route(1M)route(1M)NAMEroute - manually manipulate the routing tables
SYNOPSIS
pmtu] destination mask] gateway [count] src]
pmtu] v6destination [ / prefix] v6gateway [count] v6src]
destination mask] gateway [count] src]
v6destination [ / prefix] v6gateway [count] v6src]
DESCRIPTION
The command manipulates the network routing tables manually. You must
have appropriate privileges.
Subcommands
The following subcommands are supported.
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 the specified host or network route from the network
routing table.
Options and Arguments
recognizes the following options and arguments.
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.
Deletes all route table entries added through route command or
through an ioctl. If this is used with one of
the subcommands, the entries are deleted before
the subcommand is processed.
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
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 maxi‐
mum is the MTU of the outgoing interface for this
route. This option can be applied to both host
and network routes.
or
The type of destination address. If this argu‐
ment is omitted, routes to a par‐
ticular 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 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 geth‐
ostent(3N)).
· A network name (the offi‐
cial name or an alias, see
getnetent(3N)).
· An Internet address in
"dot" notation (see
inet(3N)).
· The keyword 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 which signifies
the wildcard gateway route.
prefix (inet6 only) The prefix is an inte‐
ger between 0 and 128 inclusive.
It specifies how many of the left‐
most contiguous bits of the v6des‐
tination address comprise the pre‐
fix. 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.
(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 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 option is not
given, mask for the route will be
derived from the associated with
the local interfaces. (See ifcon‐
fig(1M)). mask will be defaulted
to the longest of those local
interfaces that have the same net‐
work 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 follow‐
ing:
· A host name (the official
name or an alias, see geth‐
ostent(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 follow‐
ing:
· A host name (the official
name or an alias, see
getaddrinfo(3N)).
· An IPv6 address in "colon"
notation (see inet6(3N)).
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.
(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 geth‐
ostent(3N)).
· An Internet address in
"dot" notation (see
inet(3N)).
(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:
· A host name (the official
name or an alias, see
getaddrinfo(3N)).
· An IPv6 address in "colon"
notation (see inet6(3N)).
(It is supported only when HP-UX Secure Resource
Partitions is installed
and enabled with system style con‐
tainers (refer to srp(5))).
This option is used to add a spe‐
cial route to local destinations
within the host. In order to push
local-local communication on wire,
user needs to add a special route
to make a directly reachable local
destination to reach indirectly via
a gateway. (For more information,
see the section below).
The force option is valued only
while adding route to one of local
destination on the system.
Operation
All symbolic names specified for a destination or gateway
are looked up first as a host name using for IPv4 and for
IPv6; if the host name is not found, the destination is
searched for as a network name using for IPv4 only. des‐
tination and gateway can be in "dot" notation (see
inet(3N)). v6destination and v6gateway can be in "colon"
notation (see inet6(3N)).
If the option is not specified, any host and network
addresses are displayed symbolically according to the
name returned by and respectively, except for the default
network address (printed as and addresses that have
unknown names. Addresses with unknown names are printed
in Internet "dot" notation (see inet(3N)).
If the option is specified, any host and network
addresses are printed in Internet "dot" notation except
for the default network address which is printed as
If the option is specified, 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 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 command is correct.
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 command (see netstat(1)).
The loopback interface 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 is configured, the 127.0.0.0 loopback route for IPv4
and the ::1 loopback route for IPv6 are set up automati‐
cally 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 Operation
The keyword is required for adding or deleting IPv6
routes.
Examples
add a direct IPv6 host route
add an indirect IPv6 (sub)network route
delete an indirect IPv6 (sub)network route
Output
The specified route is being added to the tables.
The specified route is being deleted from the
tables.
Adding Special Routes
Special routes are the routes added to reach one of the
local destinations via a gateway. By default, traffic
between local-local destinations are never pushed on wire
because both the end points are directly reachable on the
system.
In order to trace this local-local traffic on wire, users
can alter the above default behavior. In this scenario,
traffic between two local destinations is routed to a
external gateway and then it gets routed back to the same
host.
Examples:
Settings required to push the communication between two
local
destination lan1 and lan2.
To push traffic destined to lan1 on wire, set force flag
on lan1 using
ifconfig (1m):
Similarly set force flag on lan2:
Add a special "host/net/default" routes to each local
destination via remote gateway.
Adding host routes to local destinations:
Adding net routes to local destinations:
Adding default routes to local destinations:
Flags
The values of the count and destination type fields in
the command determine the presence of the and flags in
the display and thus the route type, as shown in the fol‐
lowing table.
Count Destination Type Flags Route Type
──────────────────────────────────────────────────────────────────
=0 network U Route to a network directly
from the local host
>0 network UG Route to a network through a
remote host gateway
=0 host UH Route to a remote host
directly from the local host
>0 host UGH Route to a remote host through
a remote host gateway
=0 default U Wildcard route directly from
the local host
>0 default UG Wildcard route through a
remote host gateway
──────────────────────────────────────────────────────────────────
DIAGNOSTICS
The following error diagnostics can be displayed:
The specified entry is already in the routing table.
The specified route was not in the routing table.
Routes for any 127.*.*.* loopback destination cannot be
added or deleted.
WARNINGS
Reciprocal commands must be executed on the local host,
the destination host, and all intermediate hosts if rout‐
ing is to succeed in the cases of virtual circuit connec‐
tions or bidirectional datagram transfers.
The HP-UX implementation of does not presently support a
subcommand.
AUTHOR
was developed by the University of California, Berkeley.
FILESSEE ALSOnetstat(1), ifconfig(1M), ndd(1M), ping(1M), getsock‐
opt(2), recv(2), send(2), getaddrinfo(3N), gethos‐
tent(3N), getnetent(3N), inet(3N), inet6(3N), routing(7),
route(7P).
route(1M)
