ip link set DEVICE
{ up | down | arp { on | off } |
promisc { on | off } |
allmulti { on | off } |
dynamic { on | off } |
multicast { on | off } |
txqueuelenPACKETS |
nameNEWNAME |
addressLLADDR |
broadcast LLADDR |
mtuMTU }
ip link show
[ DEVICE ]
ip addr { add | del }
IFADDR dev STRING
ip addr { show | flush } [ devSTRING ] [
scopeSCOPE-ID ] [
to PREFIX ] [ FLAG-LIST ] [
labelPATTERN ]
ip neigh { show | flush } [ toPREFIX ] [
devDEV ] [
nudSTATE ]
ip tunnel { add | change | del | show }
[ NAME ]
[ mode { ipip | gre | sit } ]
[ remoteADDR ] [
localADDR ]
[ [i|o]seq ] [ [i|o]keyKEY ] [
[i|o]csum ] ]
[ ttlTTL ] [
tosTOS ] [
[no]pmtudisc ]
[ devPHYS_DEV ]
ADDR := { IP_ADDRESS |
any }
TOS := { NUMBER |
inherit }
TTL := { 1..255 |
inherit }
KEY := { DOTTED_QUAD | NUMBER }
ip maddr [ add | del ]
MULTIADDR dev STRING
ip maddr show [ devSTRING ]
ip mroute show [
PREFIX ] [
fromPREFIX ] [
iifDEVICE ]
ip monitor [ all |
LISTofOBJECTS ]
OPTIONS
-V, -Version
print the version of the
ip
utility and exit.
-s, -stats, -statistics
output more information. If the option
appears twice or more, the amount of information increases.
As a rule, the information is statistics or some time values.
-f, -family
followed by protocol family identifier:
inet, inet6
or
link
,enforce the protocol family to use. If the option is not present,
the protocol family is guessed from other arguments. If the rest
of the command line does not give enough information to guess the
family,
ip
falls back to the default one, usually
inet
or
any.
link
is a special family identifier meaning that no networking protocol
is involved.
-4
shortcut for
-family inet.
-6
shortcut for
-family inet6.
-0
shortcut for
-family link.
-o, -oneline
output each record on a single line, replacing line feeds
with the
''
character. This is convenient when you want to count records
with
wc(1)
or to
grep(1)
the output.
-r, -resolve
use the system's name resolver to print DNS names instead of
host addresses.
IP - COMMAND SYNTAX
OBJECT
link
- network device.
address
- protocol (IP or IPv6) address on a device.
neighbour
- ARP or NDISC cache entry.
route
- routing table entry.
rule
- rule in routing policy database.
maddress
- multicast address.
mroute
- multicast routing cache entry.
tunnel
- tunnel over IP.
The names of all objects may be written in full or
abbreviated form, f.e.
address
is abbreviated as
addr
or just
a.
COMMAND
Specifies the action to perform on the object.
The set of possible actions depends on the object type.
As a rule, it is possible to
add, delete
and
show
(or
list
) objects, but some objects do not allow all of these operations
or have some additional commands. The
help
command is available for all objects. It prints
out a list of available commands and argument syntax conventions.
If no command is given, some default command is assumed.
Usually it is
list
or, if the objects of this class cannot be listed,
help.
ip link - network device configuration
link
is a network device and the corresponding commands
display and change the state of devices.
ip link set - change device attributes
dev NAME (default)
NAME
specifies network device to operate on.
up and down
change the state of the device to
UP
or
DOWN.
arp on or arp off
change the
NOARP
flag on the device.
multicast on or multicast off
change the
MULTICAST
flag on the device.
dynamic on or dynamic off
change the
DYNAMIC
flag on the device.
name NAME
change the name of the device. This operation is not
recommended if the device is running or has some addresses
already configured.
txqueuelen NUMBER
txqlen NUMBER
change the transmit queue length of the device.
mtu NUMBER
change the
MTU
of the device.
address LLADDRESS
change the station address of the interface.
broadcast LLADDRESS
brd LLADDRESS
peer LLADDRESS
change the link layer broadcast address or the peer address when
the interface is
POINTOPOINT.
Warning:
If multiple parameter changes are requested,
ip
aborts immediately after any of the changes have failed.
This is the only case when
ip
can move the system to an unpredictable state. The solution
is to avoid changing several parameters with one
ip link set
call.
ip link show - display device attributes
dev NAME (default)
NAME
specifies the network device to show.
If this argument is omitted all devices are listed.
up
only display running interfaces.
ip address - protocol address management.
The
address
is a protocol (IP or IPv6) address attached
to a network device. Each device must have at least one address
to use the corresponding protocol. It is possible to have several
different addresses attached to one device. These addresses are not
discriminated, so that the term
alias
is not quite appropriate for them and we do not use it in this document.
The
ip addr
command displays addresses and their properties, adds new addresses
and deletes old ones.
ip address add - add new protocol address.
dev NAME
the name of the device to add the address to.
local ADDRESS (default)
the address of the interface. The format of the address depends
on the protocol. It is a dotted quad for IP and a sequence of
hexadecimal halfwords separated by colons for IPv6. The
ADDRESS
may be followed by a slash and a decimal number which encodes
the network prefix length.
peer ADDRESS
the address of the remote endpoint for pointopoint interfaces.
Again, the
ADDRESS
may be followed by a slash and a decimal number, encoding the network
prefix length. If a peer address is specified, the local address
cannot have a prefix length. The network prefix is associated
with the peer rather than with the local address.
broadcast ADDRESS
the broadcast address on the interface.
It is possible to use the special symbols
'+'
and
'-'
instead of the broadcast address. In this case, the broadcast address
is derived by setting/resetting the host bits of the interface prefix.
label NAME
Each address may be tagged with a label string.
In order to preserve compatibility with Linux-2.0 net aliases,
this string must coincide with the name of the device or must be prefixed
with the device name followed by colon.
scope SCOPE_VALUE
the scope of the area where this address is valid.
The available scopes are listed in file
/etc/iproute2/rt_scopes.
Predefined scope values are:
global
- the address is globally valid.
site
- (IPv6 only) the address is site local, i.e. it is
valid inside this site.
link
- the address is link local, i.e. it is valid only on this device.
host
- the address is valid only inside this host.
ip address delete - delete protocol address
Arguments:
coincide with the arguments of
ip addr add.
The device name is a required argument. The rest are optional.
If no arguments are given, the first address is deleted.
ip address show - look at protocol addresses
dev NAME (default)
name of device.
scope SCOPE_VAL
only list addresses with this scope.
to PREFIX
only list addresses matching this prefix.
label PATTERN
only list addresses with labels matching the
PATTERN.
PATTERN
is a usual shell style pattern.
dynamic and permanent
(IPv6 only) only list addresses installed due to stateless
address configuration or only list permanent (not dynamic)
addresses.
tentative
(IPv6 only) only list addresses which did not pass duplicate
address detection.
deprecated
(IPv6 only) only list deprecated addresses.
primary and secondary
only list primary (or secondary) addresses.
ip address flush - flush protocol addresses
This command flushes the protocol addresses selected by some criteria.
This command has the same arguments as
show.
The difference is that it does not run when no arguments are given.
Warning:
This command (and other
flush
commands described below) is pretty dangerous. If you make a mistake,
it will not forgive it, but will cruelly purge all the addresses.
With the
-statistics
option, the command becomes verbose. It prints out the number of deleted
addresses and the number of rounds made to flush the address list. If
this option is given twice,
ip addr flush
also dumps all the deleted addresses in the format described in the
previous subsection.
ip neighbour - neighbour/arp tables management.
neighbour
objects establish bindings between protocol addresses and
link layer addresses for hosts sharing the same link.
Neighbour entries are organized into tables. The IPv4 neighbour table
is known by another name - the ARP table.
The corresponding commands display neighbour bindings
and their properties, add new neighbour entries and delete old ones.
ip neighbour add - add a new neighbour entry
ip neighbour change - change an existing entry
ip neighbour replace - add a new entry or change an existing one
These commands create new neighbour records or update existing ones.
to ADDRESS (default)
the protocol address of the neighbour. It is either an IPv4 or IPv6 address.
dev NAME
the interface to which this neighbour is attached.
lladdr LLADDRESS
the link layer address of the neighbour.
LLADDRESS
can also be
null.
nud NUD_STATE
the state of the neighbour entry.
nud
is an abbreviation for 'Neigh bour Unreachability Detection'.
The state can take one of the following values:
permanent
- the neighbour entry is valid forever and can be only
be removed administratively.
noarp
- the neighbour entry is valid. No attempts to validate
this entry will be made but it can be removed when its lifetime expires.
reachable
- the neighbour entry is valid until the reachability
timeout expires.
stale
- the neighbour entry is valid but suspicious.
This option to
ip neigh
does not change the neighbour state if it was valid and the address
is not changed by this command.
ip neighbour delete - delete a neighbour entry
This command invalidates a neighbour entry.
The arguments are the same as with
ip neigh add,
except that
lladdr
and
nud
are ignored.
Warning:
Attempts to delete or manually change a
noarp
entry created by the kernel may result in unpredictable behaviour.
Particularly, the kernel may try to resolve this address even
on a
NOARP
interface or if the address is multicast or broadcast.
ip neighbour show - list neighbour entries
This commands displays neighbour tables.
to ADDRESS (default)
the prefix selecting the neighbours to list.
dev NAME
only list the neighbours attached to this device.
unused
only list neighbours which are not currently in use.
nud NUD_STATE
only list neighbour entries in this state.
NUD_STATE
takes values listed below or the special value
all
which means all states. This option may occur more than once.
If this option is absent,
ip
lists all entries except for
none
and
noarp.
ip neighbour flush - flush neighbour entries
This command flushes neighbour tables, selecting
entries to flush by some criteria.
This command has the same arguments as
show.
The differences are that it does not run when no arguments are given,
and that the default neighbour states to be flushed do not include
permanent
and
noarp.
With the
-statistics
option, the command becomes verbose. It prints out the number of
deleted neighbours and the number of rounds made to flush the
neighbour table. If the option is given
twice,
ip neigh flush
also dumps all the deleted neighbours.
ip route - routing table management
Manipulate route entries in the kernel routing tables keep
information about paths to other networked nodes.
Route types:
unicast
- the route entry describes real paths to the destinations covered
by the route prefix.
unreachable
- these destinations are unreachable. Packets are discarded and the
ICMP message
host unreachable
is generated.
The local senders get an
EHOSTUNREACH
error.
blackhole
- these destinations are unreachable. Packets are discarded silently.
The local senders get an
EINVAL
error.
prohibit
- these destinations are unreachable. Packets are discarded and the
ICMP message
communication administratively prohibited
is generated. The local senders get an
EACCES
error.
local
- the destinations are assigned to this host. The packets are looped
back and delivered locally.
broadcast
- the destinations are broadcast addresses. The packets are sent as
link broadcasts.
throw
- a special control route used together with policy rules. If such a
route is selected, lookup in this table is terminated pretending that
no route was found. Without policy routing it is equivalent to the
absence of the route in the routing table. The packets are dropped
and the ICMP message
net unreachable
is generated. The local senders get an
ENETUNREACH
error.
nat
- a special NAT route. Destinations covered by the prefix
are considered to be dummy (or external) addresses which require translation
to real (or internal) ones before forwarding. The addresses to translate to
are selected with the attribute
Warning:
Route NAT is no longer supported in Linux 2.6.
via.
anycast
- not implemented
the destinations are
anycast
addresses assigned to this host. They are mainly equivalent
to
local
with one difference: such addresses are invalid when used
as the source address of any packet.
multicast
- a special type used for multicast routing. It is not present in
normal routing tables.
Route tables:
Linux-2.x can pack routes into several routing
tables identified by a number in the range from 1 to 255 or by
name from the file
/etc/iproute2/rt_tablesmain
table (ID 254) and the kernel only uses this table when calculating routes.
Actually, one other table always exists, which is invisible but
even more important. It is the
local
table (ID 255). This table
consists of routes for local and broadcast addresses. The kernel maintains
this table automatically and the administrator usually need not modify it
or even look at it.
The multiple routing tables enter the game when
policy routing
is used.
ip route add - add new route
ip route change - change route
ip route replace - change or add new one
to TYPE PREFIX (default)
the destination prefix of the route. If
TYPE
is omitted,
ip
assumes type
unicast.
Other values of
TYPE
are listed above.
PREFIX
is an IP or IPv6 address optionally followed by a slash and the
prefix length. If the length of the prefix is missing,
ip
assumes a full-length host route. There is also a special
PREFIXdefault
- which is equivalent to IP
0/0
or to IPv6
::/0.
tos TOS
dsfield TOS
the Type Of Service (TOS) key. This key has no associated mask and
the longest match is understood as: First, compare the TOS
of the route and of the packet. If they are not equal, then the packet
may still match a route with a zero TOS.
TOS
is either an 8 bit hexadecimal number or an identifier
from
/etc/iproute2/rt_dsfield.
metric NUMBER
preference NUMBER
the preference value of the route.
NUMBER
is an arbitrary 32bit number.
table TABLEID
the table to add this route to.
TABLEID
may be a number or a string from the file
/etc/iproute2/rt_tables.
If this parameter is omitted,
ip
assumes the
main
table, with the exception of
local , broadcast and nat
routes, which are put into the
local
table by default.
dev NAME
the output device name.
via ADDRESS
the address of the nexthop router. Actually, the sense of this field
depends on the route type. For normal
unicast
routes it is either the true next hop router or, if it is a direct
route installed in BSD compatibility mode, it can be a local address
of the interface. For NAT routes it is the first address of the block
of translated IP destinations.
src ADDRESS
the source address to prefer when sending to the destinations
covered by the route prefix.
realm REALMID
the realm to which this route is assigned.
REALMID
may be a number or a string from the file
/etc/iproute2/rt_realms.
mtu MTU
mtu lock MTU
the MTU along the path to the destination. If the modifier
lock
is not used, the MTU may be updated by the kernel due to
Path MTU Discovery. If the modifier
lock
is used, no path MTU discovery will be tried, all packets
will be sent without the DF bit in IPv4 case or fragmented
to MTU for IPv6.
window NUMBER
the maximal window for TCP to advertise to these destinations,
measured in bytes. It limits maximal data bursts that our TCP
peers are allowed to send to us.
rtt NUMBER
the initial RTT ('Round Trip Time') estimate.
rttvar NUMBER (2.3.15+ only)
the initial RTT variance estimate.
ssthresh NUMBER (2.3.15+ only)
an estimate for the initial slow start threshold.
cwnd NUMBER (2.3.15+ only)
the clamp for congestion window. It is ignored if the
lock
flag is not used.
initcwnd NUMBER
The maximum initial congestion window (cwnd) size in MSS of a
TCP connection.
advmss NUMBER (2.3.15+ only)
the MSS ('Maximal Segment Size') to advertise to these
destinations when establishing TCP connections. If it is not given,
Linux uses a default value calculated from the first hop device MTU.
(If the path to these destination is asymmetric, this guess may be wrong.)
reordering NUMBER (2.3.15+ only)
Maximal reordering on the path to this destination.
If it is not given, Linux uses the value selected with
sysctl
variable
net/ipv4/tcp_reordering.
nexthop NEXTHOP
the nexthop of a multipath route.
NEXTHOP
is a complex value with its own syntax similar to the top level
argument lists:
via ADDRESS
- is the nexthop router.
dev NAME
- is the output device.
weight NUMBER
- is a weight for this element of a multipath
route reflecting its relative bandwidth or quality.
scope SCOPE_VAL
the scope of the destinations covered by the route prefix.
SCOPE_VAL
may be a number or a string from the file
/etc/iproute2/rt_scopes.
If this parameter is omitted,
ip
assumes scope
global
for all gatewayed
unicast
routes, scope
link
for direct
unicast and broadcast
routes and scope
host for local
routes.
protocol RTPROTO
the routing protocol identifier of this route.
RTPROTO
may be a number or a string from the file
/etc/iproute2/rt_protos.
If the routing protocol ID is not given,
ip assumes protocolboot
(i.e. it assumes the route was added by someone who doesn't
understand what they are doing). Several protocol values have
a fixed interpretation.
Namely:
redirect
- the route was installed due to an ICMP redirect.
kernel
- the route was installed by the kernel during autoconfiguration.
boot
- the route was installed during the bootup sequence.
If a routing daemon starts, it will purge all of them.
static
- the route was installed by the administrator
to override dynamic routing. Routing daemon will respect them
and, probably, even advertise them to its peers.
ra
- the route was installed by Router Discovery protocol.
The rest of the values are not reserved and the administrator is free
to assign (or not to assign) protocol tags.
onlink
pretend that the nexthop is directly attached to this link,
even if it does not match any interface prefix.
equalize
allow packet by packet randomization on multipath routes.
Without this modifier, the route will be frozen to one selected
nexthop, so that load splitting will only occur on per-flow base.
equalize
only works if the kernel is patched.
ip route delete - delete route
ip route del
has the same arguments as
ip route add,
but their semantics are a bit different.
Key values
(to, tos, preference and table)
select the route to delete. If optional attributes are present,
ip
verifies that they coincide with the attributes of the route to delete.
If no route with the given key and attributes was found,
ip route del
fails.
ip route show - list routes
the command displays the contents of the routing tables or the route(s)
selected by some criteria.
to SELECTOR (default)
only select routes from the given range of destinations.
SELECTOR
consists of an optional modifier
(root, match or exact)
and a prefix.
root PREFIX
selects routes with prefixes not shorter than
PREFIX.
F.e.
root 0/0
selects the entire routing table.
match PREFIX
selects routes with prefixes not longer than
PREFIX.
F.e.
match 10.0/16
selects
10.0/16,
10/8 and 0/0,
but it does not select
10.1/16 and 10.0.0/24.
And
exact PREFIX
(or just
PREFIX)
selects routes with this exact prefix. If neither of these options
are present,
ip
assumes
root 0/0
i.e. it lists the entire table.
tos TOS
dsfield TOS
only select routes with the given TOS.
table TABLEID
show the routes from this table(s). The default setting is to show
tablemain.TABLEID
may either be the ID of a real table or one of the special values:
all
- list all of the tables.
cache
- dump the routing cache.
cloned
cached
list cloned routes i.e. routes which were dynamically forked from
other routes because some route attribute (f.e. MTU) was updated.
Actually, it is equivalent to
table cache.
from SELECTOR
the same syntax as for
to,
but it binds the source address range rather than destinations.
Note that the
from
option only works with cloned routes.
protocol RTPROTO
only list routes of this protocol.
scope SCOPE_VAL
only list routes with this scope.
type TYPE
only list routes of this type.
dev NAME
only list routes going via this device.
via PREFIX
only list routes going via the nexthop routers selected by
PREFIX.
src PREFIX
only list routes with preferred source addresses selected
by
PREFIX.
realm REALMID
realms FROMREALM/TOREALM
only list routes with these realms.
ip route flush - flush routing tables
this command flushes routes selected by some criteria.
The arguments have the same syntax and semantics as the arguments of
ip route show,
but routing tables are not listed but purged. The only difference is
the default action:
show
dumps all the IP main routing table but
flush
prints the helper page.
With the
-statistics
option, the command becomes verbose. It prints out the number of
deleted routes and the number of rounds made to flush the routing
table. If the option is given
twice,
ip route flush
also dumps all the deleted routes in the format described in the
previous subsection.
ip route get - get a single route
this command gets a single route to a destination and prints its
contents exactly as the kernel sees it.
to ADDRESS (default)
the destination address.
from ADDRESS
the source address.
tos TOS
dsfield TOS
the Type Of Service.
iif NAME
the device from which this packet is expected to arrive.
oif NAME
force the output device on which this packet will be routed.
connected
if no source address
(option from)
was given, relookup the route with the source set to the preferred
address received from the first lookup.
If policy routing is used, it may be a different route.
Note that this operation is not equivalent to
ip route show.
show
shows existing routes.
get
resolves them and creates new clones if necessary. Essentially,
get
is equivalent to sending a packet along this path.
If the
iif
argument is not given, the kernel creates a route
to output packets towards the requested destination.
This is equivalent to pinging the destination
with a subsequent
ip route ls cache,
however, no packets are actually sent. With the
iif
argument, the kernel pretends that a packet arrived from this interface
and searches for a path to forward the packet.
ip rule - routing policy database management
Rules
in the routing policy database control the route selection algorithm.
Classic routing algorithms used in the Internet make routing decisions
based only on the destination address of packets (and in theory,
but not in practice, on the TOS field).
In some circumstances we want to route packets differently depending not only
on destination addresses, but also on other packet fields: source address,
IP protocol, transport protocol ports or even packet payload.
This task is called 'policy routing'.
To solve this task, the conventional destination based routing table, ordered
according to the longest match rule, is replaced with a 'routing policy
database' (or RPDB), which selects routes by executing some set of rules.
Each policy routing rule consists of a
selector
and an
action predicate.
The RPDB is scanned in the order of increasing priority. The selector
of each rule is applied to {source address, destination address, incoming
interface, tos, fwmark} and, if the selector matches the packet,
the action is performed. The action predicate may return with success.
In this case, it will either give a route or failure indication
and the RPDB lookup is terminated. Otherwise, the RPDB program
continues on the next rule.
Semantically, natural action is to select the nexthop and the output device.
At startup time the kernel configures the default RPDB consisting of three
rules:
1.
Priority: 0, Selector: match anything, Action: lookup routing
table
local
(ID 255).
The
local
table is a special routing table containing
high priority control routes for local and broadcast addresses.
Rule 0 is special. It cannot be deleted or overridden.
2.
Priority: 32766, Selector: match anything, Action: lookup routing
table
main
(ID 254).
The
main
table is the normal routing table containing all non-policy
routes. This rule may be deleted and/or overridden with other
ones by the administrator.
3.
Priority: 32767, Selector: match anything, Action: lookup routing
table
default
(ID 253).
The
default
table is empty. It is reserved for some post-processing if no previous
default rules selected the packet.
This rule may also be deleted.
Each RPDB entry has additional
attributes. F.e. each rule has a pointer to some routing
table. NAT and masquerading rules have an attribute to select new IP
address to translate/masquerade. Besides that, rules have some
optional attributes, which routes have, namely
realms.
These values do not override those contained in the routing tables. They
are only used if the route did not select any attributes.
The RPDB may contain rules of the following types:
unicast
- the rule prescribes to return the route found
in the routing table referenced by the rule.
blackhole
- the rule prescribes to silently drop the packet.
unreachable
- the rule prescribes to generate a 'Network is unreachable' error.
prohibit
- the rule prescribes to generate 'Communication is administratively
prohibited' error.
nat
- the rule prescribes to translate the source address
of the IP packet into some other value.
ip rule add - insert a new rule
ip rule delete - delete a rule
type TYPE (default)
the type of this rule. The list of valid types was given in the previous
subsection.
from PREFIX
select the source prefix to match.
to PREFIX
select the destination prefix to match.
iif NAME
select the incoming device to match. If the interface is loopback,
the rule only matches packets originating from this host. This means
that you may create separate routing tables for forwarded and local
packets and, hence, completely segregate them.
tos TOS
dsfield TOS
select the TOS value to match.
fwmark MARK
select the
fwmark
value to match.
priority PREFERENCE
the priority of this rule. Each rule should have an explicitly
set
unique
priority value.
table TABLEID
the routing table identifier to lookup if the rule selector matches.
realms FROM/TO
Realms to select if the rule matched and the routing table lookup
succeeded. Realm
TO
is only used if the route did not select any realm.
nat ADDRESS
The base of the IP address block to translate (for source addresses).
The
ADDRESS
may be either the start of the block of NAT addresses (selected by NAT
routes) or a local host address (or even zero).
In the last case the router does not translate the packets, but
masquerades them to this address.
Warning:
Changes to the RPDB made with these commands do not become active
immediately. It is assumed that after a script finishes a batch of
updates, it flushes the routing cache with
ip route flush cache.
ip rule flush - also dumps all the deleted rules.
This command has no arguments.
ip rule show - list rules
This command has no arguments.
ip maddress - multicast addresses management
maddress
objects are multicast addresses.
ip maddress show - list multicast addresses
dev NAME (default)
the device name.
ip maddress add - add a multicast address
ip maddress delete - delete a multicast address
these commands attach/detach a static link layer multicast address
to listen on the interface.
Note that it is impossible to join protocol multicast groups
statically. This command only manages link layer addresses.
address LLADDRESS (default)
the link layer multicast address.
dev NAME
the device to join/leave this multicast address.
ip mroute - multicast routing cache management
mroute
objects are multicast routing cache entries created by a user level
mrouting daemon (f.e.
pimd
or
mrouted
).
Due to the limitations of the current interface to the multicast routing
engine, it is impossible to change
mroute
objects administratively, so we may only display them. This limitation
will be removed in the future.
ip mroute show - list mroute cache entries
to PREFIX (default)
the prefix selecting the destination multicast addresses to list.
iif NAME
the interface on which multicast packets are received.
from PREFIX
the prefix selecting the IP source addresses of the multicast route.
ip tunnel - tunnel configuration
tunnel
objects are tunnels, encapsulating packets in IPv4 packets and then
sending them over the IP infrastructure.
ip tunnel add - add a new tunnel
ip tunnel change - change an existing tunnel
ip tunnel delete - destroy a tunnel
name NAME (default)
select the tunnel device name.
mode MODE
set the tunnel mode. Three modes are currently available:
ipip, sit and gre.
remote ADDRESS
set the remote endpoint of the tunnel.
local ADDRESS
set the fixed local address for tunneled packets.
It must be an address on another interface of this host.
ttl N
set a fixed TTL
N
on tunneled packets.
N
is a number in the range 1--255. 0 is a special value
meaning that packets inherit the TTL value.
The default value is:
inherit.
tos T
dsfield T
set a fixed TOS
T
on tunneled packets.
The default value is:
inherit.
dev NAME
bind the tunnel to the device
NAME
so that tunneled packets will only be routed via this device and will
not be able to escape to another device when the route to endpoint
changes.
nopmtudisc
disable Path MTU Discovery on this tunnel.
It is enabled by default. Note that a fixed ttl is incompatible
with this option: tunnelling with a fixed ttl always makes pmtu
discovery.
key K
ikey K
okey K
( only GRE tunnels )
use keyed GRE with key
K. K
is either a number or an IP address-like dotted quad.
The
key
parameter sets the key to use in both directions.
The
ikey and okey
parameters set different keys for input and output.
csum, icsum, ocsum
( only GRE tunnels )
generate/require checksums for tunneled packets.
The
ocsum
flag calculates checksums for outgoing packets.
The
icsum
flag requires that all input packets have the correct
checksum. The
csum
flag is equivalent to the combination
icsum ocsum.
seq, iseq, oseq
( only GRE tunnels )
serialize packets.
The
oseq
flag enables sequencing of outgoing packets.
The
iseq
flag requires that all input packets are serialized.
The
seq
flag is equivalent to the combination
iseq oseq.
It isn't work. Don't use it.
ip tunnel show - list tunnels
This command has no arguments.
ip monitor and rtmon - state monitoring
The
ip
utility can monitor the state of devices, addresses
and routes continuously. This option has a slightly different format.
Namely, the
monitor
command is the first in the command line and then the object list follows:
ip monitor [ all |
LISTofOBJECTS ]
OBJECT-LIST
is the list of object types that we want to monitor.
It may contain
link, address and route.
If no
file
argument is given,
ip
opens RTNETLINK, listens on it and dumps state changes in the format
described in previous sections.
If a file name is given, it does not listen on RTNETLINK,
but opens the file containing RTNETLINK messages saved in binary format
and dumps them. Such a history file can be generated with the
rtmon
utility. This utility has a command line syntax similar to
ip monitor.
Ideally,
rtmon
should be started before the first network configuration command
is issued. F.e. if you insert:
rtmon file /var/log/rtmon.log
in a startup script, you will be able to view the full history
later.
Certainly, it is possible to start
rtmon
at any time.
It prepends the history with the state snapshot dumped at the moment
of starting.
HISTORY
ip
was written by Alexey N. Kuznetsov and added in Linux 2.2.
SEE ALSO
tc(8)
IP Command reference ip-cref.ps
IP tunnels ip-cref.ps
