Round Robin Dns

Udgivet den juli 21, 2002 af mike

Round Robins Dns is a simple form of load ballancing, you have 2 or more servers which provides the same servive e.g. irc or www. You want half of the users to use server A and the other half to use server B.

But users are stupid they cant figure out which server to connect to so therefore you can create a round robin dns entry.

In its simple mind its all about two A-record in you dns, if you make:

myservice.org IN A 192.168.0.1
myservice.org IB A 192.168.0.2

The first request for myservice.org will get 192.168.0.1 the next 192.168.0.2 and so on. I know of no limit on this.

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How to connect a Linux system to an IPv6 gateway

Udgivet den juli 21, 2002 af mike

First you have to make sure that the kernel is ipv6 kombatible, do an ifconfig and look for something like this inet6 addr: fe80::202:44ff:fe27:23bd/10 Scope:Link if you cant find it, try type modprobe ipv6 and look again, if it dosnt help you have to make a new kernel.

When you have assured that IPv6 support is in play you can go on by adding an IPv6 adress to your ethernet interface:

This makes the interface eth0 respond to the address “3ffe:1234:1234::1234” and sets the scope(netmask) to /48

ifconfig eth0 add 3ffe:1234:1234::1234/48

Now you can test this by pinging local network nodes , for an instance the router which will most likeley be “3ffe:1234:1234::1” or “3ffe:1234:1234::”

ping6 3ffe:1234:1234::1

Now when we have assured that we can ping our local route we can go on add the default gateway, this is done with this command:

route -A inet6 add 2000::/3 gw 3ffe:1234:1234::1

This tells the IPv6 stack to send all trafik which does not belong to 3ffe:1234:1234::0/48 to the router 3ffe:1234:1234::1

The ping6 and traceroute6 can be obtained from:
http://ftp.debian.org/debian/pool/main/i/iputils/iputils_20020124.orig.tar.gz

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IPIP Tunneling in linux

Udgivet den juli 21, 2002 af mike 
With ipip tunneling you can connect to LAN through internet 
like this:

____________                    ____________
|           |                   |           |
|   Lan1    |___________________|   Lan2    |
| 10.1.x.x  |      Internet     | 10.2.x.x  |
|___________|                   |___________|
 Global IP:                      Global IP:
 80.80.80.80                     90.90.90.90

If ipip-tunneling wasnt compiled into the kernel but is compile 
as a module you have to modprobe it first, use:
modprobe ipip

Then we make the tunnel it self, "tundev" is the name of the 
device that will be created to host the tunnel. 80.80.80.80 is 
the tunnel endpoints IP.
iptunnel add tundev mode ipip remote 80.80.80.80

Then the tundev interface needs an ip, this will typical be the 
same as the lan adresss of the server.
ifconfig tundev 10.2.1.1

And finaly we add routing, this line tells the TCP/IP stack that 
network 10.1.0.0/16 (10.1.x.x) can be reached through gateway 
10.2.1.1 via the interface tundev
route add -net 10.1.0.0/16 gw 10.2.1.1 dev tundev


Finally two examples that shows how to link the two above lans. 
Both must be ran on the server which has the global IP bounded 
to an interface.

 this is for Lan1
modprobe ipip
iptunnel add tundev mode ipip remote 90.90.90.90
ifconfig tundev 10.1.1.1
route add -net 10.2.0.0/16 gw 10.1.1.1 dev tundev

 this is for Lan2
modprobe ipip
iptunnel add tundev mode ipip remote 80.80.80.80
ifconfig tundev 10.2.1.1
route add -net 10.1.0.0/16 gw 10.2.1.1 dev tundev
Udgivet i Knowledge Base, Linux, Networking, Old Base, Uncategorized | 1 kommentar

The foundation of Unifix Knowledge Base

Udgivet den juni 21, 2002 af mike

Dette system har sin oprindelse i 2 sider af en sag, den ene var at vi tit stod i den problemstilling at vi havde lavet et eller andet og 2 måneder efter ikke kunne huske hvordan vi havde gjort det. Den anden var at vi tit flere gentagne gange måtte fortælle andre hvordan vi havde gjort en given ting, hvilket vi til sidst blev trætte af, derfor oprettede vi knowledge basen, i daglig tage base.

Meningen er at man åbner base i en browser mens man arbejder med sit problem og løbende tager noter, gemmer url og hvad man ellers laver. Det skal være skrevet så du selv om 20 år kan læse det og gentage det præcis om dengang, det er hoved filosofien med systemet. Når så du er færdig og dit projekt kører klikker du på ‘public’ og så kan folk se dine noter.

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