ref: a8d00e5d56b261376410c3c87c46327362763bd8
dir: /sys/man/3/bridge/
.TH BRIDGE 3 .SH NAME bridge \- IPv4 Ethernet bridge .SH SYNOPSIS .nf .B bind -a #B\fIb\fP /net .B /net/bridge\fIb\fP/ctl .B /net/bridge\fIb\fP/cache .B /net/bridge\fIb\fP/log .B /net/bridge\fIb\fP/stats .BI /net/bridge\fIb\fP/ n .BI /net/bridge\fIb\fP/ n /ctl .BI /net/bridge\fIb\fP/ n /local .BI /net/bridge\fIb\fP/ n /status .fi .SH DESCRIPTION The .I bridge device bridges IPv4 packets amongst Ethernet interfaces. The number .I b in the bind is optional and selects a particular bridge (default 0). .PP The .B /net/bridge0 directory contains .BR ctl , .BR cache , .BR log , and .B stats files, and numbered subdirectories for each physical interface. .PP Opening the .B ctl file reserves an interface. The file descriptor returned from the .IR open (2) will point to the control file, .BR ctl , of the newly allocated interface. Reading .B ctl returns a text string representing the number of the interface. Writing .B ctl alters aspects of the interface. The possible .I ctl messages are: .TF cacheflush .PD .TP .BI "bind ether " "name ownhash path" Treat the device mounted at .I path (e.g., .LR /net/ether0 ) as an Ethernet medium carrying IPv4 and ARP packets and associate it with this bridge (forward its packets to the other interfaces associated with this bridge). .I Ownhash is an `owner hash'. .TP .BI "bind tunnel " "name ownhash path path2 Treat the device mounted at .I path as a network tunnel carrying IPv4 and ARP packets, the device mounted at .I path2 as an Ethernet medium carrying IPv4 and ARP packets and associate them with this bridge (forward its packets to the other interfaces associated with this bridge). Read packets from the .I path interface and write them to the .I path2 interface. Such tunnels have an MTU of 1400 bytes. .TP .BI "unbind " "type address [ownhash]" Disassociate the interface associated with .I address from this bridge. .I Type must be .L ether or .LR tunnel . .TP .B cacheflush Clear the cache of (destination MAC address, port) tuples. .TP .BI "delay " "delay0 delayn" Set the .I delay0 and .I delayn parameters. .I delay0 is the constant microsecond delay per packet and .I delayn is the microsecond delay per byte. .TP .BI "set " option Set bridge .IR option . The only known option is .LR tcpmss , which limits the TCP Maximum Segment Size of TCPv4 packets passing through to 1300 bytes. .TP .BI "clear " option Clear bridge .IR option . .PP Reading .I stats returns statistics about the bridge. .PP Reading the .I log file returns data from the bridge's log and will block at end of file awaiting new data. .PP Reading the .B cache file prints the cache of (destination MAC address, port) tuples, one entry per line. The format is: the destination MAC (e.g., Ethernet) address in hex, port number, count of packets from this address, count of packets to this address, expiry time in seconds since the epoch, and .L e for expired entries or .L v for valid entries. .PP In a connection subdirectory, .B ctl and .B local don't do anything, but .B status returns a one-line status summary. .SH EXAMPLES Set up a network bridge between two Ethernets .RL ( #l0 and .LR #l1 ). .IP .EX bind -a '#B' /net bind -a '#l1' /net echo 'bind ether outer 0 /net/ether0' >/net/bridge0/ctl echo 'bind ether inner 0 /net/ether1' >/net/bridge0/ctl .EE .SH "SEE ALSO" .IR ip (3) .SH SOURCE .B /sys/src/9/port/devbridge.c .SH BUGS Doesn't understand IPv6.