172 lines
3.3 KiB
Text
172 lines
3.3 KiB
Text
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.TH BRIDGE 3
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.SH NAME
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bridge \- IPv4 Ethernet bridge
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.SH SYNOPSIS
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.nf
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.B bind -a #B\fIb\fP /net
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.B /net/bridge\fIb\fP/ctl
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.B /net/bridge\fIb\fP/cache
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.B /net/bridge\fIb\fP/log
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.B /net/bridge\fIb\fP/stats
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.BI /net/bridge\fIb\fP/ n
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.BI /net/bridge\fIb\fP/ n /ctl
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.BI /net/bridge\fIb\fP/ n /local
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.BI /net/bridge\fIb\fP/ n /status
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.fi
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.SH DESCRIPTION
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The
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.I bridge
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device bridges IPv4 packets amongst Ethernet interfaces.
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The number
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.I b
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in the bind is optional and selects a particular bridge
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(default 0).
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.PP
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The
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.B /net/bridge0
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directory contains
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.BR ctl ,
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.BR cache ,
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.BR log ,
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and
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.B stats
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files, and numbered subdirectories for each physical interface.
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.PP
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Opening the
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.B ctl
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file reserves an interface.
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The file descriptor returned from the
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.IR open (2)
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will point to the control file,
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.BR ctl ,
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of the newly allocated interface.
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Reading
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.B ctl
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returns a text string representing the number of the interface.
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Writing
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.B ctl
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alters aspects of the interface.
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The possible
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.I ctl
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messages are:
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.TF cacheflush
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.PD
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.TP
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.BI "bind ether " "name ownhash path"
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Treat the device mounted at
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.I path
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(e.g.,
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.LR /net/ether0 )
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as an Ethernet medium carrying IPv4 and ARP packets
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and associate it with this bridge (forward its packets to the
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other interfaces associated with this bridge).
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.I Ownhash
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is an `owner hash'.
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.TP
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.BI "bind tunnel " "name ownhash path path2
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Treat the device mounted at
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.I path
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as a network tunnel carrying IPv4 and ARP packets,
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the device mounted at
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.I path2
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as an Ethernet medium carrying IPv4 and ARP packets
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and associate them with this bridge
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(forward its packets to the
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other interfaces associated with this bridge).
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Read packets from the
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.I path
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interface and write them to the
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.I path2
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interface.
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Such tunnels have an MTU of 1400 bytes.
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.TP
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.BI "unbind " "type address [ownhash]"
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Disassociate the interface associated with
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.I address
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from this bridge.
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.I Type
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must be
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.L ether
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or
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.LR tunnel .
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.TP
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.B cacheflush
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Clear the cache of (destination MAC address, port) tuples.
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.TP
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.BI "delay " "delay0 delayn"
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Set the
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.I delay0
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and
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.I delayn
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parameters.
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.I delay0
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is the constant microsecond delay per packet
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and
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.I delayn
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is the microsecond delay per byte.
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.TP
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.BI "set " option
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Set bridge
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.IR option .
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The only known option is
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.LR tcpmss ,
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which limits the TCP Maximum Segment Size of
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TCPv4 packets passing through to 1300 bytes.
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.TP
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.BI "clear " option
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Clear bridge
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.IR option .
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.PP
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Reading
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.I stats
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returns statistics about the bridge.
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.PP
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Reading the
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.I log
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file returns data from the bridge's log
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and will block at end of file awaiting new data.
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.PP
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Reading the
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.B cache
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file prints the cache of (destination MAC address, port) tuples,
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one entry per line.
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The format is:
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the destination MAC (e.g., Ethernet) address in hex,
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port number,
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count of packets from this address,
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count of packets to this address,
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expiry time in seconds since the epoch,
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and
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.L e
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for expired entries or
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.L v
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for valid entries.
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.PP
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In a connection subdirectory,
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.B ctl
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and
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.B local
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don't do anything,
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but
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.B status
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returns a one-line status summary.
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.SH EXAMPLES
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Set up a network bridge between two Ethernets
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.RL ( #l0
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and
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.LR #l1 ).
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.IP
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.EX
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bind -a '#B' /net
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bind -a '#l1' /net
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echo 'bind ether outer 0 /net/ether0' >/net/bridge0/ctl
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echo 'bind ether inner 0 /net/ether1' >/net/bridge0/ctl
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.EE
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.SH "SEE ALSO"
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.IR ip (3)
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.SH SOURCE
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.B /sys/src/9/port/devbridge.c
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.SH BUGS
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Doesn't understand IPv6.
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