Interface configurator - display your ip address, network interfaces, transferred and received data information, configure a network interface. On most modern distributions ifconfig has been depracated, use ip instead.
Syntax ifconfig [interface] ifconfig interface [aftype] options | address ... Options interface The name of the interface. Usually a driver name followed by a unit number, eth0 = 1st Ethernet interface. up This flag causes the interface to be activated. It is implicitly specified if an address is assigned to the interface. down This flag causes the driver for this interface to be shut down. [-]arp Enable or disable the use of the ARP protocol on this interface. [-]promisc Enable or disable the promiscuous mode of the interface. If selected, all packets on the network will be received by the interface. [-]allmulti Enable or disable all-multicast mode. If selected, all multicast packets on the network will be received by the interface. metric N Set the interface metric. mtu N Set the Maximum Transfer Unit (MTU) of an interface. To make this change permanent, edit: /etc/network/interfaces Debian / Ubuntu /etc/sysconfig/network-scripts/ifcfg-eth0 CentOS/RHEL/Fedora dstaddr addr Set the remote IP address for a point-to-point (PPP)link (obsolete; use pointopoint instead) netmask addr Set the IP network mask for this interface. This value defaults to the usual class A, B or C network mask (as derived from the interface IP address), but it can be set to any value. add addr/prefixlen Add an IPv6 address to an interface. del addr/prefixlen Remove an IPv6 address from an interface. tunnel aa.bb.cc.dd Create a new SIT (IPv6-in-IPv4) device, tunnelling to the given destination. irq addr Set the interrupt line used by this device. Not all devices can dynamically change their IRQ setting. io_addr addr Set the start address in I/O space for this device. mem_start addr Set the start address for shared memory used by this device. Only a few devices need this. media type Set the physical port or medium type to be used by the device. Not all devices can change this setting, and those that can vary in what values they support. Typical values for type are 10base2 (thin Ethernet), 10baseT (twisted-pair 10Mbps Ethernet), AUI (external transceiver) and so on. The special medium type of auto can be used to tell the driver to auto-sense the media. Again, not all drivers can do this. [-]broadcast [addr] If the address argument is given, set the protocol broadcast address for this interface. Otherwise, set (or clear) the IFF_BROADCAST flag for the interface. [-]pointopoint [addr] This keyword enables the point-to-point mode of an interface,meaning that it is a direct link between two machines with nobody else listening on it. If the address argument is also given, set the protocol address of the other side of the link, just like the obsolete dstaddr keyword does. Otherwise, set or clear the IFF_POINTOPOINT flag for the interface. hw class address Set the hardware address of this interface, if the device driver supports this operation. The keyword must be followed by the name of the hardware class and the printable ASCII equivalent of the hardware address. Hardware classes currently supported include ether (Ethernet), ax25 (AMPR AX.25), ARCnet and netrom (AMPR NET/ROM). multicast Set the multicast flag on the interface. Not normally be needed as the drivers set the flag correctly themselves. address The IP address to be assigned to this interface. txqueuelen length Set the length of the transmit queue of the device. It is useful to set this to small values for slower devices with a high latency (modem links, ISDN) to prevent fast bulk transfers from disturbing interactive traffic like telnet too much.
ifconfig is used at boot time to set up interfaces as necessary. After that, it is usually only needed when debugging or when system tuning is needed.
If no arguments are given, ifconfig displays the status of the currently active interfaces. If a single interface argument is given, it displays the status of the given interface only; if a single -a argument is given, it displays the status of all interfaces, even those that are down. Otherwise, it configures an interface.
If the first argument after the interface name is recognized as the name of a supported address family, that address family is used for decoding and displaying all protocol addresses. Currently supported address families include inet (TCP/IP, default), inet6 (IPv6), ax25 (AMPR Packet Radio), ddp (Appletalk Phase 2), ipx (Novell IPX) and netrom (AMPR Packet radio).
All numbers supplied as parts in IPv4 dotted decimal notation can be decimal, octal, or hexadecimal, as specified in the ISO C standard (that is, a leading 0x or 0X implies hexadecimal; otherwise, a leading '0' implies octal; otherwise, the number is interpreted as decimal). Use of hexamedial and octal numbers is not RFC-compliant and therefore its use is discouraged and might go away.
Change the state of the network interface device(s) to UP:
$ ifconfig eth0 up
Change the state of the network interface device(s) to DOWN: (see also ip link)
$ ifconfig eth0 dn
“A Connection Manager connection does not connect after being disconnected” ~ Title of Microsoft KnowledgeBase article
netstat(1) - Networking information
ip - Routing, devices and tunnels
Equivalent Windows command: NETSH - Configure Interfaces