ETHER(3) ETHER(3)
NAME
ether - Ethernet device
SYNOPSIS
bind -a #ln /net
/net/ethern/clone
/net/ethern/addr
/net/ethern/ifstats
/net/ethern/stats
/net/ethern/[0-7]
/net/ethern/[0-7]/data
/net/ethern/[0-7]/ctl
/net/ethern/[0-7]/ifstats
/net/ethern/[0-7]/stats
/net/ethern/[0-7]/type
DESCRIPTION
The Ethernet interface, /net/ethern, is a directory contain-
ing subdirectories, one for each distinct Ethernet packet
type, and clone, addr, ifstats, and stats files. stats and
ifstats are the same as in the subdirectories (see below).
Reading addr returns the MAC address of this interface in
hex with no punctuation and no trailing newline. The number
n (optional in the bind) is the device number of the card,
permitting multiple cards to be used on a single machine.
Each directory contains files to control the associated con-
nection, receive and send data, and supply statistics.
Incoming Ethernet packets are demultiplexed by packet type
and passed up the corresponding open connection. Reading
from the data file reads packets of that type arriving from
the network. A read will terminate at packet boundaries.
Each write to the data file causes a packet to be sent. The
Ethernet address of the interface is inserted into the
packet header as the source address.
A connection is assigned to a packet type by opening its ctl
file and writing connect n where n is a decimal integer con-
stant identifying the Ethernet packet type. A type of -1
enables the connection to receive copies of packets of all
types. A type of -2 enables the connection to receive
copies of the first 64 bytes of packets of all types. If
multiple connections are assigned to a given packet type a
copy of each packet is passed up each connection.
Some interfaces also accept unique options when written to
the ctl (or clone) file; see the description of wavelan in
plan9.ini(8). The control messages described in ip(3) under
Configuring interfaces from `bridge' to `headersonly' are
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ETHER(3) ETHER(3)
understood. The additional control message `nonblocking'
makes write systems calls to this interface non-blocking iff
followed by nothing or a non-zero integer; a following `0'
makes writes block on a full output queue.
Reading the ctl file returns the decimal index of the asso-
ciated connection, 0 through 7. Reading the type file
returns the decimal value of the assigned Ethernet packet
type. Reading the stats file returns status information
such as the Ethernet address of the card and general statis-
tics, independent of the interface; ifstats contains
device-specific data and statistics about the card.
An interface normally receives only those packets whose des-
tination address is that of the interface or is the broad-
cast address, ff:ff:ff:ff:ff:ff. The interface can be made
to receive all packets on the network by writing the string
promiscuous to the ctl file. The interface remains promiscu-
ous until the control file is closed. The extra packets are
passed up connections only of types -1 and -2.
SOURCE
/sys/src/9/*/devether.c
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