Difference between revisions of "Network interface"
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| − | A network interface is the interface to a network node or a certain Network Interface Card (NIC) perhaps an | + | A network interface is the interface to a network node or a certain Network Interface Card (NIC) perhaps an [[ethernet]] card. An interface can be virtual or physical. To see all network interfaces on a system use the [[ifconfig]] command. |
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$ ifconfig -a | $ ifconfig -a | ||
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inet6 fe80::260:8ff:fe5a:8682%xl0 prefixlen 64 scopeid 0x2 | inet6 fe80::260:8ff:fe5a:8682%xl0 prefixlen 64 scopeid 0x2 | ||
| − | When a computer has multiple network interfaces and passes [[IP]] traffic from one interface to another interface it is called a [[router]]. Similarely if a computer passes [[ | + | |
| + | |||
| + | When a computer has multiple network interfaces and passes [[IP]] traffic from one interface to another interface it is called a [[router]]. Similarely if a computer passes [[ethernet]] frames from one NIC to another it is called a [[bridge]]. | ||
If you want to be sure that traffic is being routed or bridged you can attach a [[bpf]] program like tcpdump to a network interface and watch a packet entering interface a and exiting on interface b. | If you want to be sure that traffic is being routed or bridged you can attach a [[bpf]] program like tcpdump to a network interface and watch a packet entering interface a and exiting on interface b. | ||
Revision as of 05:35, 13 October 2005
A network interface is the interface to a network node or a certain Network Interface Card (NIC) perhaps an ethernet card. An interface can be virtual or physical. To see all network interfaces on a system use the ifconfig command.
$ ifconfig -a
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 33192
groups: lo
inet 127.0.0.1 netmask 0xff000000
inet6 ::1 prefixlen 128
inet6 fe80::1%lo0 prefixlen 64 scopeid 0x9
wi0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
lladdr 00:02:2d:09:4b:44
media: IEEE802.11 autoselect (DS2)
status: active
ieee80211: nwid ATLAS -12dBm (auto)
inet 10.0.0.2 netmask 0xff000000 broadcast 10.255.255.255
inet6 fe80::202:2dff:fe09:4b44%wi0 prefixlen 64 scopeid 0x1
xl0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
lladdr 00:60:08:5a:86:82
media: Ethernet 100baseTX full-duplex
status: no carrier
inet 172.16.2.2 netmask 0xfffffe00 broadcast 172.16.3.255
inet6 fe80::260:8ff:fe5a:8682%xl0 prefixlen 64 scopeid 0x2
When a computer has multiple network interfaces and passes IP traffic from one interface to another interface it is called a router. Similarely if a computer passes ethernet frames from one NIC to another it is called a bridge.
If you want to be sure that traffic is being routed or bridged you can attach a bpf program like tcpdump to a network interface and watch a packet entering interface a and exiting on interface b.
