What are en0, en1, p2p, and so on, that are displayed after executing ifconfig?
The -v
flag provides a type info on some interfaces, for example IP over Thunderbolt
for en2
:
ifconfig -v en2
en2: flags=8963<UP,BROADCAST,SMART,RUNNING,PROMISC,SIMPLEX,MULTICAST> mtu 1500 index 6
eflags=41000080<TXSTART,ECN_ENABLE,FASTLN_ON>
options=460<TSO4,TSO6,CHANNEL_IO>
ether 82:02:9f:a3:0c:00
netif: EF77BC13-3B69-466C-8BA2-591CCA2D6C44
flowswitch: C155EE61-3E2C-465E-9AFB-17C36ECD8F8C
media: autoselect <full-duplex>
status: inactive
type: IP over Thunderbolt
agent domain:Skywalk type:NetIf flags:0xa443 desc:"Userspace Networking"
agent domain:Skywalk type:FlowSwitch flags:0x4403 desc:"Userspace Networking"
state availability: 0 (true)
scheduler: FQ_CODEL
qosmarking enabled: yes mode: none
low power mode: disabled
multi layer packet logging (mpklog): disabled
routermode4: disabled
routermode6: disabled
These are your network interfaces. Some are physical interfaces, and others are logical (virtual) interfaces.
en0
..X refer to your physical network interfaces. Most new Mac devices will just have en0
- your WiFi. en0
is the first device to start, en1
the second, etc.
lo0
is the 'loopback' interface. Otherwise known as localhost, or 127.0.0.1. The others are virtual interfaces.
In arbitrary order of my familarity / widespread relevance:
lo0
is loopback.
en0
at one point "ethernet", now is WiFi (and I have no idea what extra en1
or en2
are used for).
fw0
is the FireWire network interface.
stf0
is an IPv6 to IPv4 tunnel interface to support the transition from IPv4 to the IPv6 standard.
gif0
is a more generic tunneling interface [46]-to-[46].
awdl0
is Apple Wireless Direct Link
p2p0
is related to AWDL features. Either as an old version, or virtual interface with different semantics than awdl
.
Note also,
- the "Network" panel in System Preferences to see what network devices "exist" or "can exist" with current configuration.
- many VPNs will add additional devices, often "utun#" or "utap#" following TUN/TAP (L3/L2) virtual networking devices.
- use
netstat -nr
to see how traffic is currently routed via network devices according to destination. - interface naming conventions started in BSD were retained in OS X / macOS, and now there also additions.
Also answered in part on Apple SE here and there.