diff --git a/en_US.ISO8859-1/books/handbook/advanced-networking/chapter.xml b/en_US.ISO8859-1/books/handbook/advanced-networking/chapter.xml index fcbaacdb26..4fa6806c74 100644 --- a/en_US.ISO8859-1/books/handbook/advanced-networking/chapter.xml +++ b/en_US.ISO8859-1/books/handbook/advanced-networking/chapter.xml @@ -2848,104 +2848,106 @@ rfcomm_sppd[94692]: Starting on /dev/ttyp6... bridge - It is sometimes useful to divide a network, - such as an Ethernet segment, into network - segments without having to create IP - subnets and use a router to connect the segments together. - A device that connects two networks together in this fashion - is called a bridge. + It is sometimes useful to divide a network, such as an + Ethernet segment, into network segments without having to + create IP subnets and use a router to connect + the segments together. A device that connects two networks + together in this fashion is called a + bridge. - A bridge works by learning the MAC - addresses of the devices on each of its - network interfaces. It forwards traffic between networks - only when the source and destination MAC addresses are on different - networks. In many respects, a bridge is like an Ethernet switch with - very few ports. A &os; system with multiple - network interfaces can be configured to act as a bridge. + A bridge works by learning the MAC + addresses of the devices on each of its network interfaces. It + forwards traffic between networks only when the source and + destination MAC addresses are on different + networks. In many respects, a bridge is like an Ethernet switch + with very few ports. A &os; system with multiple network + interfaces can be configured to act as a bridge. - Bridging can be useful in the following situations: + Bridging can be useful in the following situations: - - + + Connecting Networks - The basic operation of a bridge is to join two or more - network segments. There are many reasons to use a - host-based bridge instead of networking equipment, such as - cabling constraints or firewalling. A bridge can - also connect a wireless interface running in hostap mode to - a wired network and act as an access point. - - + The basic operation of a bridge is to join two or more + network segments. There are many reasons to use a + host-based bridge instead of networking equipment, such as + cabling constraints or firewalling. A bridge can also + connect a wireless interface running in hostap mode to a + wired network and act as an access point. + + - + Filtering/Traffic Shaping Firewall - A bridge can be used when firewall functionality is - needed without routing or Network Address Translation - (NAT). + A bridge can be used when firewall functionality is + needed without routing or Network Address Translation + (NAT). - An example is a small company that is connected via - DSL - or ISDN to an ISP. - There are thirteen public IP - addresses from the ISP and ten computers - on the network. In this situation, using a router-based - firewall is difficult because of subnetting issues. A bridge-based firewall can be configured without any - IP addressing issues. - - + An example is a small company that is connected via + DSL or ISDN to an + ISP. There are thirteen public + IP addresses from the + ISP and ten computers on the network. + In this situation, using a router-based firewall is + difficult because of subnetting issues. A bridge-based + firewall can be configured without any + IP addressing issues. + + Network Tap - A bridge can join two network segments in order to - inspect all Ethernet frames that pass between them using - &man.bpf.4; and &man.tcpdump.1; on the bridge interface or - by sending a copy of all frames out an additional interface - known as a span port. - - + A bridge can join two network segments in order to + inspect all Ethernet frames that pass between them using + &man.bpf.4; and &man.tcpdump.1; on the bridge interface or + by sending a copy of all frames out an additional + interface known as a span port. + + Layer 2 VPN - Two Ethernet networks can be joined across an - IP link by bridging the networks to an - EtherIP tunnel or a &man.tap.4; based solution such as - OpenVPN. - - + Two Ethernet networks can be joined across an + IP link by bridging the networks to an + EtherIP tunnel or a &man.tap.4; based solution such as + OpenVPN. + + Layer 2 Redundancy - A network can be connected together with multiple links - and use the Spanning Tree Protocol (STP) - to block redundant paths. - - - + A network can be connected together with multiple + links and use the Spanning Tree Protocol + (STP) to block redundant paths. + + + - This section describes how to configure a &os; system as a - bridge using &man.if.bridge.4;. - A netgraph bridging driver is also available, and is described - in &man.ng.bridge.4;. + This section describes how to configure a &os; system as a + bridge using &man.if.bridge.4;. A netgraph bridging driver is + also available, and is described in &man.ng.bridge.4;. - + Packet filtering can be used with any firewall package - that hooks into the &man.pfil.9; framework. The bridge can be used as a traffic shaper with - &man.altq.4; or &man.dummynet.4;. - + that hooks into the &man.pfil.9; framework. The bridge can be + used as a traffic shaper with &man.altq.4; or + &man.dummynet.4;. + Enabling the Bridge In &os;, &man.if.bridge.4; is a kernel module which is automatically loaded by &man.ifconfig.8; when creating a - bridge interface. It is also possible to compile bridge support - into a custom kernel by adding device if_bridge - to the custom kernel configuration file. + bridge interface. It is also possible to compile bridge + support into a custom kernel by adding + device if_bridge to the custom kernel + configuration file. The bridge is created using interface cloning. To create the bridge interface: @@ -2968,19 +2970,18 @@ bridge0: flags=8802<BROADCAST,SIMPLEX,MULTICAST> metric 0 mtu 1500 The other parameters control how STP operates. - Next, specify which network interfaces to add as members of the bridge. - For the bridge to forward packets, all member interfaces and - the bridge need to be up: + Next, specify which network interfaces to add as members + of the bridge. For the bridge to forward packets, all member + interfaces and the bridge need to be up: &prompt.root; ifconfig bridge0 addm fxp0 addm fxp1 up &prompt.root; ifconfig fxp0 up &prompt.root; ifconfig fxp1 up The bridge can now forward Ethernet frames between - fxp0 and - fxp1. Add the following lines to - /etc/rc.conf so the bridge is created - at startup: + fxp0 and fxp1. Add + the following lines to /etc/rc.conf so + the bridge is created at startup: cloned_interfaces="bridge0" ifconfig_bridge0="addm fxp0 addm fxp1 up" @@ -2988,9 +2989,8 @@ ifconfig_fxp0="up" ifconfig_fxp1="up" If the bridge host needs an IP - address, set it on the bridge - interface, not on the member interfaces. - The address can be set statically or via + address, set it on the bridge interface, not on the member + interfaces. The address can be set statically or via DHCP. This example sets a static IP address: @@ -3002,48 +3002,44 @@ ifconfig_fxp1="up" /etc/rc.conf. - When packet filtering is enabled, bridged packets will - pass through the filter inbound on the originating interface - on the bridge interface, and outbound on the appropriate - interfaces. Either stage can be disabled. When direction of - the packet flow is important, it is best to firewall on the - member interfaces rather than the bridge itself. + When packet filtering is enabled, bridged packets will + pass through the filter inbound on the originating interface + on the bridge interface, and outbound on the appropriate + interfaces. Either stage can be disabled. When direction + of the packet flow is important, it is best to firewall on + the member interfaces rather than the bridge itself. - The bridge has several configurable settings for passing - non-IP and IP packets, - and layer2 firewalling with &man.ipfw.8;. See - &man.if.bridge.4; for more information. + The bridge has several configurable settings for passing + non-IP and IP packets, + and layer2 firewalling with &man.ipfw.8;. See + &man.if.bridge.4; for more information. Enabling Spanning Tree - For an Ethernet network to - function properly, only one active path can exist between - two devices. The STP protocol detects loops and - puts redundant links into a blocked state. Should one - of the active links fail, STP - calculates a different tree and enables one of the blocked - paths to restore connectivity to all points in the - network. + For an Ethernet network to function properly, only one + active path can exist between two devices. The + STP protocol detects loops and puts + redundant links into a blocked state. Should one of the + active links fail, STP calculates a + different tree and enables one of the blocked paths to restore + connectivity to all points in the network. - The Rapid Spanning Tree - Protocol (RSTP or 802.1w) provides backwards - compatibility with legacy STP. - RSTP provides - faster convergence and - exchanges information with neighboring switches - to quickly transition to forwarding mode without creating loops. - &os; supports RSTP and + The Rapid Spanning Tree Protocol (RSTP + or 802.1w) provides backwards compatibility with legacy + STP. RSTP provides + faster convergence and exchanges information with neighboring + switches to quickly transition to forwarding mode without + creating loops. &os; supports RSTP and STP as operating modes, with RSTP being the default mode. STP can be enabled on member interfaces using &man.ifconfig.8;. For a bridge with - fxp0 and - fxp1 as the current interfaces, - enable STP with: + fxp0 and fxp1 as the + current interfaces, enable STP with: &prompt.root; ifconfig bridge0 stp fxp0 stp fxp1 bridge0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500 @@ -3088,163 +3084,163 @@ bridge0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1 - Bridge Interface Parameters + Bridge Interface Parameters - Several ifconfig parameters are unique - to bridge interfaces. This section summarizes some common - uses for these parameters. The complete list of available parameters is - described in &man.ifconfig.8;. + Several ifconfig parameters are unique + to bridge interfaces. This section summarizes some common + uses for these parameters. The complete list of available + parameters is described in &man.ifconfig.8;. - - - private - - A private interface does not forward any traffic to any - other port that is also designated as a private interface. The traffic is - blocked unconditionally so no Ethernet frames will be - forwarded, including ARP packets. If traffic - needs to be selectively blocked, a firewall should be used - instead. - - + + + private + + A private interface does not forward any traffic to + any other port that is also designated as a private + interface. The traffic is blocked unconditionally so no + Ethernet frames will be forwarded, including + ARP packets. If traffic needs to be + selectively blocked, a firewall should be used + instead. + + - - span - - A span port transmits a copy of every Ethernet frame received by the bridge. - The number - of span ports configured on a bridge is unlimited, but if an - interface is designated as a span port, it cannot also be - used as a regular bridge port. This is most useful for - snooping a bridged network passively on another host - connected to one of the span ports of the bridge. For - example, to send a copy of all frames out the interface named - fxp4: + + span + + A span port transmits a copy of every Ethernet frame + received by the bridge. The number of span ports + configured on a bridge is unlimited, but if an + interface is designated as a span port, it cannot also + be used as a regular bridge port. This is most useful + for snooping a bridged network passively on another host + connected to one of the span ports of the bridge. For + example, to send a copy of all frames out the interface + named fxp4: - &prompt.root; ifconfig bridge0 span fxp4 - - + &prompt.root; ifconfig bridge0 span fxp4 + + - - sticky - - If a bridge member interface is marked as sticky, - dynamically learned address entries are treated at static - entries in the forwarding cache. Sticky entries are - never aged out of the cache or replaced, even if the address - is seen on a different interface. This gives the benefit of - static address entries without the need to pre-populate the - forwarding table. Clients learned on a particular segment - of the bridge can not roam to another segment. + + sticky + + If a bridge member interface is marked as sticky, + dynamically learned address entries are treated at + static entries in the forwarding cache. Sticky entries + are never aged out of the cache or replaced, even if the + address is seen on a different interface. This gives + the benefit of static address entries without the need + to pre-populate the forwarding table. Clients learned + on a particular segment of the bridge can not roam to + another segment. - An example of using sticky addresses is to combine - the bridge with VLANs in order to isolate - customer networks without wasting - IP address space. Consider that - CustomerA is - on vlan100, CustomerB is on - vlan101, and the bridge has the address - 192.168.0.1: + An example of using sticky addresses is to combine + the bridge with VLANs in order to + isolate customer networks without wasting + IP address space. Consider that + CustomerA + is on vlan100, CustomerB is on + vlan101, and the bridge has the + address 192.168.0.1: - &prompt.root; ifconfig bridge0 addm vlan100 sticky vlan100 addm vlan101 sticky vlan101 + &prompt.root; ifconfig bridge0 addm vlan100 sticky vlan100 addm vlan101 sticky vlan101 &prompt.root; ifconfig bridge0 inet 192.168.0.1/24 - In this example, both clients see 192.168.0.1 as their - default gateway. Since the bridge cache is sticky, one host - can not spoof the MAC address of the - other customer in order to intercept their traffic. + In this example, both clients see 192.168.0.1 as their + default gateway. Since the bridge cache is sticky, one + host can not spoof the MAC address of + the other customer in order to intercept their + traffic. - Any communication between the VLANs - can be blocked using a firewall or, as seen in this example, - private interfaces: + Any communication between the + VLANs can be blocked using a firewall + or, as seen in this example, private interfaces: - &prompt.root; ifconfig bridge0 private vlan100 private vlan101 + &prompt.root; ifconfig bridge0 private vlan100 private vlan101 - The customers are completely isolated from each other - and the full /24 - address range can be allocated without subnetting. + The customers are completely isolated from each + other and the full /24 address range can be + allocated without subnetting. - The number of unique source MAC - addresses behind an interface can be limited. Once the - limit is reached, packets with unknown source addresses - are dropped until an existing host cache entry expires or - is removed. + The number of unique source MAC + addresses behind an interface can be limited. Once the + limit is reached, packets with unknown source addresses + are dropped until an existing host cache entry expires + or is removed. - The following example sets the maximum number of - Ethernet devices for CustomerA on - vlan100 to 10: + The following example sets the maximum number of + Ethernet devices for CustomerA on + vlan100 to 10: - &prompt.root; ifconfig bridge0 ifmaxaddr vlan100 10 - - - - - Bridge interfaces also support monitor mode, where the packets are - discarded after &man.bpf.4; processing and are not - processed or forwarded further. This can be used to - multiplex the input of two or more interfaces into a single - &man.bpf.4; stream. This is useful for reconstructing the - traffic for network taps that transmit the RX/TX signals out - through two separate interfaces. For example, - to read the input from four network interfaces as one - stream: + &prompt.root; ifconfig bridge0 ifmaxaddr vlan100 10 + + + - &prompt.root; ifconfig bridge0 addm fxp0 addm fxp1 addm fxp2 addm fxp3 monitor up -&prompt.root; tcpdump -i bridge0 - + Bridge interfaces also support monitor mode, where the + packets are discarded after &man.bpf.4; processing and are not + processed or forwarded further. This can be used to + multiplex the input of two or more interfaces into a single + &man.bpf.4; stream. This is useful for reconstructing the + traffic for network taps that transmit the RX/TX signals out + through two separate interfaces. For example, to read the + input from four network interfaces as one stream: - - <acronym>SNMP</acronym> Monitoring + &prompt.root; ifconfig bridge0 addm fxp0 addm fxp1 addm fxp2 addm fxp3 monitor up +&prompt.root; tcpdump -i bridge0 + - The bridge interface and STP - parameters can be monitored via &man.bsnmpd.1; which is - included in the &os; base system. The exported bridge - MIBs conform to - IETF standards so any - SNMP client or monitoring package can be - used to retrieve the data. + + <acronym>SNMP</acronym> Monitoring - To enable monitoring on the bridge, uncomment this - line in - /etc/snmp.config by removing the - beginning # symbol: + The bridge interface and STP + parameters can be monitored via &man.bsnmpd.1; which is + included in the &os; base system. The exported bridge + MIBs conform to IETF + standards so any SNMP client or monitoring + package can be used to retrieve the data. + + To enable monitoring on the bridge, uncomment this line in + /etc/snmp.config by removing the + beginning # symbol: + + begemotSnmpdModulePath."bridge" = "/usr/lib/snmp_bridge.so" - begemotSnmpdModulePath."bridge" = "/usr/lib/snmp_bridge.so" - - Other configuration settings, such as community - names and access lists, may need to be modified in this file. See - &man.bsnmpd.1; and &man.snmp.bridge.3; for more - information. Once these edits are saved, add this line to - /etc/rc.conf: - - bsnmpd_enable="YES" - - Then, start - &man.bsnmpd.1;: - - &prompt.root; service bsnmpd start + Other configuration settings, such as community names and + access lists, may need to be modified in this file. See + &man.bsnmpd.1; and &man.snmp.bridge.3; for more information. + Once these edits are saved, add this line to + /etc/rc.conf: - The following examples use the - Net-SNMP software - (net-mgmt/net-snmp) to query a bridge - from a client system. The - net-mgmt/bsnmptools port can also be - used. From the SNMP client which is - running Net-SNMP, add the - following lines to - $HOME/.snmp/snmp.conf in order to - import the bridge MIB definitions: + bsnmpd_enable="YES" - mibdirs +/usr/share/snmp/mibs + Then, start &man.bsnmpd.1;: + + &prompt.root; service bsnmpd start + + The following examples use the + Net-SNMP software + (net-mgmt/net-snmp) to query a bridge + from a client system. The + net-mgmt/bsnmptools port can also be used. + From the SNMP client which is running + Net-SNMP, add the following lines + to $HOME/.snmp/snmp.conf in order to + import the bridge MIB definitions: + + mibdirs +/usr/share/snmp/mibs mibs +BRIDGE-MIB:RSTP-MIB:BEGEMOT-MIB:BEGEMOT-BRIDGE-MIB - To monitor a single bridge using the IETF BRIDGE-MIB - (RFC4188): + To monitor a single bridge using the IETF BRIDGE-MIB + (RFC4188): - &prompt.user; snmpwalk -v 2c -c public bridge1.example.com mib-2.dot1dBridge + &prompt.user; snmpwalk -v 2c -c public bridge1.example.com mib-2.dot1dBridge BRIDGE-MIB::dot1dBaseBridgeAddress.0 = STRING: 66:fb:9b:6e:5c:44 BRIDGE-MIB::dot1dBaseNumPorts.0 = INTEGER: 1 ports BRIDGE-MIB::dot1dStpTimeSinceTopologyChange.0 = Timeticks: (189959) 0:31:39.59 centi-seconds @@ -3261,18 +3257,18 @@ BRIDGE-MIB::dot1dStpPortDesignatedPort.3 = Hex-STRING: 03 80 BRIDGE-MIB::dot1dStpPortForwardTransitions.3 = Counter32: 1 RSTP-MIB::dot1dStpVersion.0 = INTEGER: rstp(2) - The dot1dStpTopChanges.0 value is - two, indicating that the STP bridge - topology has changed twice. A topology change means that - one or more links in the network have changed or failed - and a new tree has been calculated. The - dot1dStpTimeSinceTopologyChange.0 value - will show when this happened. + The dot1dStpTopChanges.0 value is two, + indicating that the STP bridge topology has + changed twice. A topology change means that one or more links + in the network have changed or failed and a new tree has been + calculated. The + dot1dStpTimeSinceTopologyChange.0 value + will show when this happened. - To monitor multiple bridge interfaces, the private - BEGEMOT-BRIDGE-MIB can be used: + To monitor multiple bridge interfaces, the private + BEGEMOT-BRIDGE-MIB can be used: - &prompt.user; snmpwalk -v 2c -c public bridge1.example.com + &prompt.user; snmpwalk -v 2c -c public bridge1.example.com enterprises.fokus.begemot.begemotBridge BEGEMOT-BRIDGE-MIB::begemotBridgeBaseName."bridge0" = STRING: bridge0 BEGEMOT-BRIDGE-MIB::begemotBridgeBaseName."bridge2" = STRING: bridge2 @@ -3288,10 +3284,10 @@ BEGEMOT-BRIDGE-MIB::begemotBridgeStpTopChanges."bridge2" = Counter32: 1 BEGEMOT-BRIDGE-MIB::begemotBridgeStpDesignatedRoot."bridge0" = Hex-STRING: 80 00 00 40 95 30 5E 31 BEGEMOT-BRIDGE-MIB::begemotBridgeStpDesignatedRoot."bridge2" = Hex-STRING: 80 00 00 50 8B B8 C6 A9 - To change the bridge interface being monitored via the - mib-2.dot1dBridge subtree: + To change the bridge interface being monitored via the + mib-2.dot1dBridge subtree: - &prompt.user; snmpset -v 2c -c private bridge1.example.com + &prompt.user; snmpset -v 2c -c private bridge1.example.com BEGEMOT-BRIDGE-MIB::begemotBridgeDefaultBridgeIf.0 s bridge2