Openwrt

Openwrt knowledge

NVRAM

NVRAM is the EEPROM of the wrt54g. The Settings stored in the NVRAM is used by openwrt to configure the network interfaces and other settings like timezone and so on.

INfo's about NVRAM settings

OLSR

OLSR means Optimized Link State Routing protocol.

OLSR is a routing protocol for mobile ad-hoc networks. The protocol is pro-active, table driven and utilizes a technique called multipoint relaying for message flooding. You can configure multiple openwrt routers to talk to each other to find the best route from point A to point B.

WDS

WDS (Wireless Distribution System) can be used to mae a special tunnel between two openwrt's. It is also supported by many other Accesspoints. I didn't bring it to work so i had been looking for another solution. MESH networks soltuions can do that. OLSR is one implementation for that. AODV is another one.

Installing the software

Installing the openwrt firmware

I use this script to takeover the wrt54g. Get your firmware and copy it to the same directory as the takeover script.

Whether to use jffs2 or sqashfs is a philosophical question.

Plug in your wrt54g to you linux box. Configure your box in side 192.168.1.0/24 (not 192.168.1.1!)

Code: Installing openwrt on the Linksys wrt54g

wget http://downloads.openwrt.org/whiterussian/rc2/bin/openwrt-wrt54g-jffs2.bin wget https://aachen.uni-dsl.de/download/wrt/Snapshots/rev121/buildroot-rev121/takeover chmod +x takeover cp openwrt-wrt54g-jffs2.bin openwrt-g-code.bin ./takeover

Wait about 5 minutes. If openwrt is booting the DMZ LED should lightning.

Installing openvpn

Code: Installing openvpn

ipkg update ipkg install openvpn

Code: /etc/init.d/S60openvpn

#!/bin/sh # load Bridging-Module #modprobe bridge openvpn --mktun --dev tap0 # configure bridge brctl addbr br1 brctl stp br1 off brctl setfd br1 0 brctl addif br1 vlan0 brctl addif br1 tap0 ifconfig vlan0 0.0.0.0 promisc up ifconfig tap0 0.0.0.0 promisc up ifconfig br1 192.168.25.172 netmask 0xffffff00 broadcast 192.168.25.255 echo 1 > /proc/sys/net/ipv4/conf/br1/forwarding openvpn --config /etc/openvpn/server.conf &

Code: /etc/openvpn/server.conf

port 1194 proto tcp-server dev tap0 ca /etc/openvpn/keys/ca.crt cert /etc/openvpn/keys/server.crt key /etc/openvpn/keys/server.key # This file should be kept secret dh /etc/openvpn/keys/dh1024.pem #this will assign connecting clients address between the range of 10 and 50 #openwrt IP is 192.168.25.172 server-bridge 192.168.25.172 255.255.255.0 192.168.25.10 192.168.25.50 #this will allow for people to get the same IP address after a reconnect ifconfig-pool-persist /etc/openvpn/ipp.txt push "dhcp-option DNS 192.168.25.179" keepalive 10 120 max-clients 10 persist-key persist-tun

Code: /etc/openvpn/server.conf

#the ip address of the openwrt box remote 10.7.0.1 float proto tcp-client dev tap persist-tun redirect-gateway #to set /etc/resolv.conf if necessary up /etc/openvpn/wlan/client.up down /etc/openvpn/wlan/client.down pull tls-client cert /etc/openvpn/wlan/keys/client1.crt ca /etc/openvpn/wlan/keys/ca.crt key /etc/openvpn/wlan/keys/client1.key

You now need to make the keys. You can use the easy-rsa script from the openvpn package. Get it from the homepage.

Installing olsrd

Code: Installing olsrd

ipkg install olsrd

Code: /etc/olsrd.conf

[...] Hna4 { #The Network which the dhcp server is responsable for 10.7.0.0 255.255.255.0 # Setting only on the box which has direct Internet Access 0.0.0.0 0.0.0.0 } [...] Interface "eth1" { # Hello interval in seconds(float) HelloInterval 10.0 # HELLO validity time HelloValidityTime 200.0 # TC interval in seconds(float) TcInterval 25.0 # TC validity time TcValidityTime 500.0 # MID interval in seconds(float) MidInterval 25.0 # MID validity time MidValidityTime 500.0 # HNA interval in seconds(float) HnaInterval 25.0 # HNA validity time HnaValidityTime 500.0 }

Append a '&' to 'olsrd $OPTIONS' in /etc/init.d/olsrd so it look like:

       olsrd $OPTIONS &

Code: Starting olsrd

mv /etc/init.d/olsrd /etc/init.d/S60olsrd /etc/init.d/S60olsrd start