exactly the same zone name on all AppleTalk segments, as well as providing more than one single zone name per interface. Dumb AppleTalk devices, like LaserWriters, will always register themselves in the default zone (the first zone entry you use in atalkd.conf per interface), more intelligent ones will have the ability to choose one specific zone via a user interface.

Example 4.6. atalkd.conf making netatalk a seed router on two interfaces

    eth0 -seed -phase 2 -net 1-1000 -addr 1000.142 -zone "Printers" -zone "Spoolers"
    eth1 -seed -phase 2 -net 1001-2000 -addr 2000.142 -zone "Macs" -zone "Servers"

The settings for eth0 force AppleTalk devices within the connected network to assign themselves an address in the netrange 1-1000. Two zone names are published into this segment, "Printers" being the so called "standard zone", forcing dumb AppleTalk devices like Laser printers to show up automatically into this zone. AppleTalk printer queues supplied by netatalk's papd can be registered into the zone "Spoolers" simply by adjusting the settings in papd.conf(5). On eth1 we use the different and non-overlapping netrange 1001-2000, set the default zone to "Macs" and publish a fourth zone name "Servers".

Example 4.7. atalkd.conf configured for "zone mapping"

    eth0 -seed -phase 2 -net 1-1000 -addr 1000.142 -zone "foo"
    lo0 -phase 1 -net 1 -addr 1.142 -zone "foo"

We use the same network settings as in the example above but let atalkd publish the same zone name on both segments. As the same zone name will be used on all segments of the AppleTalk network no zone names will show up at all... but AppleTalk routing will still be active. In this case, we connect a so called "non-extended" LocalTalk network (phase 1) to an EtherTalk "extended" network (phase 2) transparently.

Example 4.8. atalkd.conf for a soft-seed router configuration

    eth0 eth1 eth2

As we have more than one interface, atalkd will try to act as an AppleTalk router between both segments. As we don't supply any network configuration on our own we depend on the availability of seed routers in every connected segment. If only one segment is without such an available seed router the whole thing will fail.

Example 4.9. atalkd.conf for a soft-seed router configuration after atalkd started

    eth0 -phase 2 -net 10-10 -addr 10.166 -zone "Parking"
    eth1 -phase 2 -net 10000-11000 -addr 10324.151 -zone "No Parking" -zone "Parking"
    eth2 -phase 2 -net 65279-65279 -addr 65279.142 -zone "Parking" -zone "No Parking"

In this case, active seed routers are present in all three connected networks, so atalkd was able to fetch the network configuration from them and, since the settings do not conflict, act as a soft-seed router from now on between the segments. So even in case, all of the three seed routers would disappear from the net, atalkd would still supply the connected network with the network configuration once learned from them. Only in case, atalkd would be restarted afterwards, the routing information will be lost (as we're not acting as seed router).

Example 4.10. atalkd.conf ready for mixed seed/soft-seed mode

    eth0
    eth1 -seed -phase 2 -net 99-100 -addr 99.200 -zone "Testing"

In case in the network connected to eth0 lives no active seed router or one with a mismatching configuration (eg. an overlapping netrange of 1-200) atalkd will fail. Otherwise it will fetch the configuration from this machine and will route between eth0 and eth1, on the latter acting as a seed router itself.

By the way: It is perfectly legal to have more than one seed router connected to a network segment. But in this case, you should take care that the configuration of all connected routers is exactly the same regarding netranges, published zone names and also the "standard zone" per segment

## Printing

Netatalk can act both as a PAP client to access AppleTalk-capable printers, and as a PAP server. The former by using the pap(1) utility and the latter by starting the papd(8) service.

The "Printer Access Protocol" as part of the AppleTalk protocol suite is a fully 8 bit aware and bidirectional printing protocol, developed by Apple in 1985. 8 bit aware means that the whole set of bytes can be used for printing (binary encoding). This has been a great advantage compared with other protocols like Adobe's Standard Protocol to drive serial and parallel PostScript printers (compare with Adobe TechNote 5009) or LPR which made only use of the lower 128 bytes for printing because the 8th bit has been reserved for control codes.

Bidirectional means that printing source (usually a Macintosh computer) and destination (a printer or spooler implementation) communicate about both destination's capabilities via feature queries (compare with Adobe TechNote 5133) and device status. This allows the LaserWriter driver on the Macintosh to generate appropriate device specific PostScript code (color or b/w, only embedding needed fonts, and so on) on the one hand and notifications about the printing process or problems (paper jam for example) on the other.

### Setting up the PAP print server

Netatalk's papd is able to provide AppleTalk printing services for Macintoshes or, to be more precise, PAP clients in general. Netatalk does not contain a full-blown spooler implementation itself, papd only handles the bidirectional communication and submittance of printjobs from PAP clients. So normally one needs to integrate papd with a Unix printing system like eg. classic SysV lpd, BSD lpr, LPRng, CUPS or the like.

Since it is so important to answer the client's feature queries correctly, how does papd achieve this? By parsing the relevant keywords of the assigned PPD file. When using CUPS, papd will attempt to generate a PPD file on the fly by querying the printer via IPP. With other spoolers, choosing the correct PPD is important to be able to print.

Netatalk formerly had built-in support for System V lpd printing in a way that papd saved the printed job directly into the spooldir and calls lpd afterwards, to pick up the file and do the rest. Due to incompatibilities with many lpd implementations the normal behaviour was to print directly into a pipe instead of specifying a printer by name and using lpd interaction. As of Netatalk 2.0, another alternative has been implemented: direct interaction with CUPS (Note: when CUPS support is compiled in, then the SysV lpd support doesn't work at all). Detailed examples can be found in the papd.conf(5) manual page.

#### Integrating papd with SysV lpd

Unless CUPS support has been compiled in (which is default from Netatalk 2.0 on) one simply defines the lpd queue in question by setting the `pr` parameter to the queue name. If no `pr` parameter is set, the default printer will be used.

#### Using pipes with papd

An alternative to the technique outlined above is to direct papd's output via a pipe into another program. Using this mechanism almost all printing systems can be driven.

#### Using direct CUPS support

Starting with Netatalk 2.0, direct CUPS integration is available. In this case, defining only a queue name as `pr` parameter won't invoke the SysV lpd daemon but uses CUPS instead. Unless a specific PPD has been assigned using the `pd` switch, the PPD configured in CUPS will be used by papd, too.

There exists one special share named cupsautoadd. If this is present in papd.conf, then all available CUPS queues will be served automagically using the parameters assigned to this global share. But subsequent printer definitions can be used to override these global settings for individual spoolers.

Example 4.11. Example syntax, assigning root as operator:

    cupsautoadd:op=root:

### Using AppleTalk printers

Netatalk's papstatus(8) can be used to query AppleTalk printers, pap(1) to print to them.

pap can be used stand-alone or as part of an output filter or a CUPS backend (which is the preferred method since one does not have to deal with all the options).

Example 4.12. pap printing to a PostScript LaserWriter

    pap -p"ColorLaserWriter 16/600@*" /usr/share/doc/gs/examples/tiger.ps

The file `/usr/share/doc/gs/examples/tiger.ps` is sent to a printer called "ColorLaserWriter 16/600" in the standard zone "*". The device type is "LaserWriter" (can be suppressed since it is the default).

Example 4.13. pap printing to a non-PostScript printer

    gs -q -dNOPAUSE -sDEVICE=cdjcolor -sOutputFile=test.ps | pap -E

GhostScript is used to convert a PostScript job to PCL3 output suitable for a Color DeskWriter. Since no file has been supplied on the command line, pap reads the data from stdin. The printer's address will be read from the `.paprc` file in the same directory, pap will be called (in our example simply containing "Color DeskWriter:DeskWriter@Printers"). The `-E` switch forces pap to not wait for an EOF from the printer.

## Time Services

### Timelord

timelord, an AppleTalk based time server, is useful for automatically synchronizing the system time on older Macintosh or Apple II clients that do not support NTP.

Netatalk's timelord is compatible with the tardis client for Macintosh developed at the University of Melbourne.

For further information please have a look at the timelord(8) manual page.

## NetBoot Services

### Apple 2 NetBooting

a2boot is a service that allows you to boot an Apple //e or Apple IIGS into ProDOS or GS/OS through an AFP volume served by Netatalk.

You need to supply the appropriate boot blocks and system files provided by Apple yourself.

For further information please have a look at the a2boot(8) manual page.

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