LINUX COMMANDS

ip [options] object command [arguments]
ip [object [command]] help

System administration command. Show and manipulate network devices and routing. This command is a part of the iproute2 utilities
for controlling TCP and UDP IP networking and traffic control. It’s meant to replace the ifconfig, route, and arp commands among
others. On some distributions these utilities may be deprecated in favor of ip.

ip’s subcommand syntax is very similar to the Cisco’s IOS syntax used on many Cisco routers and switches. The ip command can be
used to configure tunnels, load balancing and other traffic shaping. For brevity, we won’t cover all of its features here. For more indepth
coverage, we recommend iproute2’s Linux Foundation web pages at: http://www.linuxfoundation.org/en/Net:Iproute2.

Linux Commad Options:
-s, --stats, --statistics
Print statistics or time values. Use multiple times to increase the verbosity of output even more.
-f protocol_family, --family protocol_family
Specify the protocol_family to use for the commands given. This may be inet, inet6, or link. The protocol_family link may
be used to indicate no protocol is involved. The ip command also accepts shortcut options of -4, -6, and -0 for families inet, inet6, and link.
-o, --oneline
Format output as one line, replacing linefeeds with the ‘’ character. This is useful when piping output of ip to another command.
-r, --resolve
Resolve IP addresses to host names. The default is to use IP addresses.

Commands
We will only cover commands for address, link, neighbor and route objects, and the syntax of the help command. These are the
commands that replace ifconfig, arp, and route. (In IPv4 the neighbor table is known as the arp table.) Most objects and
commands have a long name (or two) as well as one or more abbreviations. For example, the object address can be given as address,
addr, or a. The commands show and list are interchangeable and can be abbreviated as sh, s, li, or l. Here we show the most
commonly used form in examples and documentation:

help
List command syntax, including applicable arguments. The syntax is given in a form similar to BNF grammar notation.
addr add address[/netmask] arguments
Add a new protocol address to a device. The format of the address depends on the protocol (inet or inet6). A netmask
may be given in CIDR notation. If no netmask is given, a mask of /32 is assumed.
addr del address[/netmask] [arguments]
Remove a protocol address.
addr show [arguments]
Print current addresses.
link set device_name [arguments]
Define or change settings on a network device.
link show [device_name]
Print current settings for network devices.
neigh add address [arguments]
Add a new entry to the neighbor table for the IPv4 or IPv6 address.

neigh chg address [arguments]
Change an existing entry in the neighbor table.
neigh del address [arguments]
Mark as invalid then remove an entry from the neighbor table when released from all clients.
neigh list [address] [arguments]
Add a new entry or change an existing one in the neighbor table.
neigh repl address [arguments]
Add a new entry or change an existing one in the neighbor table.
neigh flush arguments
Flush the specified entries from neighbors table. This command requires an argument, either an address, address prefix, dev,
nud, or unused argument.
route add address [arguments]
Add a new entry to the routing table.
route chg address [arguments]
Change an existing entry in the routing table.
route del address [arguments]
Remove an entry from the routing.
route list [arguments]
Show current routing table entries. Use arguments to limit the entries shown.
route repl address [arguments]
Add a new entry or change an existing one in the routing table.

Common arguments
The following are common arguments for the above commands:
address address[/netmask]
Set a link layer address (i.e., MAC address) for a network device.
arp on, arp off
Set the arp flag of a network device on or off.
brd address
Set the broadcast address. Addresses for address objects may also be given as the symbols + or – meaning to set all the host
bits of the broadcast address to 1 or 0. When used with a link object, this argument sets the link layer broadcast address
instead.
dev name
The name of the network device to which the command applies (e.g., lo or eth0.) For link object commands you can omit dev and just pass the name as the first argument.

down, up
Change the state of a network device, disabling or enabling it (or limit shown devices to those with the specified state).
dynamic on, dynamic off
Set the dynamic flag of a network device on or off.
label name
Assign a label string of name to an address.
local address
The IPv4 or IPv6 address to use with addr object commands. For these commands you can omit local and just pass the address as the first argument.
lladdr address
Set a link layer address for a neighbors table entry.
mtu n
Set the maximum transfer unit (MTU) for a network device to n. multicast on, multicast off
Set the multicast flag of a network device on or off.

nud state
Set the neighbor unreachability detection (nud) state of a neighbor entry. State values include:
noarp
Mark the entry as valid and not to be checked. It may be removed when it expires.
permanent
Like noarp, but a permanent entry can only be removed by an administrator.
reachable
Mark the entry as valid until its reachability timeout expires.
stale
Mark a new or changed entry as valid, but suspicious. The kernel will check stale entries at the first transmission.

promisc on, promisc off
Turn promiscuous mode on or off for a network device.
proto protocol
Set the routing protocol. The protocol identifies how a route was entered. If you are manually entering a route, the appropriate value for protocol should be static. If not specified the protocol defaults to boot.
scope value
Set the valid scope of an address or route entry. Valid values include global, site, link, and host. If used with the show
command, only addresses of the given scope will be shown.
src address
The preferred IPv4 or IPv6 source address for a routing table entry.

to address
The IPv4 or IPv6 address or address prefix for a neighbor table or routing table entry. For neigh and route object commands
you can omit the to and pass the address as the first argument. For route object commands you may also use the special
address default, which is equivalent to an address of 0/0 or /0.
tos key
An 8-bit hexadecimal number or the IPv4 or IPv6 address or address prefix for a neighbor table or routing table entry. For
neigh and route object commands you can omit the to and pass the address as the first argument.
txqlen n
Set the transmit queue length of a network device to n.
unused
When given with neigh show, show only unused entries.
via address
The address of the nexthop router (e.g., the Ipv4 or IPv6 address of the gateway). Used with route commands.

Examples: