OpenWRT Tor transparent proxy+bridge
This document gives some instructions on how to setup, on OpenWRT platform, a wireless network, whose clients gets tunneled transparently through Tor. Optionally, a public Tor bridge can be configured.
Status of Tor on OpenWRT
Tor is generally well maintained on OpenWRT and it relies on community support. For detailed OpenWRT install and configuation, please see OpenWRT_setup_notes
Minimum hardware requirements are :
- 64 Mio RAM (32Mio is too low, tor crashes because of that)
- 32 Mio flash (you may want to use a usb stick if you don't have that much flash on your router)
- A fast processor (ex: Atheros 700MHz cpu is enough to route 10Mbps over Tor, no more)
That tutorial investigates the (Buffalo WZR-HP-G300NH (US) / Buffalo WZR-HP-G300NH (UK) / Buffalo WZR-HP-G300NH (DE) / OpenWRT wiki) hardware. See the open tickets in the Status section below for current state. This runs OpenWRT.
Note that the cpu should prevent you from running more than ~6Mbps over tor (to be tested).
TP-LINK TL-WR1043ND is also a good candidate with a more powerful CPU than the Buffalo, and a lot cheaper (~60€). Note that only v2.x and v3.x of that hardware match hardware requirements for tor. Due to small flash you must use an usb key for storage.
Re-flashing the stock operating system to something reproducible
At the moment, we're using a stock OpenWRT (backfire 10.03.1-rc4) build as our router base OS. In the future, we will build our own images and that build information will be added to this page when it is relevant. The default operating system for the target hardware platform is either a modified version of DD-WRT (buffarlo) or stock TP-LINK firmware. For various reasons, we want to reflash the OS to a stock OpenWRT.
Flashing Buffalo with OpenWRT
You have mainly two « easy » options, both described in openwrt wiki to install openwrt on your router :
- using ssh on the stock firmware (modified DD-WRT)
- Alternatively, you can use the alternate method (see next section)
- Still you can use TFTP method (a bit harder)
Alternate buffalo flash method
If SSH cannot be enabled for any reason on the factory DD-WRT, FLASH the new OpenWRT image by first loading a vanilla DD-WRT image.
1. Obtain shell access on the router using a vanilla DD-WRT
Download DD-WRT from here by typing wzr-hp-g300nh in the search box and downloading the "Special File for initial flashing." The filename should be something like buffalo_to_ddwrt_webflash-MULTI.bin. Now, flash DD-WRT on to the router from the stock web interface, and wait for it to boot. Note that this takes a little while, at least a minute. The DIAG LED will be lit, then it will blink, and when it's not lit the router is ready for action.
Go to the DD-WRT web interface by browsing to http://192.168.1.1/ (standard user: root, pw empty) and enable Telnet management this way: Administration (Tab) -> Management (Tab) -> Remote Access (Group) -> Telnet. Telnet into the router using the same credentials as for the web interface.
Congratulations, you have a shell. Now on to OpenWRT.
2. Once you have a remote shell on the router
Once you have a remote shell and are able to issue commands as root, this is the way to reflash your router:
cd /tmp wget http://downloads.openwrt.org/backfire/10.03.1-rc4/ar71xx/openwrt-ar71xx-wzr-hp-g300nh-jffs2-sysupgrade.bin mtd -r write openwrt-ar71xx-wzr-hp-g300nh-jffs2-sysupgrade.bin linux
Flashing TPLINK TL-WR1043ND with OpenWRT
The procedure is detailed in OpenWRT wiki, (works well with OpenWrt BarrierBreaker 14.07).
Get ready to set up OpenWRT
After flashing your router, it automatically reboots into a mint OpenWRT that listens on 192.168.1.1 with a password-less telnet root shell. Connect via ethernet (you might have to manually set your interface address to something like 192.168.1.2) to one of the Buffalo's four LAN ports,
log in via telnet:
and set a new root password:
root@OpenWrt:~# passwd Changing password for root New password: Retype password: Password for root changed by root
After setting a password, telnet shuts down and an SSH server starts on the router. So log out, log back via SSH as root, and connect the router's WAN port to your home DHCP router for the rest of the setup process.
Update and install packages
Update the package list:
Before OpenWRT 11 you had to install the proper iptables packages. Now they are included, so if you are on OpenWRT 11 you can leave out this step:
opkg install iptables-mod-nat iptables-mod-nat-extra
opkg install tor
These packages should be installed but if they're not - install wireless driver and AP support packages:
opkg update opkg install kmod-ath9k opkg install wpad-mini
Now reconfigure the wireless network:
cat << 'EOF' > /etc/config/wireless # # XXX TODO: We want to ensure the wireless AP has a static MAC # This will ensure that no GeoIP database of MAC addresses can locate a client # leaking MAC data. # config wifi-device radio0 option type mac80211 option channel 11 option phy phy0 option hwmode 11ng option htmode HT20 list ht_capab SHORT-GI-40 list ht_capab DSSS_CCK-40 # REMOVE THIS LINE TO ENABLE WIFI: # option disabled 1 config wifi-iface option device radio0 option network transtor option mode ap option ssid 'Transparent Tor' option encryption none option macaddr 00:88:88:88:00:2A # see http://outflux.net/geoloc/?mac=00-88-88-88-00-2A+ for the location info associated with this mac addr EOF
Configure Tor as a bridge:
cat << 'EOF' > /etc/tor/torrc # This is a configuration for a Tor bridge on the WAN interface # and it also runs with a transport to allow for transparent proxying # on a specific wireless interface. # User tor RunAsDaemon 1 PidFile /var/run/tor.pid DataDirectory /var/lib/tor # This is for our transparent network VirtualAddrNetwork 10.192.0.0/10 AutomapHostsOnResolve 1 TransPort 9040 TransListenAddress 192.168.2.1 DNSPort 9053 DNSListenAddress 192.168.2.1 # GeoIP for stats # DO NOT UNCOMMENT THIS LINE UNTIL GEOIP SUPPORT IS CONFIRMED # GeoIPFile /etc/tor/geoip EOF
Add the following only if you want/can host a public tor bridge (optional).
cat << 'EOF' >> /etc/tor/torrc # This is our bridge for the world to use Nickname OpenWRTTorBridge SocksPort 0 ORPort 443 BridgeRelay 1 Exitpolicy reject *:* # This is where we rate limit the bridge to something reasonable RelayBandwidthRate 100 KBytes RelayBandwidthBurst 200 KBytes EOF
Add new network interface for Tor wireless network:
cat << 'EOF' >> /etc/config/network config interface transtor option ifname "wlan0" option proto static option ipaddr 192.168.2.1 option netmask 255.255.255.0 EOF
Update the DHCP config to ensure that DHCP is provided for wireless clients on the transparent Tor wifi network:
cat << 'EOF' >> /etc/config/dhcp config 'dhcp' 'transtor' option 'interface' 'transtor' option 'start' '23' option 'limit' '250' option 'leasetime' '12h' EOF
Update the master firewall config:
cat << 'EOF' >> /etc/config/firewall #Allow Tor Bridge incoming for censored users config rule option src wan option proto tcp option dest_port 443 option target ACCEPT config zone option name transtor option input REJECT option output ACCEPT option forward REJECT option syn_flood 1 option conntrack 1 #this setting is mandatory # Allow Transparent clients the ability to DHCP an address # XXX TODO: Audit this to ensure it doesn't leak UDP port 67 to the net! config rule option src transtor option proto udp option dest_port 67 option target ACCEPT # Tor transparent-proxy-port (set in /etc/tor/torrc) config rule option src transtor option proto tcp option dest_port 9040 option target ACCEPT # Tor DNS-proxy-port (set in /etc/tor/torrc) config rule option src transtor option proto udp option dest_port 9053 option target ACCEPT EOF
Update the user supplied iptables rules:
cat << 'EOF' >> /etc/firewall.user # Redirection rules for Transparent Tor iptables -t nat -A PREROUTING -i wlan0 -p udp --dport 53 -j REDIRECT --to-ports 9053 iptables -t nat -A PREROUTING -i wlan0 -p tcp --syn -j REDIRECT --to-ports 9040 EOF
Re-detect the wireless:
Reload the network:
Restart the firewall:
Now your router should be a Tor bridge with port 443 open to the world on the WAN port. It will also advertise a wireless network with the SSID "Transparent Tor" and any client joining that network will be given an RFC1918 address with all of their traffic being routed through Tor. Any traffic that is unsupported (non-DNS UDP, ICMP, etc) will be rejected by the router. If this router is behind a NAT, we will not currently open the required ports as the current OpenWRT project does not build with tor-fw-helper.
Disk Space Problems
If you run into problems where tor crashes due to the lack of disk space (flash being so small) add the following into /etc/tor/torrc: