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NAMEroute — manually manipulate the routing tables SYNOPSIS/usr/sbin/route
[-f]
[-n]
[-p
pmtu]
add
[net|host]
destination
[netmask
mask]
gateway
[count]
[source
src] /usr/sbin/route
inet6
[-f]
[-n]
[-p
pmtu]
add
[net|host]
v6destination
[ /
prefix]
v6gateway
[count]
[source
v6src] /usr/sbin/route
[-f]
[-n]
delete
[net|host]
destination
[netmask
mask]
gateway
[count]
[source
src] /usr/sbin/route
inet6
[-f]
[-n]
delete
[net|host]
v6destination
[ /
prefix]
v6gateway
[count]
[source
v6src] /usr/sbin/route
-f
[-n] /usr/sbin/route
inet6
-f
[-n] DESCRIPTIONThe
route
command manipulates the network routing tables manually.
You must have appropriate privileges. SubcommandsThe following subcommands are supported.
- add
Add the specified host or network route to the network routing table.
If the route already exists, a message is printed and nothing changes. - delete
Delete the specified host or network route from the network routing table.
Options and Argumentsroute
recognizes the following options and arguments.
- inet6
Specifies an IPv6 route.
When this option is used, the destination and the gateway must
have IPv6 addresses.
When this option is not used, the command defaults to an IPv4
route and the destination and the gateway must have IPv4 addresses. - -f
Delete all route table entries that specify a remote host for a gateway.
If this is used with one of the subcommands,
the entries are deleted before the subcommand is processed. - -n
Print any host and network addresses in Internet "dot" notation
for IPv4 and in "colon" notation for IPv6, except for the default
network address, which is printed as
default. - -p pmtu
Specifies a path maximum transmission unit (MTU) value for
a static route.
The minimum value allowed is 68 bytes for IPv4 and 1280 bytes for IPv6;
the maximum is the MTU of the outgoing interface for this route.
This option can be applied to both host and network routes. - net
- or
- host
The type of
destination
address.
If this argument is omitted, routes to a particular host are
distinguished from those to a network by interpreting the Internet
address associated with
destination.
For IPv4, if the
destination
has a local address part of
INADDR_ANY(0),
the route is assumed to be to a network;
otherwise, it is treated as a route to a host.
For IPv6, if the
destination
has an address that is less than 128 bits, including any leading
and trailing 0's, the route is assumed to be a network;
otherwise, it is treated as a route to a host.
An exception is the IPv6 "Unspecified Address", typically
represented as
::,
which is always interpreted as the
default network route. - destination
(inet only)
The destination host system where the packets will be routed.
destination
can be one of the following:
A host name (the official name or an alias, see
gethostent(3N)). A network name (the official name or an alias, see
getnetent(3N)). An Internet address in "dot" notation (see
inet(3N)). The keyword
default,
which signifies the wildcard gateway route (see
routing(7)).
- v6destination
(inet6 only)
The destination host system where the packets will be routed.
v6destination
can be one of the following:
A host name (the official name or an alias, see
getaddrinfo(3N)). An IPv6 address in "colon" notation (see
inet6(3N)). The keyword
default,
which signifies the wildcard gateway route.
- prefix
(inet6 only)
The
prefix
is an integer between 0 and 128 inclusive.
It specifies how many of the leftmost contiguous bits
of the v6destination address comprise the prefix.
Its format is similar to the CIDR notation in IPv4.
A
prefix
of 0 would be a default route.
If the
prefix
is omitted when adding a network route,
then the
prefix
would be 64 by default.
It is advisable to specify the
prefix
when an IPv6 network route is added.
The
prefix
option can be applied to network routes only. - netmask mask
(inet only)
The mask that will be bit-wise ANDed with
destination
to yield a net address where the packets will be routed.
mask
can be specified as a single hexadecimal number with a leading
0x,
with a "dot-notation" Internet address,
or with a pseudo-network name listed in the network table (see
networks(4)).
The length of the
mask,
which is the number of contiguous 1's starting from the left-most
bit position of the 32-bit field, can be shorter than the default
network mask for the
destination
address. (See
routing(7)).
If the
netmask
option is not given,
mask
for the route will be derived from the
netmasks
associated with the local interfaces. (See
ifconfig(1M)).
mask
will be defaulted to the longest
netmask
of those local interfaces that have the same network address.
If there is not any local interface that has the same network
address, then
mask
will default to the default value of network mask of
destination. - gateway
(inet only)
The gateway through which the destination is reached.
gateway
can be one of the following:
A host name (the official name or an alias, see
gethostent(3N)). An Internet address in "dot" notation (see
inet(3N)).
- v6gateway
(inet6 only)
The gateway through which the destination is reached.
v6gateway
can be one of the following:
- count
An integer that indicates whether the gateway is a remote
host or the local host.
If the route leads to a destination through a remote gateway,
count
should be a number greater than 0.
If the route leads to
destination
and the gateway is the local host,
count
should be 0.
The default for
count
is zero.
The result is not defined if
count
is negative. - source src
(inet only)
The specified source address.
This option allows traffic to be directed to a selected
interface instead of to the system default.
When the Strong ES Model is set to 1, this option allows going out of
an interface that would normally be blocked.
Note that the gateway and source must be in the same subnet. src
can be one of the following:
A host name (the official name or an alias, see
gethostent(3N)). An Internet address in "dot" notation (see
inet(3N)).
- source v6src
(inet6 only)
The specified source address.
This option allows traffic to be directed to a selected
interface instead of to the system default.
Note that the
gateway and source must be in the same subnet. v6src
can be one of the following:
OperationAll symbolic names specified for a
destination
or
gateway
are looked up first as a host name using
gethostbyname()
for IPv4 and
getaddrinfo()
for IPv6;
if the host name is not found, the
destination
is searched for as a network name using
getnetbyname()
for IPv4 only.
destination
and
gateway
can be in "dot" notation (see
inet(3N)).
v6destination
and
v6gateway
can be in "colon" notation (see
inet6(3N)). If the
-n
option is not specified, any host and network addresses are
displayed symbolically according to the name returned by
gethostbyaddr()
and
getnetbyaddr(),
respectively, except for the default network address
(printed as
default)
and addresses that have unknown names.
Addresses with unknown names are printed in Internet "dot" notation (see
inet(3N)). If the
-n
option is specified,
any host and network addresses are printed in Internet "dot" notation
except for the default network address which is printed as
default. If the
-f
option is specified,
route
deletes all route table entries
that specify a remote host for a gateway.
If it is used with one of the subcommands described above,
the entries are deleted before the subcommand is processed. Path MTU Discovery is a technique for discovering the maximum size of
an IP datagram that can be sent on an internet path without causing
datagram fragmentation in the intermediate routers.
In essence, a source host that utilizes this technique
initially sends out datagrams up to the the size of the outgoing interface.
The Don't Fragment (DF) bit in the IP datagram header is set.
As an intermediate router that supports Path MTU Discovery
receives a datagram that is too large to be forwarded in one piece
to the next-hop router and the DF bit is set,
the router will discard the datagram
and send an ICMP Destination Unreachable message
with a code meaning "fragmentation needed and DF set".
The ICMP message will also contain the MTU of the next-hop router.
When the source host receives the ICMP message,
it reduces the path MTU of the route to the MTU in the ICMP message.
With this technique,
the host route in the source host for this path will contain the proper MTU. The
-p
pmtu
option is useful only if you know the network environment well
enough to enter an appropriate
pmtu
for a host or network route.
IP will fragment a datagram to the
pmtu
specified for the route on the local host
before sending the datagram out to the remote.
It will avoid fragmentation by routers along the path, if the
pmtu
specified in the
route
command is correct. ping
can be used to find the
pmtu
information for the route to a remote host.
The
pmtu
information in the routing table can be displayed with the
netstat -r
command (see
netstat(1)). The loopback interface
(lo0)
is automatically configured when the
system boots with the TCP/IP software. For IPv4, the default IP address and
netmask of the loopback interface are 127.0.0.1 and 255.0.0.0, respectively.
For IPv6, the default IP address and prefix of the loopback interface are
::1 and 128, respectively. When
lo0
is configured,
the 127.0.0.0 loopback route for IPv4 and
the ::1 loopback route for IPv6
are set up automatically
so that packets for any 127.*.*.* address and ::1 will loop back
to the local host.
Users cannot add or delete any 127.*.*.* or ::1 loopback routes. IPv6 OperationThe keyword
inet6
is required for adding or deleting IPv6 routes. Examples route inet6 add 2345::1 4444::3 route inet6 add net 2222::/64
4567::8 1
route inet6 delete net 2222::/64
4567::8 1
Outputadd destination: gateway gateway
The specified route is being added to the tables.
delete destination: gateway gateway
The specified route is being deleted from the tables.
FlagsThe values of the
count
and
destination
type fields in the
route
command determine the presence of the
G
and
H
flags in the
netstat -r
display and thus the route type, as shown in the following table. DIAGNOSTICSThe following error diagnostics can be displayed:
add a route that already exists The specified entry is already in the routing table.
delete a route that does not exist The specified route was not in the routing table.
cannot update loopback route Routes for any 127.*.*.* loopback destination cannot be added or deleted. WARNINGSReciprocal
route
commands must be executed on the local host,
the destination host, and all intermediate hosts
if routing is to succeed in the cases of virtual circuit connections
or bidirectional datagram transfers. The
HP-UX
implementation of
route
does not presently support a
change
subcommand. AUTHORroute
was developed by the University of California, Berkeley. SEE ALSOnetstat(1),
ifconfig(1M),
ndd(1M),
ping(1M),
getsockopt(2),
recv(2),
send(2),
getaddrinfo(3N),
gethostent(3N),
getnetent(3N),
inet(3N),
inet6(3N),
routing(7). |
