ifconfig is a utilty can used for getting information about network interfaces and stack, chagning them or adding virtual interfaces.

running `ifconfig` without any options will show usually something like this:

    lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 32768
            index 3 priority 0 llprio 3
            groups: lo
            inet6 ::1 prefixlen 128
            inet6 fe80::1%25lo0 prefixlen 64 scopeid 0x3
            inet 127.0.0.1 netmask 0xff000000
    em0: flags=8b43<UP,BROADCAST,RUNNING,PROMISC,ALLMULTI,SIMPLEX,MULTICAST> mtu 1500
            lladdr aa:bb:cc:dd:ee:ff
            index 1 priority 0 llprio 3
            groups: egress
            media: Ethernet autoselect
            status: active
            inet 12.34.56.78 netmask 0xffffff00 broadcast 12.34.56.78
            inet6 2002::ffff:ccff:fedd:ee06%25vio0 prefixlen 64 scopeid 0x1
            inet6 2002:ffff:2:1040:: prefixlen 48
    enc0: flags=0<>
            index 2 priority 0 llprio 3
            groups: enc
            status: active
    pflog0: flags=141<UP,RUNNING,PROMISC> mtu 33136
            index 4 priority 0 llprio 3
            groups: pflo


besides em0, all other interfaces mentioned (pflog0, enc0, lo0) are virtual and they will exist on all openbsd installations most of times.

    em0: flags=8b43<UP,BROADCAST,RUNNING,PROMISC,ALLMULTI,SIMPLEX,MULTICAST> mtu 1500


it shows em0's mtu (maximum size of a packet) and flags set on it. some can changed using software, some are hardware-dependent and can't without changing hardware.

    lladdr aa:bb:cc:dd:ee:ff


this refer about MAC adderss used by this interface, which is `aa:bb:cc:dd:ee:ff`

    inet 12.34.56.78 netmask 0xffffff00 broadcast 12.34.56.78


this is referring to ip address, netmask and broadcast address

ip address can be local, if you are using NAT

    inet6 2002:ffff:2:1040:: prefixlen 48


`inet6` is like `inet` but for ipv6.