from small one page howto to huge articles all in one place
 

search text in:





Poll
Which kernel version do you use?





poll results

Last additions:
using iotop to find disk usage hogs

using iotop to find disk usage hogs

words:

887

views:

27456

userrating:

average rating: 1.5 (36 votes) (1=very good 6=terrible)


May 25th. 2007:
Words

486

Views

85373

why adblockers are bad


Workaround and fixes for the current Core Dump Handling vulnerability affected kernels

Workaround and fixes for the current Core Dump Handling vulnerability affected kernels

words:

161

views:

36640

userrating:

average rating: 1.3 (15 votes) (1=very good 6=terrible)


April, 26th. 2006:

Druckversion
You are here: manpages





ROUTE

Section: Linux System Administrator's Manual (8)
Updated: 2008-10-03
Index Return to Main Contents
 

NAME

route - show / manipulate the IP routing table  

SYNOPSIS

route [-CFvnee]
route
[-v] [-A family] add [-net|-host] target [netmask Nm] [gw Gw] [metric N] [mss M] [window W] [irtt I] [reject] [mod] [dyn] [reinstate] [[dev] If]
route
[-v] [-A family] del [-net|-host] target [gw Gw] [netmask Nm] [metric N] [[dev] If]
route
[-V] [--version] [-h] [--help]
 

DESCRIPTION

Route manipulates the kernel's IP routing tables. Its primary use is to set up static routes to specific hosts or networks via an interface after it has been configured with the ifconfig(8) program.

When the add or del options are used, route modifies the routing tables. Without these options, route displays the current contents of the routing tables.

 

OPTIONS

-A family
use the specified address family (eg `inet'; use `route --help' for a full list).

-F
operate on the kernel's FIB (Forwarding Information Base) routing table. This is the default.
-C
operate on the kernel's routing cache.

-v
select verbose operation.
-n
show numerical addresses instead of trying to determine symbolic host names. This is useful if you are trying to determine why the route to your nameserver has vanished.
-e
use netstat(8)-format for displaying the routing table. -ee will generate a very long line with all parameters from the routing table.

del
delete a route.
add
add a new route.
target
the destination network or host. You can provide IP addresses in dotted decimal or host/network names.
-net
the target is a network.
-host
the target is a host.
netmask NM
when adding a network route, the netmask to be used.
gw GW
route packets via a gateway. NOTE: The specified gateway must be reachable first. This usually means that you have to set up a static route to the gateway beforehand. If you specify the address of one of your local interfaces, it will be used to decide about the interface to which the packets should be routed to. This is a BSDism compatibility hack.
metric M
set the metric field in the routing table (used by routing daemons) to M.
mss M
sets MTU (Maximum Transmission Unit) of the route to M bytes. Note that the current implementation of the route command does not allow the option to set the Maximum Segment Size (MSS).
window W
set the TCP window size for connections over this route to W bytes. This is typically only used on AX.25 networks and with drivers unable to handle back to back frames.
irtt I
set the initial round trip time (irtt) for TCP connections over this route to I milliseconds (1-12000). This is typically only used on AX.25 networks. If omitted the RFC 1122 default of 300ms is used.
reject
install a blocking route, which will force a route lookup to fail. This is for example used to mask out networks before using the default route. This is NOT for firewalling.
mod, dyn, reinstate
install a dynamic or modified route. These flags are for diagnostic purposes, and are generally only set by routing daemons.
dev If
force the route to be associated with the specified device, as the kernel will otherwise try to determine the device on its own (by checking already existing routes and device specifications, and where the route is added to). In most normal networks you won't need this.

If dev If is the last option on the command line, the word dev may be omitted, as it's the default. Otherwise the order of the route modifiers (metric - netmask - gw - dev) doesn't matter.

 

EXAMPLES

route add -net 127.0.0.0 netmask 255.0.0.0 dev lo
adds the normal loopback entry, using netmask 255.0.0.0 and associated with the "lo" device (assuming this device was previously set up correctly with ifconfig(8)).

route add -net 192.56.76.0 netmask 255.255.255.0 dev eth0
adds a route to the local network 192.56.76.x via "eth0". The word "dev" can be omitted here.

route del default
deletes the current default route, which is labeled "default" or 0.0.0.0 in the destination field of the current routing table.

route add default gw mango-gw
adds a default route (which will be used if no other route matches). All packets using this route will be gatewayed through "mango-gw". The device which will actually be used for that route depends on how we can reach "mango-gw" - the static route to "mango-gw" will have to be set up before.

route add ipx4 sl0
Adds the route to the "ipx4" host via the SLIP interface (assuming that "ipx4" is the SLIP host).

route add -net 192.57.66.0 netmask 255.255.255.0 gw ipx4
This command adds the net "192.57.66.x" to be gatewayed through the former route to the SLIP interface.

route add -net 224.0.0.0 netmask 240.0.0.0 dev eth0
This is an obscure one documented so people know how to do it. This sets all of the class D (multicast) IP routes to go via "eth0". This is the correct normal configuration line with a multicasting kernel.

route add -net 10.0.0.0 netmask 255.0.0.0 reject
This installs a rejecting route for the private network "10.x.x.x."

 

OUTPUT

The output of the kernel routing table is organized in the following columns
Destination
The destination network or destination host.
Gateway
The gateway address or '*' if none set.
Genmask
The netmask for the destination net; '255.255.255.255' for a host destination and '0.0.0.0' for the default route.
Flags
Possible flags include
U (route is up)
H (target is a host)
G (use gateway)
R (reinstate route for dynamic routing)
D (dynamically installed by daemon or redirect)
M (modified from routing daemon or redirect)
A (installed by addrconf)
C (cache entry)
! (reject route)
Metric
The 'distance' to the target (usually counted in hops). It is not used by recent kernels, but may be needed by routing daemons.
Ref
Number of references to this route. (Not used in the Linux kernel.)
Use
Count of lookups for the route. Depending on the use of -F and -C this will be either route cache misses (-F) or hits (-C).
Iface
Interface to which packets for this route will be sent.
MSS
Default maximum segment size for TCP connections over this route.
Window
Default window size for TCP connections over this route.
irtt
Initial RTT (Round Trip Time). The kernel uses this to guess about the best TCP protocol parameters without waiting on (possibly slow) answers.
HH (cached only)
The number of ARP entries and cached routes that refer to the hardware header cache for the cached route. This will be -1 if a hardware address is not needed for the interface of the cached route (e.g. lo).
Arp (cached only)
Whether or not the hardware address for the cached route is up to date.

 

FILES

/proc/net/ipv6_route
/proc/net/route
/proc/net/rt_cache

 

SEE ALSO

ifconfig(8), netstat(8), arp(8), rarp(8)

 

HISTORY

Route for Linux was originally written by Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org> and then modified by Johannes Stille and Linus Torvalds for pl15. Alan Cox added the mss and window options for Linux 1.1.22. irtt support and merged with netstat from Bernd Eckenfels.  

AUTHOR

Currently maintained by Phil Blundell <Philip.Blundell@pobox.com> and Bernd Eckenfels <net-tools@lina.inka.de>.


 

Index

NAME
SYNOPSIS
DESCRIPTION
OPTIONS
EXAMPLES
OUTPUT
FILES
SEE ALSO
HISTORY
AUTHOR


Please read "Why adblockers are bad".



Other free services
toURL.org
Shorten long
URLs to short
links like
http://tourl.org/2
tourl.org
.
Reverse DNS lookup
Find out which hostname(s)
resolve to a
given IP or other hostnames for the server
www.reversednslookup.org
rdf newsfeed | rss newsfeed | Atom newsfeed
- Powered by LeopardCMS - Running on Gentoo -
Copyright 2004-2013 Sascha Nitsch Unternehmensberatung UG(haftungsbeschränkt)
Valid XHTML1.1 : Valid CSS : buttonmaker
- Level Triple-A Conformance to Web Content Accessibility Guidelines 1.0 -
- Copyright and legal notices -
Time to create this page: 20.1 ms