Latest revision as of 14:42, 1 October 2006

Getting started

NEW!
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The e-book is available at no cost under a creative commons license.
Get your copy at wndw or locally and share it.

Step 1. Check where you are on the planet:

Your very first step is to find your current position on a map and then see what other wireless nodes are nearby. The best way to do this is to get a GPS and find out your coordinates and then to enter these into google earth - you can also use google earth to find your coordinates by identifying your house on the satellite image.

Step 2. Check who else is around that you can connect to

Once you have entered your google earth position - have a look at the positions of other wifi installations around you. For the Pretoria Mesh we have stored all the google earth positions in this file. You can also have a look on sites like NodeDB to see if there are other wireless installations near you. Once you have identified someone that you want to connect to, the best way to check connectivity is to use a WiFi sniffer such as netsumbler for windows or Kismet on linux loaded on a laptop with a Wifi card fitted with an external antenna. For people in Pretoria we have a kit like this that can be borrowed from our WiFi tuckshop. Find the highest point at your house such as your roof and slowly rotate the directional antenna around you to see if you can pick up any WiFi access points. You will want to find an access point that is in ad-hoc mode and is mesh enabled - the wifi sniffer will tell you if the wireless node is in ad-hoc mode but you will have to contact the owner to check what mesh protocol, if any, they are running.

Step 3. Build a mesh node

Now that you know where you are located and you have hopefully found someone you can connect to, you will need to construct your mesh hardware.

A mesh network node consists of a wireless router, antenna, routing software and settings.

Wireless Router

Your wireless router can either be a PC with a wireless card, a dedicated Wireless Router unit or SBC Single Board Computer with a wireless card. A dedicated Wireless Router is the most popular choice because it is relatively cheap, easy to configure and low power making it practicle for a device that is meant to be on most of the time. Have a look at Cost Tables to get an idea of all the possible types of mesh nodes you can build together with the cost implications

Antennae:

The first step is to select an antenna that suits your situation best. There are several types of Antennae:

1) Omnidirectional
2) Yagi-Uda
3) Grid
4) Flat-panel
5) Wave-guide

The main difference between these antennae is the Radiation Pattern. Each type is also available with different Gain specifications. Typical Wireless Routers are sold with 2 omnidirectional antennae and these can be re-used as part of your node, depending on your situation. If you have other nodes in your vicinity that are spread out in all directions but are fairly close (i.e. < 3Km), then an omni-directional antenna should suffice. If the other nodes are concentrated in one direction, for example, if you have a hill on one side of your house and theres no point in radiating the hill, then you may want to choose a more directional antenna, like a 180 degree Flat-panel. For point-to-point links, a smaller radiation angle is needed and Grid or Yagi-Uda type antennae are probably best suited.

Step 4. Install latest mesh networking firmware

The type of software that needs to be installed will typically be implmentations of mesh routing protocols like OLSR, as well as security software, like VPN clients. On dedicated wireless routers, this is typically implemented on Firmware, while on standard PC's its implemented in Software.

WRT54G Firmware update

Wireless Routers like the WRT54G are not mesh capable as is. One of the reasons for selecting the Linksys is that the Firmware is upgradeable.

Caution: Please note, that fiddling with the firmware will void your warranty!!!

The following instructions apply to networks running the OLSR routing protocl, like the Pretoria Mesh.

1. Download freifunk firmware from Freifunk site or Local

2. Set boot wait on linksys

Web method:

Navigate to web page were you can send pings and type each of these lines one line at a time

;cp${IFS}*/*/nvram${IFS}/tmp/n
;*/n${IFS}set${IFS}boot_wait=on
;*/n${IFS}commit
;*/n${IFS}show>tmp/ping.log

NVRAM method:

telnet into box and type the following

nvram set boot_wait=on nvram commit reboot

3. Upload firmware

Give yourself a fixed IP in the 192.168.1.x range e.g. 192.168.1.100

Use tftp to upload firmware

tftp 192.168.1.1
tftp> binary
tftp> rexmt 1
tftp> trace
Packet tracing on.
tftp> put openwrt-g-freifunk-1.0.2-en.bin

Wait for the power light to stop flashing Power cycle the box

Step 5. Install mesh node

HowTo Water-proof your equipment

Step 6. Setup mesh configuration

1. Check that the web interface is working. Visit the site http://192.168.1.1 on your web browser - you should see the main freifunk web interface appear

2. Set up the wireless interface

WLAN protocol: Static
Ip Address: 192.168.2.5
Netmask: 255.255.255.0
WLAN Mode: Ad Hoc (Peer to Peer)
ESSID: mesh
Channel: 6
TX Power: 100

3. Set up the LAN interface

LAN protocol: Static
LAN IP: 192.168.4.1
LAN Netmask: 255.255.255.0
Disable NAT: yes
Disable Firewall: yes

4. Set up the WAN interface

WAN Protocol: DHCP
Host name: Lawrence

5. Set up OLSR

HNA4: 192.168.4.1 255.255.255.0

6. Restart the Linksys

You should now be given an IP address in the 192.168.3.x range You should be able to connect to another mesh access point and even get a default gateway to an internet point, if one exists

Step 7. Start surfing

Hopefully you`re now hooked up to the internet and you can start surfing the web or hooking up to other PCś on the mesh

Step 8. Troubleshoot

Start with Layer 1:

Is everything switched on?
Is the LAN plugged in?
Is the Antenna connected?
Is it facing the right direction?
Is it polarised correctly?

Check software settings:

Is the correct antenna selected?
Is the routing daemon running?

WRT54G HowTos

HowTo choose which antenna port to use on the WRT54G for an external antenna

Where to connect the external antenna

WRT54g v1, v1.1, v2 
look at the backside and connect the external antenna to the right antenna connector

WRT54g v2.2 v3 3.1 v4 and the WRT54GL v1.0
look at the backside and connect the external antenna to the left antenna connector

HowTo create an ipk package

TOOLS

Get the script rightfully called ipkg-build at, among other places, ftp://ftp.handhelds.org/packages/ipkg-utils, or http://www.mizi.com/download/mz20/ipkg-build.

CREATING THE PACKAGE STRUCTURE

Say you wanna create a package called MyPackage; you further wanna package the project called MyProject. Then do the following:

  1. Create a directory called MyPackage.
  2. Inside directory MyPackage, create a directory called CONTROL.
  3. Copy your project (MyProject) to the MyPackage directory.
  4. Inside directory CONTORL creating a file called control.

NOTE:

When the package is installed on the target, the MyPAckage directory will be created with respect to root. So if you wanted your files to be installed in /usr/bin on the target system, then our project would in this case be “/usr/bin”. That is you create inside directory MyPackage a directory called /usr/bin.

FORMAT AND CONTENTS OF /CONTROL/control

Package: MyPackage

Priority: optional // default

Version: 1.0 //package version

Architecture: mipsel

Maintainer: I_maintain@you.com

Source: ftp:ftp:122.122.122.122 //See Note below

Section: misc //See Note below

Description: This is an attempt to create ipkg.

NOTE:

The fields Section and Source seem rather useless to me in this example and I initially left them out; however the ipkg-build script complained requiring them, so I just put them in as a workaround without knowing/”caring” of their need. There are other fields not included here which you might need for your purposes, check the web for more.

Further the comments are mine for this documentation purposes only and the script MIGHT NOT permit comments.

RUNNING THE ipkg-build SCRIPT

Now simply run (of course being outside of the directory MyPackage):

“./ipkg-build –c –o root –g root MyPackage” // as root or non-root, or

“./ipkg-build –c MyPackage” //as root

IF all’s well, a package on the current directory will be created.

NOTE:

Without the “-c” option, I could not get the package installed successfully, you can try with or without and see for yourself.

HowTo run Kismet on a WRT54G

Install either the kismet or kismet_drone package.
Edit /etc/kismet_drone.conf and change the source from wrt54g,eth1,wrt45g to wrt54g,prism0,wrt54g.
Run kismet from your host, pc and off u go!

HowTo check your Linksys WRT54G version

Finally some good info about finding the version number from outside markings and using NVRAM settings - info from www.openwrt.org

Linksys WRT54G

  1. Hardware versions
              1. Identification by S/N
        1. WRT54G v1.0
        2. WRT54G v1.1
        3. WRT54G v2.0
        4. WRT54G v2.2
        5. WRT54G v3.0 & WRT54G v3.1
        6. WRT54G v4.00
  2. Table summary
  3. Hardware hacking

1. Hardware versions

There are currently seven versions of the WRT54G (v1.0, v1.1, v2.0, v2.2, v3.0, v3.1, v4.00). With the exception of v4.00 devices (it is currently marked as untested for White Russian RC1), the WRT54G units are supported by OpenWrt 1.0 (White Russian) and later. boot_wait is off by default on these routers, so you should turn it on. The version number is found on the label on the bottom of the front part of the case below the Linksys logo. 1.0.1. Identification by S/N

Useful for identifying shrinkwrapped units. The S/N can be found on the box, below the UPC barcode.

(!) Please contribute to this list. (!)

Model	S/N	CVS	EXP
WRT54G v1.1	CDF20xxxxxxx CDF30xxxxxxx	(./)	(./)
WRT54G v2	CDF50xxxxxxx	(./)	(./)
WRT54G v2.2	CDF70xxxxxxx	{X}	(./)
WRT54G v3	CDF80xxxxxxx	{X}	(./)
WRT54G v3.1 (AU?)	CDF90xxxxxxx	{X}	(./)

1.1. WRT54G v1.0

The WRT54G v1.0 is based on the Broadcom 4710 board. It has a 125MHz CPU, 4Mb flash and 16Mb SDRAM. The wireless NIC is a mini-PCI card. The switch is an ADM6996. 1.2. WRT54G v1.1

The WRT54G v1.1 is based on the Broadcom 4710 board. It has a 125MHz CPU, 4Mb flash and 16Mb SDRAM. The wireless NIC is soldered to the board. The switch is an ADM6996.

Hardware informations (nvram) :

boardtype=bcm94710dev

1.3. WRT54G v2.0

The WRT54G v2.0 is based on the Broadcom 4712 board. It has a 200MHz CPU, 4Mb flash and 16Mb SDRAM. The wireless NIC is integrated to the board. The switch is an ADM6996.

Hardware informations (nvram) :

boardtype=0x0101 boardflags=0x0188

1.4. WRT54G v2.2

The WRT54G v2.2 is based on the Broadcom 4712 board. It has a 200MHz CPU, 4Mb flash and 16Mb DDR-SDRAM. The wireless NIC is integrated to the board. The switch is a BCM5325.

Hardware informations (nvram) :

boardtype=0x0708 boardflags=0x0118

1.5. WRT54G v3.0 & WRT54G v3.1

This unit is just like the V2.2 Except it has an extra reboot button on the left front panel behind a Cisco logo. 1.6. WRT54G v4.00

Please add information for this revision.

Hardware informations (nvram) :

boardrev=0x10 boardtype=0x0708 boardflags2=0 boardflags=0x0118 boardnum=42

/!\ To take the front cover off of this unit you must first remove the small screws under the rubber covers of the front feet! 2. Table summary

how to get info :

board info: nvram show | grep board | sort
cpu model: cat /proc/cpuinfo | grep cpu

Model	boardrev	boardtype	boardflags	boardflags2	boardnum	wl0_corerev	cpu model
WRT54G v1.1		bcm94710dev			42	5	BCM4710 V0.0
WRT54G v2.0		0x0101	0x0188				BCM3302 V0.7
WRT54G v2.2		0x0708	0x0118			7
WRT54G v3.0	0x10	0x0708	0x0118	0	42	7	BCM3302 V0.7
WRT54G v3.1 (AU?)	0x10	0x0708	0x0118	0	42	7	BCM3302 V0.7
WRT54G v4.0	0x10	0x0708	0x0118	0	42	7	BCM3302 V0.7
WRT54GS v1.0	0x10	0x0101	0x0388	0	42	7	BCM3302 V0.7
WRT54GS v1.1	0x10	0x0708	0x0318	0	42
Buffalo WBR-54G	0x10	bcm94710ap	0x0188	2	42
Toshiba WRC1000		bcm94710r4			100
Buffalo WBR2-G54S	0x10	0x0101	0x0188	0	00
Asus WL-500G Deluxe	0x10	bcm95365r			45	5	BCM3302 V0.7

other variables (nvram) of interest : boot_ver, pmon_ver, firmware_version, os_version

please complete this table. Look at this thread : [WWW] http://openwrt.org/forum/viewtopic.php?pid=8127#p8127 May be this table should move up to OpenWrtDocs/Hardware. 3. Hardware hacking

There are revision XH units of the WRT54G v2.0. These units have 32Mb of memory, but they are locked to 16Mb. You can unlock the remaining memory with changing some of the variables. Afterburner (aka. Speedbooster) mode can be enabled with some variables, too.

/!\ However, there are no guaranties, that these will work, and changing the memory configuration on a non-XH unit will give You a brick. Check the forums for more info. If you have a look at the WRT54G v2.2 board, you can find on the left corner, near the power LED, an empty place for a 4 pins button. On the board it is printed as SW2. This is the second reset button you can find on WRT54G v3.0, except that it has not been soldered.

HowTo Stabilise a ver 2.2 WRT54G running OpenWRT based firmware

After a lot of tweaking OLSR running on Linksys has had no "ping down" messages for about 5 days now. Some of the tips to getting OLSR on OpenWRT stable.

1. Lock all the nodes to 802.11B don't let it auto sense 2. If there are any v2.2 hardware devices, change the clock speed to 216MHz with the following commands1

nvram set clkfreq=216
nvram commit
reboot

3. Lock the RX and TX antenna to the one you connected your external antenna too, don't use AUTO. TAKE NOTE!!! On Version 2.0 hardware Antenna A is on the left looking from the front of the linksys and and on Version 2.,2 hardware Antenna A is on the right looking from the fron of the linksys. This caught me out a few times.

HowTo configure netmasks on OLSR/Freifunk

I had this problem with the OLSR web interface on the Freifunk openwrt implementation. If entered the following for the HNA4 field

HNA4: 10.3.13.1 255.255.255.0

Which should advertise the whole 10.3.13.x net it would advertise the 10.0.0.0 net. I discovered that it needs the subnet mask in this format instead

HNA4: 10.3.13.1/24

A few other things I learnt

1. NVRAM variable ff_hna4 stores the HNA4 setting 2. /etc/olsr.conf is ignored by freifunk 3. /rom/etc/olsrd.conf stores a permanent copy of the olsrd setup 4. /var/etc/olsrd.conf is a symbolic link to /tmp/etc/olsrd.conf ... this file is copied from /rom/etc/olsrd.conf into RAM (ramfs filesystem) and is the one called by olsrd.

ps -A will reveal that olsrd is called as follows

olsrd -f /var/etc/olsrd.conf -d 0

HowTo Brick and De-Brick a WRT54G

Theres nothing like learning the hard way! As a result of my usual "If it ain't broke, it hasn't been fixed enough" approach to life, I fiddled with the Linksys until it innevitably went into a coma/ vegetative state. How did I manage this you ask? Simple, I started by doing a firmware upgrade using the wrong sveasoft image, which resulted in a moderately upset linksys which refused to talk to me on the web interface. With the help of our trusted Android (Andrew), I managed to do a reset-hold/ ping / tftp recovery and then flashed the poor bugger with OpenWRT, which according to OpenWRT is still not supported by them for the version 2.2 Linksys, which I subsequently found out I was using! So alas, all that remained was a perfectly dead Linksys, not responding to anything. It was time to go in, screwdrivers a blazing. I shorted out pins 15 and 16 and started up the Linksys, this created a crc error which was detected on boot, this then started up an emergency TFTP server which allowed me to ping and finally tftp the original Linksys firmware back onto it!

More details on the recovery processes can be found here: OpenWrtDocs/Troubleshooting - OpenWrt

Whew!

How to set up Linksys as a RIP2 router with client mode

1. Load Alchemy pre-release 5.2.3 onto the linksys

2. Set the Linksys Wireless interface to Client mode and set SSID to "pta-mesh"

Using the web interface select Wireless - Basic Settings Wireless Mode : Client SSID: pta-mesh Select Save Settings - continue

3. Choose your IP addresses for the Wireless interface and the LAN interface

I chose the following WAN interface: 10.50.1.13 LAN interface: 10.3.11.1

Using the Web interface select Setup - Basic Setup Internet Connection Type: Static IP Internet IP Address: 10.50.1.13 Subnet Mask: 255.255.255.0 Router Name: Something you like eg. david_home Local IP Address: 10.3.11.1 Subnet Mask: 255.255.255.0

Select Save Settings - continue

4. Add router configuration files to the target directory

Enter the router directory ($LINKSYS/src/router)

cd /mipsel-uclibc/target
mkdir /usr/local
mkdir /usr/local/etc

Download my RIP configuration files for linksys ripd.conf zebra.conf

Copy these files to $LINKSYS/src/router/mipsel-uclibc/target/usr/local/etc

Download my image making script which will build files in the code.bin image makeimage.sh

Copy this script to $LINKSYS/src/router Run the script ./makeimage.sh

You should now have a code.bin with the router config files in /usr/local/etc Upload this new firmware to the linksys

5. Add commands to rc_startup to startup RIP, Flush iptables (so that RIP messages can arrive on RIP port) and remove NAT

zebra -d -f /usr/local/etc/zebra.conf ripd -d -f /usr/local/etc/ripd.conf iptables -F iptables -F -t nat

8. You should now have a rip enabled linksys client - Try ping the network connected to the wireless interface from a machine connected to the LAN

Things to improve in this recipe 1. Don't flush all iptables - just enable the port for RIP routing 2. Find location in Makefile where the code.bin image is made - don't need my custom script

HowTo route between WLAN and LAN on a WRT54G with Sveasoft

Make sure you have installed Sveasoft Alchemy 5.2.4

Go to Administration - Diagnostics and enter the following into the command line

brctl delif br0 eth1
ifconfig eth1 down
ifconfig eth1 up
if addr add 192.168.2.1/24 dev eth1

Click on "save startup" Reboot linksys

This will create a new subnet for the wireless side of the router on the 192.168.2.0 network The LAN side of the router will remain on the 192.168.1.0 network

HowTo Cross compile for the WRT54G

Got a c++ program compiled for linksys

The C++ environment is configured!

1. Download the linksys firmware source
2. Copy the brcm/ directory from /tools to /opt
3. add /opt/brcm/hndtools-mipsel-linux/bin to your path
4. add /opt/brcm/hndtools-mipsel-uclibc/bin to your path

Use mipsel-linux-g++ compiler to compile any c++ code
Don't use the mipsel-uclibc-g++ compiler - this was my mistake!
Now we can try compile mobile mesh for linksys

HowTo create/be part of a VPN

Getting IPSEC installed on your Linksys using Freifunk

Reflashing the firmware

Follow the link to http://edna/ftp/pub/mesh/linksys/os/freifunk/firmware/openwrt-gl11-freifunk-1.2.5-de.bin Download this file and then upload to your router

Login to the router via ssh

Type the following commands

ipkg update
ipkg install libgmp
ipkg install freifunk-openwrt-compat
ipkg install openswan

Now goto step 3 below to see how to configure IPSEC

Getting IPSEC installed on your Linksys using Openwrt (RC5)

1. Upgrade Linksys to OpenWRT (RC5)

There are two options: if one wants to upgrade to RC5 with all the required packages already built in, follow the instructions in (a). If RC5 is already installed and one needs to update the packages, follow the instructions in (b).

(a) Reflashing the firmware

Tip: It migth be useful to copy the olsr.conf file from the Linksys to the host PC BEFORE upgrading.

Follow the link ftp://ftp2.za.freebsd.org/pub/mesh/whiterussian_rc5/firmware/ to select the firmware (files with "-squashfs.bin") that matches the model of your LinkSys router. Note that a "new Linksys" implies a new Linksys used for the first time which has not been upgraded yet, i.e. the firmware that comes with Cisco - Linksys is installed.

Save the file on your client machine (machine connected to your LinkSys).
Logon via the web browser onto your LinkSys; e.g http://w.x.y.z ; where w.x.y.z is the ethernet address of your LinkSys (usually this is 192.168.1.1)
The system will/might ask (warn) you to set the password. Password must be set to change anything to the router. So, set password! Note after this step telnet will be disabled, and instead will need to use ssh instead "ssh root@w.x.y.z"
Upgrade the firmware:
- Openwrt: Select (under CATEGORIES) "System" then select "Firmware upgrade"
- New linksys: Select Administration; then select "Firmware Upgrade"
Choose to "Erase JFFS2 partition" under "Options" (Freifunk or new Linksys does not have this option)
Click on "Browse" to select the firmware you've downloaded from ftp://ftp2.za.freebsd.org
Click on "Upgrade"

PLEASE DO NOT INTERRUPT THE UPGRADE PROCESS IN ANYWAY. Watch the DMZ light go on and then off after which time the router should be ready. Wait for about 3-5 minutes to be safe for the system to upgrade itself.

When upgrading a new linksys, it will let display a new page on the web interface: "upgrade is successful". Pressing the Continue button will show: " The requested URL was not found on this server." This is because one has upgraded to OpenWRT which has a different URL. Point to the URL 192.168.1.1 again to see OpenWRT's web interface.

(b) Installing required packages

If you have Openwrt(RC5) already installed but do not have IPSec then download from ftp://ftp2.za.freebsd.org/pub/mesh/whiterussian_rc5/packages/ the following packages and install them using ipkg in the order listed below:

kmod-openswan_2.4.30brcm+2.4.4-2_mipsel.ipk

libgmp_4.1.4-1_mipsel.ipk

openswan_2.4.4-1_mipsel.ipk

ip_2.6.11-050330-1_mipsel.ipk

Below is what happens on my box:

root@Lawrence:~# ipkg install kmod-openswan_2.4.30brcm\+2.4.4-2_mipsel.ipk

Installing kmod-openswan (2.4.30brcm+2.4.4-2) to root...

Configuring kmod-openswan

Successfully terminated.

root@Lawrence:~# ipkg install libgmp_4.1.4-1_mipsel.ipk

Installing libgmp (4.1.4-1) to root...

Configuring libgmp

Successfully terminated.

root@Lawrence:~# ipkg install openswan_2.4.4-1_mipsel.ipk

Installing openswan (2.4.4-1) to root...

Configuring openswan

Successfully terminated.

root@Lawrence:~# ipkg install ip_2.6.11-050330-1_mipsel.ipk

Installing ip (2.6.11-050330-1) to root...

Configuring ip

Successfully terminated.

NOTE: It's important to note that although the 3 packages above are all the core packages for IPsec; IPsec might still not run depending on your current installation. For example, the script /etc/lib/ipsec/_updown, hence Ipsec, will fail to run if the command "ip" is not installed.

2. Configure network settings

Configuration is done using the web interface. Unfortunately everything is not configurable via the web, and a second step of the configuration is required via an ssh session.

Step 1: Configuration via web interface:

Click on Categories: Systen: Settings
enter new password (if it is the first time, it will ask for it)
login root, new passwd
Enter host name
Save settings
Click on Categories: Network: LAN
Enter Lan's IP address with the required netmask
Save Settings
Click on "WAN"
Select none
Save settings
click on "Wireless"
Select ESSID
Select Channel
select Mode: Ad-Hoc
Save settings
Apply changes
The linksys will reboot...

Step 2: Configuration via ssh

ssh to root@192.168.1.1
Remove Bridge

nvram set lan_ifname=vlan0
nvram set lan_ifnames=vlan0

Setup Wireless interface

nvram set wifi_ifname=eth1
nvram set wifi_proto=static
nvram set wifi_ipaddr=10.60.30.2    ##get ip address from your admin
nvram set wifi_netmask=255.255.255.0
nvram commit
nvram reboot

Setup olsr
- copy olsrd.conf to Linksys's tmp dir
- rm olsrd.conf in etc dir (breaking symbolic link to ROM)
- copy olsr.conf ot the /etc dir
- restart olsr or reboot
rm /etc/init.d/S45firewall

3. Configure IPSEC

STOPPING IPSEC

After the either of the above steps, ipsec will be run automatically. You need to stop IPSec before continuing with the follwoing steps. Do the following:

ssh root@w.x.y.z

root@LinkSys:/#ipsec setup stop

CONFIGURATION

STEP 1:

Do the following:

cd /etc
rm ipsec.conf #by default this file is created as a link to one found in /rom directory (which is read-only)
vi ipsec.conf #Edit by any means you can
Enter the following lines and save the file

NOTE: You can ignore to type in the comments ( Text starting with/after #), however do as the comments say

version 2

config setup
 interfaces="ipsec0=eth1"    # replace "eth1" with the name of your wireless interface
 klipsdebug=none 
 plutodebug=none 
 uniqueids=yes
conn %default
 keyingtries=0
 authby=secret #rsasig
conn crypt
 left=10.50.1.80             # replace "10.50.1.80" with the ip address of your wireless interface
 leftid=10.50.1.80           # replace "10.50.1.80" with the ip address of your wireless interface
 leftsubnet=10.1.13.1/24     # replace "10.1.13.1" with the ethernet ip address of your router
 right=10.50.1.3             # replace "10.50.1.3" with the ip address of the IPSec server. Ask Net admin
 rightid=10.50.1.3           # replace "10.50.1.3" with the ip address of the IPSec server. Ask Net admin
 rightsubnet=146.64.8.8/16   # Do not change this line to access CSIR network
 auto=start                  # This line ensures IPSec is automatically started when the router starts up.
 type=tunnel

STEP 2:

Edit the /etc/ipsec.secrets to contain a line similar to the one below in between the stars (excluding the stars)

10.50.1.3 10.50.1.80: PSK "presharedkey"

NOTE: The Ip addresses above should be as in ipsec.conf above. Ask the Net admin for the string pre-shared key (presharedkey) which must be enclosed in double quotes as shown above.

RUNNING IPSEC

root@LinkSys:/#ipsec setup restart

TEST IPSEC At this point, you should be able to reach/ping any machine on the rightsubnet (146.64.X.Y as in the ipsec.conf above) as specified in your ipsec.conf file.

Establishing IPsec tunnel/connection between FreeBSD and Linux (openswan IPsec Cisco WRT54G Router)

Below is a simple setup demonstrating steps to establish an IPsec connection/tunnel between two machines one running Ipsec/racoon (on FreeBSD) and the other running openswan Ipsec (on WRT54G running Linux) using pre-shared key: This IPsec setup example shows how to control the Private LAN_A (146.64.0.0) network access.

.........(INTERNET)

.........|

..| FreeBSD | ......10.50.1.3..............................10.50.1.80| Openswan IPsec|

.| Router_A |<========> (“NETWORK”)<=======>| Router_B |

.| 146.64.17.1 |................................................................| 10.1.13.1 |

............ ||.........................................................................||

...Private LAN_A....................................................PPrivate LAN_B

...........|.......................................................................................|........... ....Client_A (146.64.17.12) ..................................Client_B (10.1.13.130)

NOTE: Before running racoon/ipsec and openswan ipsec, ensure that all nodes can successfully reach (ping) each other.

INSTALLING OPENSWAN ON WRT54G

To install, add the following to /etc/ipkg.conf:

src openswan ftp://ftp.openswan.org/openswan/binaries/openwrt/buildroot-20040509/ipkg/

and then run:

ipkg update

ipkg install gmp mawk openswan-module openswan

NOTE: Since /etc/ipkg.conf would normally be a link to the file in /rom directory; You can simple delete the link, and then copy the file over.

CONFIGURATION (Router_A IPsec)

There are three (3) configuration files on Router_A that needs to be edited: ipsec.conf (found in /etc on FreeBSD), psk.conf.(found in /usr/local/etc/racoon/ on FreeBSD) and racoon.conf.(found in /usr/local/etc/racoon/ on FreeBSD).

Add the following two lines in ipsec.conf: (This file defines the ends points of the tunnel to be established. There’d be two lines for each LAN_B client )

spdadd 146.64.0.0/16 10.1.13.0/24 any -P out ipsec esp/tunnel/10.50.1.3-10.50.1.80/require;
spdadd 10.1.13.0/24 146.64.0.0/16 any -P in ipsec esp/tunnel/10.50.1.80-10.50.1.3/require;

Roughly; the first line says “traffic coming from 146.64.0.0 network destined for 10.1.13.0 network must be transported via an IPsec tunnel with local endpoint 10.50.1.3 and far endpoint 10.50.1.80”.

The second line says “traffic coming from 10.1.13.0 network destined for 146.64.0.0 network must/would use an IPsec tunnel with a far endpoint 10.50.1.80 and local endpoint 10.50.1.3”.

Add the following line to psk.conf (This file defines the pre-shared key to be used between Router_A and Router_B).

10.50.1.80 presharedkey

NOTE: Comments must be on a different line to the pre-shared key entry, otherwise the comments are interpreted as part of the pre-shared key.

Add the following lines to racoon.conf

path pre_shared_key "/usr/local/etc/racoon/psk.txt" ;
remote anonymous
{
# exchange_mode aggressive,main ;
exchange_mode main ;
lifetime time 24 hour ;
proposal {
 encryption_algorithm 3des ;
 hash_algorithm sha1;
 authentication_method pre_shared_key ;
 dh_group 2 ;
 }
}
sainfo anonymous
{
lifetime time 12 hour ;
encryption_algorithm 3des, blowfish, des, rijndael ;
authentication_algorithm hmac_sha1, hmac_md5 ;
compression_algorithm deflate ;
}

IMPORTANT: The IPsec version (2.3.1) used in this example did not seem to support “aggressive” exchange_mode hence “main” is specified. However, it is possible to include more than mode by separating them with comma; i.e.

exchange_mode aggressive, main ;

Both ways (specifying one or more modes) works! Further other lines with more than one values separated by comma may contain only one value as described for exchange_mode above.

CONFIGURATION (Openswan IPsec, Router_B)

There are two (2) files on Router_B that needs editing: ipsec.conf (found in /etc on Linux) and ipsec.secrets (found in /etc on Linux).

Add the following line in ipsec.secrets: (This file defines the ends points of the tunnel to be established and also the pre-shared key to be used)

10.50.1.3 10.50.1.80: PSK “presharedkey”

NOTE: 1. Place the string after PSK in quotes if it does not start with 0x (as in a hexadecimal number), otherwise openswan will complain.

2. The string after PSK must be the same as that specified in psk.conf on Router_A.

Add the following lines in ipsec.conf: (This file defines among other things, the network to be protected, authentication methods, type of connection, etc.)

config setup
 interfaces="ipsec0=eth1"
 klipsdebug=none
 plutodebug=none
 uniqueids=yes
conn %default
 keyingtries=0
 authby=secret #rsasig
conn crypt
 left=10.50.1.80
 leftid=10.50.1.80
 leftsubnet=10.1.13.1/24
 right=10.50.1.3
 rightid=10.50.1.3
 rightsubnet=146.64.8.8/16
 auto=start
 type=tunnel

NOTE: The name of our connection is called “crypt”. Under “config setup”, the line interfaces=”ipsec0=eth1” must refer to a real interface (ifconfig will show available interfaces) and also must be the interface through which the data to be protected will travel, in case of more than one NIC. The line “auto=start” says, the connection “crypt” must be brought up when openswan ipsec starts up; to bring up the connection manually either comment out the line or specify “auto=ignore”. The explanation given for ipsec.conf on Router_A is pretty much the same as for Router_B.

STARTING UP IPsec and Racoon (FreeBSD).

At this point all machines are able to reach (ping) each other successfully. Next ensure ipsec and racoon are not running. On my machine I do:

verdi2istc#/etc/rc.d/ipsec stop

Clearing ipsec manual keys/policies.

to stop ipsec if it was already running; and do

verdi2istc# setkey -P -D

No SPD entries.

To ensure there are no IPsec SA/SP database entries; and next do

verdi2istc#killall racoon

to stop racoon.

Next issue

verdi2istc# /etc/rc.d/ipsec restart

to start ipsec, and to verify ipsec started successfully then do

verdi2istd# setkey -P -D

10.1.13.0/24[any] 146.64.0.0/16[any] any

in ipsec

esp/tunnel/10.50.1.80-10.50.1.3/require

created: Aug 30 09:27:39 2005 lastused: Aug 30 09:27:39 2005

lifetime: 0(s) validtime: 0(s)

spid=16531 seq=1 pid=583

refcnt=1

146.64.0.0/16[any] 10.1.13.0/24[any] any

out ipsec

esp/tunnel/10.50.1.3-10.50.1.80/require

created: Aug 30 09:27:39 2005 lastused: Aug 30 09:27:39 2005

lifetime: 0(s) validtime: 0(s)

spid=16530 seq=0 pid=583

refcnt=1

From Router_A, type either racoon (to run in the backgroung) or racoon –F

verdi2istd#racoon

or to fun in foreground type

verdi2istd#racoon -F -d

Foreground mode.

2005-08-30 09:51:59: INFO: main.c:172:main(): @(#)package version freebsd-20040818a

2005-08-30 09:51:59: INFO: main.c:174:main(): @(#)internal version 20001216 sakane@kame.net

2005-08-30 09:51:59: INFO: main.c:175:main(): @(#)This product linked OpenSSL 0.9.7d 17 Mar 2004 (http://www.openssl.org/)

2005-08-30 09:51:59: DEBUG: pfkey.c:434:pfkey_init(): call pfkey_send_register for AH

2005-08-30 09:51:59: DEBUG: pfkey.c:434:pfkey_init(): call pfkey_send_register for ESP

2005-08-30 09:51:59: DEBUG: pfkey.c:434:pfkey_init(): call pfkey_send_register for IPCOMP

2005-08-30 09:51:59: DEBUG: cftoken.l:578:yycf_set_buffer(): reading config file /usr/local/etc/racoon/racoon.conf

2005-08-30 09:51:59: DEBUG: pfkey.c:2379:pk_checkalg(): compression algorithm can not be checked because sadb message doesn't support it.

2005-08-30 09:51:59: DEBUG: grabmyaddr.c:206:grab_myaddrs(): my interface: 10.50.1.3 (ath0)

2005-08-30 09:51:59: DEBUG: grabmyaddr.c:206:grab_myaddrs(): my interface: fe80::202:6fff:fe21:2e71%ath0 (ath0)

2005-08-30 09:51:59: DEBUG: grabmyaddr.c:206:grab_myaddrs(): my interface: 146.64.8.1 (sis0)

2005-08-30 09:51:59: DEBUG: grabmyaddr.c:206:grab_myaddrs(): my interface: fe80::200:24ff:fec2:b684%sis0 (sis0)

2005-08-30 09:51:59: DEBUG: grabmyaddr.c:206:grab_myaddrs(): my interface: 127.0.0.1 (lo0)

2005-08-30 09:51:59: DEBUG: grabmyaddr.c:206:grab_myaddrs(): my interface: ::1 (lo0)

2005-08-30 09:51:59: DEBUG: grabmyaddr.c:206:grab_myaddrs(): my interface: fe80::1%lo0 (lo0)

2005-08-30 09:51:59: DEBUG: grabmyaddr.c:474:autoconf_myaddrsport(): configuring default isakmp port.

2005-08-30 09:52:00: DEBUG: grabmyaddr.c:496:autoconf_myaddrsport(): 7 addrs are configured successfully

2005-08-30 09:52:00: INFO: isakmp.c:1368:isakmp_open(): fe80::1%lo0[500] used as isakmp port (fd=5)

2005-08-30 09:52:00: INFO: isakmp.c:1368:isakmp_open(): ::1[500] used as isakmp port (fd=6)

2005-08-30 09:52:00: INFO: isakmp.c:1368:isakmp_open(): 127.0.0.1[500] used as isakmp port (fd=7)

2005-08-30 09:52:00: INFO: isakmp.c:1368:isakmp_open(): fe80::200:24ff:fec2:b684%sis0[500] used as isakmp port (fd=8)

2005-08-30 09:52:00: INFO: isakmp.c:1368:isakmp_open(): 146.64.8.1[500] used as isakmp port (fd=9)

2005-08-30 09:52:00: INFO: isakmp.c:1368:isakmp_open(): fe80::202:6fff:fe21:2e71%ath0[500] used as isakmp port (fd=10)

2005-08-30 09:52:00: INFO: isakmp.c:1368:isakmp_open(): 10.50.1.3[500] used as isakmp port (fd=11)

2005-08-30 09:52:00: DEBUG: pfkey.c:197:pfkey_handler(): get pfkey X_SPDDUMP message

2005-08-30 09:52:00: DEBUG: policy.c:184:cmpspidxstrict(): sub:0xbfbfea30: 146.64.0.0/16[0] 10.1.13.0/24[0] proto=any dir=out

2005-08-30 09:52:00: DEBUG: policy.c:185:cmpspidxstrict(): db :0x809dc08: 10.1.13.0/24[0] 146.64.0.0/16[0] proto=any dir=in

The –d option is for debug, to see more output add extra –d.

IMPORTANT: At this point if all went well Client_A should not be reachable (try ping) from Router_B and Client_B; meaning private LAN_A is now protected. However, Router_A and Router_B should be able reach/see each other. Do not continue until this is accomplished.

STARTING UP OPENSWAN IPSEC

Now, on Router_B do:

root@Lawrence:/# ipsec setup restart

ipsec_setup: Stopping Openswan IPsec...

ipsec_setup: Starting Openswan IPsec 2.3.1...

verify that the IPsec tunnel has been established correctly by issuing:

root@Lawrence:/# ipsec whack --status

000 interface ipsec0/eth1 10.50.1.80

000 %myid = (none)

000 debug none

000

000 algorithm ESP encrypt: id=3, name=ESP_3DES, ivlen=64, keysizemin=168, keysizemax=168

000 algorithm ESP encrypt: id=12, name=ESP_AES, ivlen=128, keysizemin=128, keysizemax=256

000 algorithm ESP auth attr: id=1, name=AUTH_ALGORITHM_HMAC_MD5, keysizemin=128, keysizemax=128

000 algorithm ESP auth attr: id=2, name=AUTH_ALGORITHM_HMAC_SHA1, keysizemin=160, keysizemax=160

000

000 algorithm IKE encrypt: id=7, name=OAKLEY_AES_CBC, blocksize=16, keydeflen=128

000 algorithm IKE encrypt: id=5, name=OAKLEY_3DES_CBC, blocksize=8, keydeflen=192

000 algorithm IKE hash: id=2, name=OAKLEY_SHA1, hashsize=20

000 algorithm IKE hash: id=1, name=OAKLEY_MD5, hashsize=16

000 algorithm IKE dh group: id=2, name=OAKLEY_GROUP_MODP1024, bits=1024

000 algorithm IKE dh group: id=5, name=OAKLEY_GROUP_MODP1536, bits=1536

000 algorithm IKE dh group: id=14, name=OAKLEY_GROUP_MODP2048, bits=2048

000 algorithm IKE dh group: id=15, name=OAKLEY_GROUP_MODP3072, bits=3072

000 algorithm IKE dh group: id=16, name=OAKLEY_GROUP_MODP4096, bits=4096

000 algorithm IKE dh group: id=17, name=OAKLEY_GROUP_MODP6144, bits=6144

000 algorithm IKE dh group: id=18, name=OAKLEY_GROUP_MODP8192, bits=8192

000

000 stats db_ops.c: {curr_cnt, total_cnt, maxsz} :context={0,0,0} trans={0,0,0} attrs={0,0,0}

000

000 "crypt": 10.1.13.0/24===10.50.1.80...10.50.1.3===146.64.0.0/16; erouted; eroute owner: #2

000 "crypt": srcip=unset; dstip=unset

000 "crypt": ike_life: 3600s; ipsec_life: 28800s; rekey_margin: 540s; rekey_fuzz: 100%; keyingtries: 0

000 "crypt": policy: PSK+ENCRYPT+TUNNEL+PFS+UP; prio: 24,16; interface: eth1;

000 "crypt": newest ISAKMP SA: #1; newest IPsec SA: #2;

000 "crypt": IKE algorithm newest: 3DES_CBC_192-SHA1-MODP1024

000

000 #2: "crypt":500 STATE_QUICK_I2 (sent QI2, IPsec SA established); EVENT_SA_REPLACE in 27961s; newest IPSEC; eroute owner

000 #2: "crypt" esp.2ec9213@10.50.1.3 esp.aa7dc439@10.50.1.80 tun.1002@10.50.1.3 tun.1001@10.50.1.80

000 #1: "crypt":500 STATE_MAIN_I4 (ISAKMP SA established); EVENT_SA_REPLACE in 2625s; newest ISAKMP; nodpd

000

root@Lawrence:/#

At this point Client_A should be reachable by Client_B. On each/either Router do a tcpdump; and any packets with ESP indicates that the setup tunnel is currently handling data from the clients.

NOTE: ESP packets will only appear if there are packets from either client to the other client.

DEBUGGING (Openswan IPsec)

Earlier I showed how to stop a connection from being started up automatically by openswan. IPsec. So now with ipsec running but our connection “crypt” NOT up, we will debug the starting up of the connection (crypt). To debug the key exchange with racoon, first create a script with following content:

ipsec pluto --debug-all

ipsec whack \

--name crypt \

--tunnel \

--host 10.50.1.80 \

--nexthop 10.50.1.3 \

--client 10.1.13.1/24 \

--updown 'ipsec _updown' --id 10.50.1.80 \

--to \

--host 10.50.1.3 \

--client 146.64.8.1/16 \

--updown 'ipsec _updown' --id 10.50.1.3 \

--psk \

--esp 3des-md5,3des-sha1 \

--ike 3des-md5,3des-sha1 \

--encrypt

ipsec whack --listen

ipsec whack --route --name crypt

ipsec whack --initiate --name crypt

Running this script will show the various key exchange messages. The messages are pretty much clear to see what it’s happening.

HowTo stop DHCP client over-writing resolv.conf

Finally I found out how to do it

Edit the /etc/dhcp3/dhclient.conf file Find the line that says request

Comment out the line that requests for domain-name, domain-name-servers and host-name

request subnet-mask, broadcast-address, time-offset, routers,
# domain-name, domain-name-servers, host-name,
netbios-name-servers, netbios-scope;

HowTo setup DHCP with OLSR

There have been so many misleading postings on this - I will finally set the record straight.

You will need to reserve a block of IP's for non OLSR wireless clients that want to connect onto the mesh network such as a laptop. Here is an example setup:

Wireless router 1: Wireless IP: 10.51.1.13 LAN IP: 10.3.13.1 Subnet for Wireless DHCP clients: 10.51.1.64/28 (This would mean that 16 machines could potentially connect to this wireless router. The IP leases will be in the range from 10.51.1.64 to 10.51.1.79)

Wireless router 2: Wireless IP: 10.51.1.14 LAN IP: 10.3.14.1 Subnet for Wireless DHCP clients : 10.51.1.80/28 (IP leases will be in the range from 10.51.1.80 to 10.51.1.93)

To set this up On Friefunk firmware Wireless Router 1: OLSR: OLSR DHCP: 10.51.1.64/28

Wireless Router 2: OLSR: OLSR DHCP: 10.51.1.80/28

Most people gave strange values for OLSR DHCP in their postings the most common one was: OLSR DHCP: 10.51.1.80/28, 255.255.255.240

The subnet mask after the comma (255.255.255.240) is an alternative to the slash format /28. Why does everyone have this reduntant subnet mask on their postings???

Linux HowTos

HowTo setup your own network profiles on a laptop

I have always wanted to write some good scripts that configure my laptop for home and work wireless/ethernet automatically in ubuntu and so I set about building up a set of scripts that I can call.

I have four scenarios: 1. use laptop at home with wireless access point 2. use laptop at home with ethernet 3. use laptop at work with wireless access point 4. use laptop at work with ethernet

I created two files in /etc/network: interfaces.work and interfaces.home with all the ethernet and wireless settings for home and work in this file

/etc/network/interfaces.home

This file describes the network interfaces available on your system
and how to activate them. For more information, see interfaces(5).

The loopback network interface

auto lo iface lo inet loopback

The primary network interface

iface eth0 inet static address 10.3.13.102 netmask 255.255.255.0 gateway 10.3.13.1

The wireless network interface

iface eth1 inet dhcp wireless-essid pta-mesh wireless-mode Ad-Hoc wireless-channel 1 wireless-key off

/etc/network/interfaces.work

This file describes the network interfaces available on your system
and how to activate them. For more information, see interfaces(5).

The loopback network interface

auto lo iface lo inet loopback

The primary network interface

iface eth0 inet dhcp

The wireless network interface

iface eth1 inet dhcp wireless-essid icomtek wireless_mode Managed wireless-key off

I also created two files with my dns and domain settings for home and work in /etc/ called resolv.home and resolv.work

resolv.home search icomtek.csir.co.za elarduspark.org.za cids.org.za nameserver 146.64.28.1 10.3.13.1

resolv.work search icomtek.csir.co.za cids.org.za nameserver 146.64.28.1

Here are my scripts that configure my interfaces based on the above files

1. Setup for wireless networking at home /usr/local/bin/homenet-wireless

!/bin/bash

echo Setting up network for home wireless network sudo cp /etc/network/interfaces.home /etc/network/interfaces

eth0_status=`ifconfig | grep eth0` eth1_status=`ifconfig | grep eth1`

if [ -n "$eth0_status" ]; then sudo ifdown eth0 fi

if [ -n "$eth1_status" ]; then sudo ifdown eth1 fi

sudo ifup eth1

sudo cp /etc/resolv.home /etc/resolv.conf

2. Setup for ethernet networking at home /usr/local/bin/homenet-fixed

!/bin/bash

echo Setting up network for home ethernet sudo cp /etc/network/interfaces.home /etc/network/interfaces sudo cp /etc/resolv.home /etc/resolv.conf

eth0_status=`ifconfig | grep eth0` eth1_status=`ifconfig | grep eth1`

if [ -n "$eth0_status" ]; then sudo ifdown eth0 fi

if [ -n "$eth1_status" ]; then sudo ifdown eth1 fi

sudo ifup eth0

3. Setup for wireless at work /usr/local/bin/worknet-wireless

!/bin/bash

echo Setting up network for work wireless network sudo cp /etc/network/interfaces.work /etc/network/interfaces sudo cp /etc/resolv.work /etc/resolv.conf

eth0_status=`ifconfig | grep eth0` eth1_status=`ifconfig | grep eth1`

if [ -n "$eth0_status" ]; then sudo ifdown eth0 fi

if [ -n "$eth1_status" ]; then sudo ifdown eth1 fi

sudo ifup eth1

4. Setup for ethernet at work /usr/local/bin/worknet-fixed

!/bin/bash

echo Setting up network for work ethernet sudo cp /etc/network/interfaces.work /etc/network/interfaces sudo cp /etc/resolv.work /etc/resolv.conf

eth0_status=`ifconfig | grep eth0` eth1_status=`ifconfig | grep eth1`

if [ -n "$eth0_status" ]; then sudo ifdown eth0 fi

if [ -n "$eth1_status" ]; then sudo ifdown eth1 fi

sudo ifup eth0

HowTo Setup a Linux machine to become an access point

1. Make sure you install dhcpd off the Mandrake disks

2. Put the Wireless card into access point mode with the following example script /etc/sysconfig/network-scripts/ifcfg-wifi0

DEVICE=wifi0
BOOTPROTO=static
IPADDR=192.168.0.1
ONBOOT=yes
NETMASK=255.255.255.0
NETWORK=192.168.0.0
BROADCAST=192.168.0.255
DHCP_TIMEOUT=5
WIRELESS_MODE=Master
WIRELESS_ESSID=mesh
WIRELESS_CHANNEL=10

3. run ifup wifi0

4. copy /etc/dhcpd.conf.sample (this file only exisits the first time you install dhcpd) to dhcpd.conf ... Change the IP address allocations in this file to suite your needs

5. start dhcpd with /etc/rc.d/init.d/dhcpd

6. Check the /var/lib/dhcpd/dhcpd.leases to check which IP addresses are being assigned

HowTo Set up the SENOA card in linux

1. Download the hostap driver from ftp://edna.icomtek.csir.co.za/pub/drivers ... This driver ensures that the SENOA card can run in Access point mode as well as Ad-Hoc and Infrastructure

2. Unzip using gunzip < hostap-driver-0.2.4.tar.gz | tar xvf -

3. Change Makefile to include KERNEL_PATH ... KERNEL_PATH=/usr/src/linux

4. Run 'make'

5. run 'make install'

6. Restart card manager using /etc/rc.d/init.d/pcmcia restart

If you are using the PCI to PCMCIA bridge card with the RLSC475 chipset follow these steps

1. Edit the file /etc/sysconfig/pcmcia to include these lines

PCMCIA=yes
PCIC=RLSC475

2. Run /etc/rc.d/init.d/pcmcia restart

Linux network configurations tips

1. Setting IP address and modes of interface

The file /etc/sysconfig/network-scripts/ifcfg-eth0 contains all the settingsfor interface eth0 including

IP allocation type (static or dynamic)
IP Address
Subnet mask
Broadcast address
Wireless mode
wireless channel

type

# man ifcfg

to see all the options for this config file

Use

# ifup eth0

to bring eth0 network interface up using the script ifcfg-eth0

#ifdown eth0

to pull the eth0 interface down

2. The DNS nameserver

The file /etc/resolve.conf contains the nameserver (dns) to use for the network

3. The gateway and other network routes

To see the current network routes type

# route

This will show you all the routes which the network is currently using

To add a new route for interface eth0 type

# route add -net 10.0.0.0 netmask 255.255.255.0 dev eth0

This adds a route to the network 10.0.0.0 using device eth0

# route add default gw 10.0.0.8

Adds a default route which will be used if no other route matches.

There should be an existing route, in this case, to 10.0.0.8 through some interface.

HowTo use the freespace loss equation

From: Radio theory and link planning for Wireless LAN (WLAN)

Everyone should know the free space loss equation in their head

Loss [ dB] = 32.44 + 20(Log(distance[km]) + Log(freq[MHz]))

Useful cable losses

RG58 = 1 dB/m RG213 = -.6 dB/m RG174 = 2 dB/m (often used in pigtails) LMR-400 = 0.22 dB/m

Typical WiFi sensitivity for orinoco cards

11Mbps = -82dBm 5.5Mbps = -87dBm 2Mbps = -92dBm 1Mbps = -94dBm

Typical allowed signal to noise ratios for orinoco cards

11Mbps = 16dB 5.5Mbps = 11dB 2Mbps = 7dB 1Mbps = 4dB

Typical Noise level at 2.4GHz = -100dBm. Compute S/N level eg. at 11Mbps = -84dBm but sensitivity is -82dBm so sensitivity is the limiting factor.

Just worked out that with our 2 8dBi omnis, 2dB loss in the RF cable each side of the link and the 200mW SENOA cards it is possible to acheive a theoretical distance of 5km with a 3dB margin (margin probably a bit tight), 4km will give you a 5dB margin - probably more realistic.