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1. UNIX for Beginners Questions & Answers
Dear friends
I use RedHat 6.5, which sets the gateway in the configuration file / etc / sysconfig / network as GATEWAY = 192.168.1.26, and the gateway in the configuration file / etc / sysconfig / network-scripts / ifcfg-eth11 as GATEWAY = 192.168.1.256. The two gateways are different.... (6 Replies)
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2. Red Hat
Hi..I have to change default gateway in my linux machine. Its OS is RHEL6.
I followed following steps.
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2.delete that gateway with command
route del default gw x.x.x.x eth2
3.Add new gatewy with command below
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3. Red Hat
Hi,
Here is the issue: There are 2 identical systems in the same subnet here. They can ping and ssh each other. One can ping the default gateway and one can not with error '... icmp_seq Destination Host Unreachable'. I can't find any difference between the two systems in terms of network... (4 Replies)
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4. Linux
Dear Sir
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5. HP-UX
where in configuration files can i modify default gateway in hp-ux11iv3 (5 Replies)
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6. AIX
Hi,
I have two interfaces on m AIX 5.3 box. One going to 192.168.1.x and it has a gateway of 192.168.1.1.
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7. IP Networking
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8. Solaris
my actual default gatewas IP is:
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9. HP-UX
I am using HP-UX 11i and I need to add another default gateway.
how can I do that ? (3 Replies)
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route(1M) route(1M)
NAME
route - 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 pro-
cessed.
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 maximum 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 argument is omitted, routes to a particular host are distinguished from those to a net-
work 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:
o A host name (the official name or an alias, see gethostent(3N)).
o A network name (the official name or an alias, see getnetent(3N)).
o An Internet address in "dot" notation (see inet(3N)).
o 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 follow-
ing:
o A host name (the official name or an alias, see getaddrinfo(3N)).
o An IPv6 address in "colon" notation (see inet6(3N)).
o The keyword 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.
(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 ifconfig(1M)). mask will be defaulted to the longest 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:
o A host name (the official name or an alias, see gethostent(3N)).
o 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:
o A host name (the official name or an alias, see getaddrinfo(3N)).
o 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 destina-
tion 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 nor-
mally be blocked. Note that the gateway and source must be in the same subnet.
src can be one of the following:
o A host name (the official name or an alias, see gethostent(3N)).
o 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:
o A host name (the official name or an alias, see getaddrinfo(3N)).
o An IPv6 address in "colon" notation (see inet6(3N)).
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. destination 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 respec-
tively, 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 sub-
commands 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 con-
tain 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 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 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.
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 following 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 routing is to succeed in the
cases of virtual circuit connections or bidirectional datagram transfers.
The HP-UX implementation of does not presently support a subcommand.
AUTHOR
was developed by the University of California, Berkeley.
FILES
SEE ALSO
netstat(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), route(7P).
route(1M)