Networking section - Revision history

Saruman!: Undo spamming

2010-03-29T10:03:46Z

Undo spamming

← Older revision		Revision as of 10:03, 29 March 2010
Line 4:		Line 4:
	# manually adding a route at the command prompt: this means that the machine will "understand" the route for as long as it is running. However, when you reboot the machine, it will have "forgotten" the route. This is called a non-persistent route.		# manually adding a route at the command prompt: this means that the machine will "understand" the route for as long as it is running. However, when you reboot the machine, it will have "forgotten" the route. This is called a non-persistent route.
	# adding a route to the networking configuration files, so that it will be in place regardless of reboots or network restarts. This is called a persistent route.		# adding a route to the networking configuration files, so that it will be in place regardless of reboots or network restarts. This is called a persistent route.
	~~[http://www.bestessays.com buy papers]~~
	===Manipulating non-persistent routes===		===Manipulating non-persistent routes===
	From the days of yore, the venerable ''route'' command enables us to view, add, change and delete routes. Its most known use is for printing the current routing table:		From the days of yore, the venerable ''route'' command enables us to view, add, change and delete routes. Its most known use is for printing the current routing table:

Kimberly: /* Routes under Debian */

2010-03-23T16:04:00Z

Routes under Debian

← Older revision		Revision as of 16:04, 23 March 2010
Line 4:		Line 4:
	# manually adding a route at the command prompt: this means that the machine will "understand" the route for as long as it is running. However, when you reboot the machine, it will have "forgotten" the route. This is called a non-persistent route.		# manually adding a route at the command prompt: this means that the machine will "understand" the route for as long as it is running. However, when you reboot the machine, it will have "forgotten" the route. This is called a non-persistent route.
	# adding a route to the networking configuration files, so that it will be in place regardless of reboots or network restarts. This is called a persistent route.		# adding a route to the networking configuration files, so that it will be in place regardless of reboots or network restarts. This is called a persistent route.
			[http://www.bestessays.com buy papers]
	===Manipulating non-persistent routes===		===Manipulating non-persistent routes===
	From the days of yore, the venerable ''route'' command enables us to view, add, change and delete routes. Its most known use is for printing the current routing table:		From the days of yore, the venerable ''route'' command enables us to view, add, change and delete routes. Its most known use is for printing the current routing table:

Saruman!: Reverted edits by 83.233.30.77 (Talk); changed back to last version by Saruman!

2009-02-12T21:06:44Z

Reverted edits by 83.233.30.77 (Talk); changed back to last version by Saruman!

← Older revision		Revision as of 21:06, 12 February 2009
Line 1:		Line 1:
	~~http~~:~~//hyves~~.~~mn/dsee/bee~~-~~pollen~~.~~html bee pollen~~		==Routes under Debian==
	~~http://hyves~~.~~mn/dsee/bee~~-~~brooch~~.~~html bee brooch~~
	~~http://hyves~~.~~mn/dsee/bedwetting-diapers~~.~~html bedwetting diapers~~		When you need to add a networking route, there generally are two ways to do it:
	~~http://hyves~~.~~mn/dsee/bedroom-furniture-stores~~.~~html bedroom furniture stores~~		# manually adding a route at the command prompt: this means that the machine will "understand" the route for as long as it is running. However, when you reboot the machine, it will have "forgotten" the route. This is called a non-persistent route.
	~~http://hyves~~.~~mn/dsee/bedroom-furniture-store~~.~~html bedroom furniture store~~		# adding a route to the networking configuration files, so that it will be in place regardless of reboots or network restarts. This is called a persistent route.
	~~http://hyves~~.~~mn/dsee/bedroom-furniture~~-~~set~~.~~html bedroom furniture set~~
	~~http~~:~~//hyves~~.~~mn/dsee/bedroom-furniture-sale~~.~~html bedroom furniture sale~~		===Manipulating non-persistent routes===
	~~http~~:/~~/hyves~~.~~mn/dsee/bedroom-furniture-modern~~.~~html bedroom furniture modern~~		From the days of yore, the venerable ''route'' command enables us to view, add, change and delete routes. Its most known use is for printing the current routing table:
	~~http:~~/~~/hyves~~.~~mn/dsee/bedroom-furniture-contemporary~~.~~html bedroom furniture contemporary~~		#route -n
	~~http:~~/~~/hyves~~.~~mn/dsee/bedding-ralph-lauren~~.~~html bedding ralph lauren~~		Kernel IP routing table
	~~http://hyves~~.~~mn/dsee/bed-sizes~~.~~html bed sizes~~		Destination Gateway Genmask Flags Metric Ref Use Iface
	~~http~~:/~~/hyves~~.~~mn/dsee/bed-frame~~.~~html bed frame~~		192.168.70.0 212.214.172.50 255.255.255.0 UG 0 0 0 eth1
	~~http~~:~~//hyves~~.~~mn/dsee/bed-bath-beyond-wedding-registry~~.~~html bed bath beyond wedding registry~~		192.168.67.0 * 255.255.255.0 U 0 0 0 eth0
	~~http://hyves~~.mn/~~dsee/bed~~.~~html bed~~		212.214.172.0 * 255.255.255.0 U 0 0 0 eth1
	~~http~~://~~hyves~~.mn/~~dsee/becks-beer~~.~~html becks beer~~		default 212.214.172.1 0.0.0.0 UG 0 0 0 eth1
	~~http://hyves~~.mn/~~dsee/beckman~~.~~html beckman~~		The addition of -n makes sure the ''route'' command does not try to substitute DNS names for IP addresses it knows.
	~~http~~:~~//hyves.mn/dsee/because~~-i-~~got~~-~~high~~.~~html because i got high~~		The second most used incarnation of ''route'' lies in the addition of a route, as has happened in the previous example. The route was added to the routing table using something like this:
	~~http:~~//~~hyves.mn~~/~~dsee/bebo~~-~~layouts~~.~~html bebo layouts~~		#route add -net 192.168.70.0 netmask 255.255.255.0 gw 212.214.172.40
	~~http://hyves~~.~~mn/dsee/beaverhunt~~.~~html beaverhunt~~		However, there is a newer command available to us, that gives us a bit more options (however, at the cost of losing the well-known output format): this is the ''ip'' command, which is part of the [[Essential_system_software\|essential]] ''iproute2'' package:
	~~http:/~~/~~hyves.mn~~/~~dsee~~/~~beauty~~-~~tips~~.~~html beauty tips~~		#ip route show
			192.168.70.0/24 via 212.214.172.50 dev eth1 src 192.168.67.10
			192.168.67.0/24 dev eth0 proto kernel scope link src 192.168.67.10
			212.214.172.0/24 dev eth1 proto kernel scope link src 212.214.172.50
			default via 212.214.172.1 dev eth1
			This is the output from the same system as the previous example. However, we see something interesting here: "ip" is capable of adding extra information to the route, like the first line shows (it's using "via"). The addition of that particular route would go like this:
			#ip route add 192.168.70.0/24 via 212.214.172.50 src 192.168.67.10

			Ofcourse, being capable of adding routes means we also need to be capable of deleting them:
			#route del -net 192.168.70.0 netmask 255.255.255.0
			#ip route del 192.168.70.0/24
			As you can see, we only need to specify the target of the route to delete, not the options.

			===Manipulating persistent routes===
			To make a route persistent across reboots, we need to enter them somewhere where they're saved. There are many possible routes available, but the two that fit Debian the most are the following:

			'''A)''' You could add the route addition command to the ''/etc/network/interfaces'' file; let the command itself be preceeded with the keyword "up" to signal the networking scripts that the command must be executed when an interface is brought "up"; the line could look like this (just as the examples from the preceeding section):
			<pre>
			# Internet interface
			auto eth1
			iface eth1 inet dhcp
			up ip route add 192.168.70.0/24 via 212.214.172.50 src 192.168.67.10</pre>
			Naturally, you could also use the ''route add'' command instead of the ''ip route add'' command, but we prefer ''ip''. Note: it matters --where-- in the ''interfaces'' file you put this line: it should be put in the same stanza as the interface it operates on. In this example, the external interface of the server is 212.214.172.50, which belongs with interface ''eth1''. Therefore, the "up" line appears in the stanza for ''eth1''.

			'''B)''' You could create a script that sets the route(s), and put it in the directory ''/etc/network/if-up.d''. Since all scripts that reside there get called when any interface goes "up", your route setting script would be called when ''any'' interface comes up, including ''lo''. This in turn means that a script for setting a route that belongs with a particular interface, should check on invocation which is the interface that goes up. At this moment in time, we don't employ any such script, so no example here, but if you look at the existing scripts in ''/etc/network/if-up.d'' you'll see how other programmers have done this.

	==DNS resolution under Debian==		==DNS resolution under Debian==

83.233.30.77: /* Routes under Debian */

2009-02-12T20:56:23Z

Routes under Debian

← Older revision		Revision as of 20:56, 12 February 2009
Line 1:		Line 1:
	~~==Routes under Debian==~~		http://hyves.mn/dsee/bee-pollen.html bee pollen
			http://hyves.mn/dsee/bee-brooch.html bee brooch
	~~When you need to add a networking route, there generally are two ways to do it~~:		http://hyves.mn/dsee/bedwetting-diapers.html bedwetting diapers
	~~# manually adding a route at the command prompt~~: ~~this means that the machine will "understand" the route for as long as it is running~~. ~~However, when you reboot the machine, it will have "forgotten" the route. This is called a non~~-~~persistent route~~.		http://hyves.mn/dsee/bedroom-furniture-stores.html bedroom furniture stores
	~~# adding a route to the networking configuration files, so that it will be in place regardless of reboots or network restarts~~. ~~This is called a persistent route~~.		http://hyves.mn/dsee/bedroom-furniture-store.html bedroom furniture store
			http://hyves.mn/dsee/bedroom-furniture-set.html bedroom furniture set
	~~===Manipulating non~~-~~persistent routes===~~		http://hyves.mn/dsee/bedroom-furniture-sale.html bedroom furniture sale
	~~From the days of yore, the venerable ''route'' command enables us to view, add, change and delete routes~~. ~~Its most known use is for printing the current routing table:~~		http://hyves.mn/dsee/bedroom-furniture-modern.html bedroom furniture modern
	~~#route~~ -n		http://hyves.mn/dsee/bedroom-furniture-contemporary.html bedroom furniture contemporary
	~~Kernel IP routing table~~		http://hyves.mn/dsee/bedding-ralph-lauren.html bedding ralph lauren
	~~Destination Gateway Genmask Flags Metric Ref Use Iface~~		http://hyves.mn/dsee/bed-sizes.html bed sizes
	~~192.168.70.0 212.214.172~~.~~50 255.255.255.0 UG 0 0 0 eth1~~		http://hyves.mn/dsee/bed-frame.html bed frame
	~~192~~.~~168~~.~~67.0 * 255.255.255.0 U 0 0 0 eth0~~		http://hyves.mn/dsee/bed-bath-beyond-wedding-registry.html bed bath beyond wedding registry
	~~212~~.~~214.172.0 * 255.255.255~~.~~0 U 0 0 0 eth1~~		http://hyves.mn/dsee/bed.html bed
	~~default 212~~.~~214.172.1 0.0.0.0 UG 0 0 0 eth1~~		http://hyves.mn/dsee/becks-beer.html becks beer
	~~The addition of~~ -~~n makes sure the ''route'' command does not try to substitute DNS names for IP addresses it knows~~.		http://hyves.mn/dsee/beckman.html beckman
	~~The second most used incarnation of ''route'' lies in the addition of a route, as has happened in the previous example~~. ~~The route was added to the routing table using something like this:~~		http://hyves.mn/dsee/because-i-got-high.html because i got high
	~~#route add~~ -~~net 192.168.70.0 netmask 255.255~~.~~255.0 gw 212.214.172.40~~		http://hyves.mn/dsee/bebo-layouts.html bebo layouts
	~~However, there is a newer command available to us, that gives us a bit more options (however, at the cost of losing the well-known output format)~~: ~~this is the ''ip'' command, which is part of the [[Essential_system_software\|essential]] ''iproute2'' package:~~		http://hyves.mn/dsee/beaverhunt.html beaverhunt
	~~#ip route show~~		http://hyves.mn/dsee/beauty-tips.html beauty tips
	~~192~~.~~168.70.0~~/~~24 via 212~~.~~214.172.50 dev eth1 src 192.168.67.10~~
	~~192~~.~~168.67.0~~/~~24 dev eth0 proto kernel scope link src 192~~.~~168.67.10~~
	~~212~~.~~214.172.0~~/~~24 dev eth1 proto kernel scope link src 212.214.172~~.50
	~~default via 212~~.~~214.172~~.~~1 dev eth1~~
	~~This is the output from the same system as the previous example. However, we see something interesting here~~: ~~"ip" is capable of adding extra information to the route, like the first line shows (it's using "via")~~. ~~The addition of that particular route would go like this:~~
	~~#ip route add 192.168.70.0~~/~~24 via 212~~.~~214.172.50 src 192.168.67.10~~

	~~Ofcourse, being capable of adding routes means we also need to be capable of deleting them~~:
	~~#route del~~ -~~net 192.168.70.0 netmask 255.255.255~~.0
	~~#ip route del 192~~.~~168.70.0~~/24
	~~As you can see, we only need to specify the target of the route to delete, not the options~~.

	~~===Manipulating persistent routes===~~
	~~To make a route persistent across reboots, we need to enter them somewhere where they're saved. There are many possible routes available, but the two that fit Debian the most are the following~~:

	~~'''A)''' You could add the route addition command to the ''/etc~~/~~network~~/interfaces'' file; let the command itself be preceeded with the keyword "up" to signal the networking scripts that the command must be executed when an interface is brought "up"; the line could look like this (just as the examples from the preceeding section):
	~~<pre>~~
	~~# Internet interface~~
	~~auto eth1~~
	~~iface eth1 inet dhcp~~
	~~up ip route add 192.168.70~~.0/~~24 via 212.214.172.50 src 192.168.67.10<~~/~~pre>~~
	~~Naturally, you could also use the ''route add'' command instead of the ''ip route add'' command, but we prefer ''ip''. Note: it matters~~ --~~where~~-- in the ''interfaces'' file you put this line: it should be put in the same stanza as the interface it operates on. In this example, the external interface of the server is 212.214.172.50, which belongs with interface ''eth1''. Therefore, the "up" line appears in the stanza for ''eth1''.

	~~'''B)''' You could create a script that sets the route(s), and put it in the directory ''~~/~~etc~~/~~network~~/if-up.~~d''~~. ~~Since all scripts that reside there get called when any interface goes "up", your route setting script would be called when ''any'' interface comes up, including ''lo''~~. ~~This in turn means that a script for setting a route that belongs with a particular interface, should check on invocation which is the interface that goes up~~. ~~At this moment in time, we don't employ any such script, so no example here, but if you look at the existing scripts in ''~~/~~etc~~/~~network/if~~-~~up.d'' you'll see how other programmers have done this~~.

	==DNS resolution under Debian==		==DNS resolution under Debian==

Saruman!: Reverted edits by 212.95.54.212 (Talk); changed back to last version by Saruman!

2009-02-10T05:51:26Z

Reverted edits by 212.95.54.212 (Talk); changed back to last version by Saruman!

← Older revision		Revision as of 05:51, 10 February 2009
Line 1:		Line 1:
	~~c6aN25~~ <a ~~href="http~~://~~yidkfhyryqca~~.~~com~~/"~~>yidkfhyryqca<~~/a>, ~~[url=http~~:~~//opdpkuhnsaao~~.~~com~~/~~]opdpkuhnsaao[/url]~~, ~~[link~~=~~http~~://~~pmebsurdjoin~~.~~com~~/~~]pmebsurdjoin[~~/~~link]~~, ~~http~~://~~hmzatjmibjvg~~.~~com~~/		==Routes under Debian==

			When you need to add a networking route, there generally are two ways to do it:
			# manually adding a route at the command prompt: this means that the machine will "understand" the route for as long as it is running. However, when you reboot the machine, it will have "forgotten" the route. This is called a non-persistent route.
			# adding a route to the networking configuration files, so that it will be in place regardless of reboots or network restarts. This is called a persistent route.

			===Manipulating non-persistent routes===
			From the days of yore, the venerable ''route'' command enables us to view, add, change and delete routes. Its most known use is for printing the current routing table:
			#route -n
			Kernel IP routing table
			Destination Gateway Genmask Flags Metric Ref Use Iface
			192.168.70.0 212.214.172.50 255.255.255.0 UG 0 0 0 eth1
			192.168.67.0 * 255.255.255.0 U 0 0 0 eth0
			212.214.172.0 * 255.255.255.0 U 0 0 0 eth1
			default 212.214.172.1 0.0.0.0 UG 0 0 0 eth1
			The addition of -n makes sure the ''route'' command does not try to substitute DNS names for IP addresses it knows.
			The second most used incarnation of ''route'' lies in the addition of a route, as has happened in the previous example. The route was added to the routing table using something like this:
			#route add -net 192.168.70.0 netmask 255.255.255.0 gw 212.214.172.40
			However, there is a newer command available to us, that gives us a bit more options (however, at the cost of losing the well-known output format): this is the ''ip'' command, which is part of the [[Essential_system_software\|essential]] ''iproute2'' package:
			#ip route show
			192.168.70.0/24 via 212.214.172.50 dev eth1 src 192.168.67.10
			192.168.67.0/24 dev eth0 proto kernel scope link src 192.168.67.10
			212.214.172.0/24 dev eth1 proto kernel scope link src 212.214.172.50
			default via 212.214.172.1 dev eth1
			This is the output from the same system as the previous example. However, we see something interesting here: "ip" is capable of adding extra information to the route, like the first line shows (it's using "via"). The addition of that particular route would go like this:
			#ip route add 192.168.70.0/24 via 212.214.172.50 src 192.168.67.10

			Ofcourse, being capable of adding routes means we also need to be capable of deleting them:
			#route del -net 192.168.70.0 netmask 255.255.255.0
			#ip route del 192.168.70.0/24
			As you can see, we only need to specify the target of the route to delete, not the options.

			===Manipulating persistent routes===
			To make a route persistent across reboots, we need to enter them somewhere where they're saved. There are many possible routes available, but the two that fit Debian the most are the following:

			'''A)''' You could add the route addition command to the ''/etc/network/interfaces'' file; let the command itself be preceeded with the keyword "up" to signal the networking scripts that the command must be executed when an interface is brought "up"; the line could look like this (just as the examples from the preceeding section):
			<pre>
			# Internet interface
			auto eth1
			iface eth1 inet dhcp
			up ip route add 192.168.70.0/24 via 212.214.172.50 src 192.168.67.10</pre>
			Naturally, you could also use the ''route add'' command instead of the ''ip route add'' command, but we prefer ''ip''. Note: it matters --where-- in the ''interfaces'' file you put this line: it should be put in the same stanza as the interface it operates on. In this example, the external interface of the server is 212.214.172.50, which belongs with interface ''eth1''. Therefore, the "up" line appears in the stanza for ''eth1''.

			'''B)''' You could create a script that sets the route(s), and put it in the directory ''/etc/network/if-up.d''. Since all scripts that reside there get called when any interface goes "up", your route setting script would be called when ''any'' interface comes up, including ''lo''. This in turn means that a script for setting a route that belongs with a particular interface, should check on invocation which is the interface that goes up. At this moment in time, we don't employ any such script, so no example here, but if you look at the existing scripts in ''/etc/network/if-up.d'' you'll see how other programmers have done this.

	==DNS resolution under Debian==		==DNS resolution under Debian==

212.95.54.212: 0

2009-02-10T02:52:17Z

← Older revision		Revision as of 02:52, 10 February 2009
Line 1:		Line 1:
	=~~=Routes under Debian==~~		c6aN25 <a href="http://yidkfhyryqca.com/">yidkfhyryqca</a>, [url=http://opdpkuhnsaao.com/]opdpkuhnsaao[/url], [link=http://pmebsurdjoin.com/]pmebsurdjoin[/link], http://hmzatjmibjvg.com/

	~~When you need to add a networking route, there generally are two ways to do it~~:
	~~# manually adding a route at the command prompt: this means that the machine will "understand" the route for as long as it is running~~. ~~However, when you reboot the machine, it will have~~ "~~forgotten" the route. This is called~~ a ~~non-persistent route.~~
	~~# adding a route to the networking configuration files~~, ~~so that it will be in place regardless of reboots or network restarts. This is called a persistent route.~~

	~~===Manipulating non-persistent routes==~~=
	~~From the days of yore, the venerable ''route'' command enables us to view, add, change and delete routes. Its most known use is for printing the current routing table~~:
	~~#route -n~~
	~~Kernel IP routing table~~
	~~Destination Gateway Genmask Flags Metric Ref Use Iface~~
	~~192.168.70.0 212.214.172.50 255.255.255.0 UG 0 0 0 eth1~~
	~~192.168.67.0 * 255.255.255.0 U 0 0 0 eth0~~
	~~212.214.172.0 * 255.255.255.0 U 0 0 0 eth1~~
	~~default 212.214.172.1 0.0.0.0 UG 0 0 0 eth1~~
	~~The addition of -n makes sure the ''route'' command does not try to substitute DNS names for IP addresses it knows.~~
	~~The second most used incarnation of ''route'' lies in the addition of a route, as has happened in the previous example. The route was added to the routing table using something like this:~~
	~~#route add -net 192.168.70.0 netmask 255.255.255.0 gw 212.214.172.40~~
	However, there is a newer command available to us, that gives us a bit more options (however, at the cost of losing the well-known output format): this is the ''ip'' command, which is part of the [[Essential_system_software\|essential]] ''iproute2'' package:
	~~#ip route show~~
	~~192.168.70.0~~/~~24 via 212.214.172.50 dev eth1 src 192.168.67.10~~
	~~192.168.67.0~~/~~24 dev eth0 proto kernel scope link src 192~~.~~168.67.10~~
	~~212.214.172.0~~/~~24 dev eth1 proto kernel scope link src 212.214.172.50~~
	~~default via 212.214.172.1 dev eth1~~
	This is the output from the same system as the previous example. However, we see something interesting here: "ip" is capable of adding extra information to the route, like the first line shows (it's using "via"). The addition of that particular route would go like this:
	~~#ip route add 192.168.70.0~~/~~24 via 212.214.172.50 src 192.168.67.10~~

	~~Ofcourse~~, ~~being capable of adding routes means we also need to be capable of deleting them:~~
	~~#route del -net 192.168.70.0 netmask 255.255.255.0~~
	~~#ip route del 192.168.70.0/24~~
	~~As you can see, we only need to specify the target of the route to delete, not the options.~~

	~~===Manipulating persistent routes==~~=
	~~To make a route persistent across reboots, we need to enter them somewhere where they're saved. There are many possible routes available, but the two that fit Debian the most are the following~~:

	~~'''A)''' You could add the route addition command to the ''/etc~~/~~network~~/interfaces'' file; let the command itself be preceeded with the keyword "up" to signal the networking scripts that the command must be executed when an interface is brought "up"; the line could look like this (just as the examples from the preceeding section):
	~~<pre>~~
	~~# Internet interface~~
	~~auto eth1~~
	~~iface eth1 inet dhcp~~
	~~up ip route add 192.168.70~~.0/~~24 via 212.214.172.50 src 192.168.67.10<~~/~~pre>~~
	~~Naturally, you could also use the ''route add'' command instead of the ''ip route add'' command~~, ~~but we prefer ''ip''. Note~~: it matters --where-- in the ''interfaces'' file you put this line: it should be put in the same stanza as the interface it operates on. In this example, the external interface of the server is 212.214.172.50, which belongs with interface ''eth1''. Therefore, the "up" line appears in the stanza for ''eth1''.

	~~'''B)''' You could create a script that sets the route(s), and put it in the directory ''~~/~~etc~~/network/if-up.d''. Since all scripts that reside there get called when any interface goes "up", your route setting script would be called when ''any'' interface comes up, including ''lo''. This in turn means that a script for setting a route that belongs with a particular interface, should check on invocation which is the interface that goes up. ~~At this moment in time, we don't employ any such script, so no example here, but if you look at the existing scripts in ''~~/~~etc/network/if-up.d'' you'll see how other programmers have done this.~~

	==DNS resolution under Debian==		==DNS resolution under Debian==

Saruman!: added ipsec site2site link

2008-12-13T11:26:49Z

added ipsec site2site link

← Older revision		Revision as of 11:26, 13 December 2008
Line 77:		Line 77:
	route add -net 10.1.2.0 netmask 255.255.255.0 gw eth0.3		route add -net 10.1.2.0 netmask 255.255.255.0 gw eth0.3
	This is it; nothing to it, right?		This is it; nothing to it, right?

			=Tunneling under Debian=
			Being a Linux distribution, Debian gives you all the networking power of that platform. One of the powerful features of Linux networking is the ease with which you can create network tunnels. Many possibilities exist; in this wiki we've documented the following:
			* [[IPsec site-to-site tunnel]] with which you can connect two networks, so that machines in both networks can reach machines in the other network

Saruman!: Again undoing multiple spammer edits

2008-12-06T19:43:11Z

Again undoing multiple spammer edits

← Older revision		Revision as of 19:43, 6 December 2008
Line 1:		Line 1:
	10.~~txt~~;15;15		==Routes under Debian==

			When you need to add a networking route, there generally are two ways to do it:
			# manually adding a route at the command prompt: this means that the machine will "understand" the route for as long as it is running. However, when you reboot the machine, it will have "forgotten" the route. This is called a non-persistent route.
			# adding a route to the networking configuration files, so that it will be in place regardless of reboots or network restarts. This is called a persistent route.

			===Manipulating non-persistent routes===
			From the days of yore, the venerable ''route'' command enables us to view, add, change and delete routes. Its most known use is for printing the current routing table:
			#route -n
			Kernel IP routing table
			Destination Gateway Genmask Flags Metric Ref Use Iface
			192.168.70.0 212.214.172.50 255.255.255.0 UG 0 0 0 eth1
			192.168.67.0 * 255.255.255.0 U 0 0 0 eth0
			212.214.172.0 * 255.255.255.0 U 0 0 0 eth1
			default 212.214.172.1 0.0.0.0 UG 0 0 0 eth1
			The addition of -n makes sure the ''route'' command does not try to substitute DNS names for IP addresses it knows.
			The second most used incarnation of ''route'' lies in the addition of a route, as has happened in the previous example. The route was added to the routing table using something like this:
			#route add -net 192.168.70.0 netmask 255.255.255.0 gw 212.214.172.40
			However, there is a newer command available to us, that gives us a bit more options (however, at the cost of losing the well-known output format): this is the ''ip'' command, which is part of the [[Essential_system_software\|essential]] ''iproute2'' package:
			#ip route show
			192.168.70.0/24 via 212.214.172.50 dev eth1 src 192.168.67.10
			192.168.67.0/24 dev eth0 proto kernel scope link src 192.168.67.10
			212.214.172.0/24 dev eth1 proto kernel scope link src 212.214.172.50
			default via 212.214.172.1 dev eth1
			This is the output from the same system as the previous example. However, we see something interesting here: "ip" is capable of adding extra information to the route, like the first line shows (it's using "via"). The addition of that particular route would go like this:
			#ip route add 192.168.70.0/24 via 212.214.172.50 src 192.168.67.10

			Ofcourse, being capable of adding routes means we also need to be capable of deleting them:
			#route del -net 192.168.70.0 netmask 255.255.255.0
			#ip route del 192.168.70.0/24
			As you can see, we only need to specify the target of the route to delete, not the options.

			===Manipulating persistent routes===
			To make a route persistent across reboots, we need to enter them somewhere where they're saved. There are many possible routes available, but the two that fit Debian the most are the following:

			'''A)''' You could add the route addition command to the ''/etc/network/interfaces'' file; let the command itself be preceeded with the keyword "up" to signal the networking scripts that the command must be executed when an interface is brought "up"; the line could look like this (just as the examples from the preceeding section):
			<pre>
			# Internet interface
			auto eth1
			iface eth1 inet dhcp
			up ip route add 192.168.70.0/24 via 212.214.172.50 src 192.168.67.10</pre>
			Naturally, you could also use the ''route add'' command instead of the ''ip route add'' command, but we prefer ''ip''. Note: it matters --where-- in the ''interfaces'' file you put this line: it should be put in the same stanza as the interface it operates on. In this example, the external interface of the server is 212.214.172.50, which belongs with interface ''eth1''. Therefore, the "up" line appears in the stanza for ''eth1''.

			'''B)''' You could create a script that sets the route(s), and put it in the directory ''/etc/network/if-up.d''. Since all scripts that reside there get called when any interface goes "up", your route setting script would be called when ''any'' interface comes up, including ''lo''. This in turn means that a script for setting a route that belongs with a particular interface, should check on invocation which is the interface that goes up. At this moment in time, we don't employ any such script, so no example here, but if you look at the existing scripts in ''/etc/network/if-up.d'' you'll see how other programmers have done this.

	==DNS resolution under Debian==		==DNS resolution under Debian==

Saruman!: Reverted edits by 200.129.25.26 (Talk); changed back to last version by 221.255.206.249

2008-12-06T19:42:12Z

Reverted edits by 200.129.25.26 (Talk); changed back to last version by 221.255.206.249

← Older revision		Revision as of 19:42, 6 December 2008
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	11.~~txt;15;15~~		==DNS resolution under Debian==
			One headache you might encounter when configuring a Debian server is how to let every program know how to resolve DNS names. Before a program can connect to an external network resource (say, for example, a web server), it must have a means of converting DNS names (e.g. www.saruman.biz) into the corresponding IP addresses (e.g. 192.168.67.10). This process is called "name resolution". The need for name resolution means that every program needs to know about the available means by which to do this name resolution.

			From the good old days comes the configuration file ''resolv.conf'', normally found in ''/etc''. It contains information about the nameservers to be used by the system, be they actual servers or lookup files. However, more and more programs have the need to dynamically modify the ''resolv.conf'' configuration file. This means that frequently they step on each other, and the ''resolv.conf'' file can become out-of-sync. The ''resolvconf'' program addresses this problem. It acts as an intermediary between programs that supply nameserver information (e.g. DHCP clients) and programs that use nameserver information (e.g. resolver).

			When ''resolvconf'' is properly installed, the file ''/etc/resolv.conf'' is replaced by a symbolic link to ''/etc/resolvconf/run/resolv.conf'', and any resolver thus uses the dynamically generated resolver configuration file at ''/etc/resolvconf/run/resolv.conf''.

			The ''resolvconf'' program is only necessary when a system has multiple programs that need to dynamically modify the nameserver information. In a simple system where the nameservers do not change often or are only changed by one program, the standard ''/etc/resolv.conf'' configuration file is adequate.

	== VLANs under Debian ==		== VLANs under Debian ==

200.129.25.26: /* DNS resolution under Debian */

2008-12-06T12:05:27Z

DNS resolution under Debian

← Older revision		Revision as of 12:05, 6 December 2008
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	~~==DNS resolution under Debian==~~		11.txt;15;15
	One headache you might encounter when configuring a Debian server is how to let every program know how to resolve DNS names. Before a program can connect to an external network resource (say, for example, a web server), it must have a means of converting DNS names (e.g. www.saruman.biz) into the corresponding IP addresses (e.g. 192.168.67.10). This process is called "name resolution". The need for name resolution means that every program needs to know about the available means by which to do this name resolution.

	From the good old days comes the configuration file ''resolv.conf'', normally found in ''/etc''. It contains information about the nameservers to be used by the system, be they actual servers or lookup files. However, more and more programs have the need to dynamically modify the ''resolv.conf'' configuration file. This means that frequently they step on each other, and the ''resolv.conf'' file can become out-of-sync. The ''resolvconf'' program addresses this problem. It acts as an intermediary between programs that supply nameserver information (e.g. DHCP clients) and programs that use nameserver information (e.g. resolver).

	When ''resolvconf'' is properly installed, the file ''/etc/resolv.conf'' is replaced by a symbolic link to ''/etc/resolvconf/run/resolv.conf'', and any resolver thus uses the dynamically generated resolver configuration file at ''/etc/resolvconf/run/resolv.conf''.

	The ''resolvconf'' program is only necessary when a system has multiple programs that need to dynamically modify the nameserver information. In a simple system where the nameservers do not change often or are only changed by one program, the standard ''/etc/resolv.conf'' configuration file is adequate.

	== VLANs under Debian ==		== VLANs under Debian ==