How do I display a list of bridges under Linux? How do I show info about the Ethernet bridge configuration in the Linux kernel?
Bridging used in packet-switched networks and only used in local area networks. It connects multiple network segments at the Layer 2 so that these ethernets will appear as one ethernet to the participants.Each of the ethernets being connected corresponds to one physical interface in the bridge. These individual ethernets are bundled into one biggerethernet, this bigger ethernet corresponds to the bridge network interface.
brctl command
You need to use the brctl command, which is used to set up, maintain, and display the Ethernet bridge configuration in the Linux systems. Open a command-line terminal (select Applications > Accessories > Terminal), or login to remote system using the ssh client, and then type the following commands.
Linux Show All Instances of The Ethernet Bridge
Type the following command as the root user, enter:
# brctl show
Sample outputs:
bridge name bridge id STP enabled interfaces br0 8000.0030488e31ac no eth0 br1 8000.0030488e31ad no eth1
Display Mac Address
To display a list of learned MAC addresses for br0 bridge, enter:
# brctl showmacs br0
Sample outputs:
port no mac addr is local? ageing timer 1 00:1a:30:38:a8:00 no 0.00 1 00:1b:53:bb:a7:a1 no 5.06 1 00:30:48:32:d7:aa no 0.27 1 00:30:48:33:bc:32 no 0.03 1 00:30:48:8c:57:d2 no 0.65 1 00:30:48:8e:31:ac yes 0.00 1 02:30:48:8e:31:ac no 12.86
Show br0 IP Address Information
To see ip address assinged to br0, enter:
# ifconfig br0
OR
# ip addr show br0
Sample outputs:
br0 Link encap:Ethernet HWaddr 00:30:48:8E:31:AC inet addr:10.10.29.74 Bcast:10.10.29.127 Mask:255.255.255.192 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:382175211 errors:0 dropped:0 overruns:0 frame:0 TX packets:290454591 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:275381068495 (256.4 GiB) TX bytes:224019772370 (208.6 GiB)
How Do I See and Change Ethernet Bridge Network Configuration File?
Under RHEL / Fedora / CentOS / Redhat Linux Ethernet bridge network configuration for br0 stored as follows:
- /etc/sysconfig/network-scripts/ifcfg-eth0 – Specify bridge name
- /etc/sysconfig/network-scripts/ifcfg-br0 – br0 config file.
- /etc/sysconfig/network-scripts/route-br0 – Static routing (optional).
Debian or Ubuntu Linux user should use /etc/network/interfaces configuration file. A typical example is as follows:
# cat /etc/network/interfaces
Sample outputs:
# The loopback network interface auto lo br0 iface lo inet loopback # Set up interfaces manually iface eth0 inet manual iface eth1 inet manual # Bridge setup iface br0 inet static bridge_ports eth0 eth1 address 192.168.1.100 broadcast 192.168.1.255 netmask 255.255.255.0 gateway 192.168.1.254
See how to configure and use bridges under Linux here.
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