{"id":3933,"date":"2022-12-20T17:28:26","date_gmt":"2022-12-20T20:28:26","guid":{"rendered":"http:\/\/lode.uno\/linux-man\/index.php\/2022\/12\/20\/ddp-man7\/"},"modified":"2022-12-20T17:28:26","modified_gmt":"2022-12-20T20:28:26","slug":"ddp-man7","status":"publish","type":"post","link":"https:\/\/lode.uno\/linux-man\/2022\/12\/20\/ddp-man7\/","title":{"rendered":"DDP (man7)"},"content":{"rendered":"

DDP<\/h1>\n

NAME<\/a>
SYNOPSIS<\/a>
DESCRIPTION<\/a>
ERRORS<\/a>
VERSIONS<\/a>
NOTES<\/a>
BUGS<\/a>
SEE ALSO<\/a>
COLOPHON<\/a> <\/p>\n

\n

NAME <\/a> <\/h2>\n

ddp \u2212 Linux AppleTalk protocol implementation<\/p>\n

SYNOPSIS <\/a> <\/h2>\n

#include
#include <\/b><\/p>\n

ddp_socket<\/i> = socket(AF_APPLETALK, SOCK_DGRAM, 0);<\/b>
raw_socket<\/i> = socket(AF_APPLETALK, SOCK_RAW,<\/b> protocol<\/i>);<\/b><\/p>\n

DESCRIPTION <\/a> <\/h2>\n

Linux implements the AppleTalk protocols described in Inside AppleTalk<\/i>. Only the DDP layer and AARP are present in the kernel. They are designed to be used via the netatalk<\/b> protocol libraries. This page documents the interface for those who wish or need to use the DDP layer directly.<\/p>\n

The communication between AppleTalk and the user program works using a BSD-compatible socket interface. For more information on sockets, see socket<\/b>(7).<\/p>\n

An AppleTalk socket is created by calling the socket<\/b>(2) function with a AF_APPLETALK<\/b> socket family argument. Valid socket types are SOCK_DGRAM<\/b> to open a ddp<\/b> socket or SOCK_RAW<\/b> to open a raw<\/b> socket. protocol<\/i> is the AppleTalk protocol to be received or sent. For SOCK_RAW<\/b> you must specify ATPROTO_DDP<\/b>.<\/p>\n

Raw sockets may be opened only by a process with effective user ID 0 or when the process has the CAP_NET_RAW<\/b> capability.<\/p>\n

Address format<\/b>
An AppleTalk socket address is defined as a combination of a network number, a node number, and a port number.<\/p>\n

struct at_addr {
unsigned short s_net;
unsigned char s_node;
};<\/p>\n

struct sockaddr_atalk {
sa_family_t sat_family; \/bin \/boot \/dead.letter \/dev \/etc \/home \/initrd \/lib \/lib64 \/lost+found \/media \/mnt \/opt \/proc \/release-notes.html \/release-notes.txt \/root \/run \/sbin \/srv \/sys \/tmp \/usr \/var address family bodies\/ usr\/
unsigned char sat_port; \/bin \/boot \/dead.letter \/dev \/etc \/home \/initrd \/lib \/lib64 \/lost+found \/media \/mnt \/opt \/proc \/release-notes.html \/release-notes.txt \/root \/run \/sbin \/srv \/sys \/tmp \/usr \/var port bodies\/ usr\/
struct at_addr sat_addr; \/bin \/boot \/dead.letter \/dev \/etc \/home \/initrd \/lib \/lib64 \/lost+found \/media \/mnt \/opt \/proc \/release-notes.html \/release-notes.txt \/root \/run \/sbin \/srv \/sys \/tmp \/usr \/var net\/node bodies\/ usr\/
};<\/p>\n

sat_family<\/i> is always set to AF_APPLETALK<\/b>. sat_port<\/i> contains the port. The port numbers below 129 are known as reserved ports<\/i>. Only processes with the effective user ID 0 or the CAP_NET_BIND_SERVICE<\/b> capability may bind<\/b>(2) to these sockets. sat_addr<\/i> is the host address. The net<\/i> member of struct at_addr<\/i> contains the host network in network byte order. The value of AT_ANYNET<\/b> is a wildcard and also implies \u201cthis network.\u201d The node<\/i> member of struct at_addr<\/i> contains the host node number. The value of AT_ANYNODE<\/b> is a wildcard and also implies \u201cthis node.\u201d The value of ATADDR_BCAST<\/b> is a link local broadcast address.<\/p>\n

Socket options<\/b>
No protocol-specific socket options are supported.<\/p>\n

\/proc interfaces<\/b>
IP supports a set of \/proc<\/i> interfaces to configure some global AppleTalk parameters. The parameters can be accessed by reading or writing files in the directory \/proc\/sys\/net\/atalk\/<\/i>.
aarp-expiry-time<\/i><\/p>\n

The time interval (in seconds) before an AARP cache entry expires.<\/p>\n

aarp-resolve-time<\/i><\/p>\n

The time interval (in seconds) before an AARP cache entry is resolved.<\/p>\n

aarp-retransmit-limit<\/i><\/p>\n

The number of retransmissions of an AARP query before the node is declared dead.<\/p>\n

aarp-tick-time<\/i><\/p>\n

The timer rate (in seconds) for the timer driving AARP.<\/p>\n

The default values match the specification and should never need to be changed.<\/p>\n

Ioctls<\/b>
All ioctls described in socket<\/b>(7) apply to DDP.<\/p>\n

ERRORS <\/a> <\/h2>\n\n\n
<\/td>\n\n

EACCES<\/b><\/p>\n<\/td>\n

<\/td>\n\n

The user tried to execute an operation without the necessary permissions. These include sending to a broadcast address without having the broadcast flag set, and trying to bind to a reserved port without effective user ID 0 or CAP_NET_BIND_SERVICE<\/b>.<\/p>\n<\/td>\n<\/tr>\n<\/table>\n

EADDRINUSE<\/b><\/p>\n

Tried to bind to an address already in use.<\/p>\n

EADDRNOTAVAIL<\/b><\/p>\n

A nonexistent interface was requested or the requested source address was not local.<\/p>\n\n\n
<\/td>\n\n

EAGAIN<\/b><\/p>\n<\/td>\n

<\/td>\n\n

Operation on a nonblocking socket would block.<\/p>\n<\/td>\n

 <\/td>\n<\/tr>\n<\/table>\n

EALREADY<\/b><\/p>\n

A connection operation on a nonblocking socket is already in progress.<\/p>\n

ECONNABORTED<\/b><\/p>\n

A connection was closed during an accept<\/b>(2).<\/p>\n

EHOSTUNREACH<\/b><\/p>\n

No routing table entry matches the destination address.<\/p>\n\n\n
<\/td>\n\n

EINVAL<\/b><\/p>\n<\/td>\n

<\/td>\n\n

Invalid argument passed.<\/p>\n<\/td>\n

 <\/td>\n<\/tr>\n<\/table>\n

EISCONN<\/b><\/p>\n

connect<\/b>(2) was called on an already connected socket.<\/p>\n

EMSGSIZE<\/b><\/p>\n

Datagram is bigger than the DDP MTU.<\/p>\n\n\n\n
<\/td>\n\n

ENODEV<\/b><\/p>\n<\/td>\n

<\/td>\n\n

Network device not available or not capable of sending IP.<\/p>\n<\/td>\n<\/tr>\n

<\/td>\n\n

ENOENT<\/b><\/p>\n<\/td>\n

<\/td>\n\n

SIOCGSTAMP<\/b> was called on a socket where no packet arrived.<\/p>\n<\/td>\n<\/tr>\n<\/table>\n

ENOMEM<\/b> and ENOBUFS<\/b><\/p>\n

Not enough memory available.<\/p>\n\n\n
<\/td>\n\n

ENOPKG<\/b><\/p>\n<\/td>\n

<\/td>\n\n

A kernel subsystem was not configured.<\/p>\n<\/td>\n

 <\/td>\n<\/tr>\n<\/table>\n

ENOPROTOOPT<\/b> and EOPNOTSUPP<\/b><\/p>\n

Invalid socket option passed.<\/p>\n

ENOTCONN<\/b><\/p>\n

The operation is defined only on a connected socket, but the socket wasn\u2019t connected.<\/p>\n\n\n\n
<\/td>\n\n

EPERM<\/b><\/p>\n<\/td>\n

<\/td>\n\n

User doesn\u2019t have permission to set high priority, make a configuration change, or send signals to the requested process or group.<\/p>\n<\/td>\n<\/tr>\n

<\/td>\n\n

EPIPE<\/b><\/p>\n<\/td>\n

<\/td>\n\n

The connection was unexpectedly closed or shut down by the other end.<\/p>\n<\/td>\n<\/tr>\n<\/table>\n

ESOCKTNOSUPPORT<\/b><\/p>\n

The socket was unconfigured, or an unknown socket type was requested.<\/p>\n

VERSIONS <\/a> <\/h2>\n

AppleTalk is supported by Linux 2.0 or higher. The \/proc<\/i> interfaces exist since Linux 2.2.<\/p>\n

NOTES <\/a> <\/h2>\n

Be very careful with the SO_BROADCAST<\/b> option; it is not privileged in Linux. It is easy to overload the network with careless sending to broadcast addresses.<\/p>\n

Compatibility<\/b>
The basic AppleTalk socket interface is compatible with netatalk<\/b> on BSD-derived systems. Many BSD systems fail to check SO_BROADCAST<\/b> when sending broadcast frames; this can lead to compatibility problems.<\/p>\n

The raw socket mode is unique to Linux and exists to support the alternative CAP package and AppleTalk monitoring tools more easily.<\/p>\n

BUGS <\/a> <\/h2>\n

There are too many inconsistent error values.<\/p>\n

The ioctls used to configure routing tables, devices, AARP tables, and other devices are not yet described.<\/p>\n

SEE ALSO <\/a> <\/h2>\n

recvmsg<\/b>(2), sendmsg<\/b>(2), capabilities<\/b>(7), socket<\/b>(7)<\/p>\n

COLOPHON <\/a> <\/h2>\n

This page is part of release 5.10 of the Linux man-pages<\/i> project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https:\/\/www.kernel.org\/doc\/man\u2212pages\/.<\/p>\n

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