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In order to communicate via TCP/IP to your FreeRunner, a basic understanding of the networking expectations is required. Each end of the USB connection forms a LAN (local area network) segment, with the FreeRunner's USB networking device at one end (default 192.168.0.202) and your laptop or desktop at the other end (192.168.0.200 in this guide).
Normally, your desktop machine will know how to reach the Internet, having had its gateway (the IP address of the machine or device which knows how to send packets to machines beyond your subnet) configured via DHCP or statically (probably via a router). For the FreeRunner to reach the Internet, your desktop will have to be configured to route and masquerade (NAT) packets from it.
Normally, none of this is an issue, but problems can arise when the subnet between the FreeRunner and your desktop overlap with the desktop to the router (which forms a second LAN), since your desktop might not know how to route traffic properly.
In other words: if your existing router and desktop have addresses 192.168.0.(something) changing them to eg 192.168.1.(something) might save you a lot of troubleshooting later. The guides to set up USB networking for your FreeRunner assume that your router/desktop IP range differs from the USB network IP range.
Try this first. If it works, then you can add permanent configuration or use more sophisticated setups below:
(as root on your desktop):
iptables -A POSTROUTING -t nat -j MASQUERADE -s 192.168.0.0/24 sysctl -w net.ipv4.ip_forward=1 ifconfig usb0 192.168.0.200
If your Internet connection is also in the range 192.168.0.x then instead you might want to use:
ifconfig usb0 192.168.0.200 netmask 255.255.255.248
Then (ideally, not as root):
ssh root@192.168.0.202
The default password is blank.
Your Linux desktop/laptop needs to have suitable support, in particular, you will need to have enabled full masquerading in the kernel and USB networking options enabled. For default kernels in many Linux distributions, this will already be the case. If not, you will need to enable:
Both USB networking options are available in the Device Drivers -> USB support -> USB Network Adapters or Device Drivers -> Network Device Support -> USB Network Adapters -> Multipurpose USB Networking Framework. For more info see the usbnet driver homepage.
It can be complex to set all the correct options for masquerading in the kernel if they are not turned on. This could be detailed further.
On some systems, you may have firewall rules which prevent this working - such as added by the iptables service on Fedora. You may care to stop these, and/or review any rules or policies you think might cause issues.
The most relevant table is the nat table, which controls translation of addresses:
iptables -L -t nat -v -n
Unless you have a special setup, you'll want to see only the MASQUERADE rule that you apply below, and ACCEPT as the default policy. Also look at the filter table:
iptables -L -t filter -v -n
If this contains anything in the FORWARD chain, then this may prevent passing packets. It can be flushed with:
iptables -t filter -F FORWARD
In addition to routing issues, to be practical, DNS will need to work. In some cases, you might already be running a DNS server on your desktop such as dnsmasq or bind9, which is the default assumption the FreeRunner makes. In other cases, you'll need to configure DNS to that of your router, or a DNS server further out on the internet such as that provided by your ISP.
DNS is configured in /etc/resolv.conf on your FreeRunner. It should contain:
nameserver 192.168.0.200
Which means that by default it expects your desktop to have a DNS server. On some Linux and Windows systems this is true, especially those configured as servers, but in general it is not. You can install packages such as bind9 or dnsmasq. See the section below on More on DNS for other solutions.
Test if it works:
ping www.google.com
If so, then this is sufficient for most internet access. But manual changes to resolv.conf are usually lost later if for example one uses DHCP, especially for WiFi, and so may not be convenient to configure manually.
Log in with a blank password (press enter). Now, make sure you can ping back to your desktop:
ping 192.168.0.200
This tests the basic network connection.
(Note that some systems like Vista, don't respond to ICMP ping by default)
Or your router, for example (your IP will probably be different):
ping 192.168.1.99
Or to a Google IP:
ping 74.125.19.147
This demonstrates that masquerading is working - your desktop is sending/receiving packets to the wider internet.
Based on Hotplugging usbnet by Marcin 'Hrw' Juszkiewicz.
Edit /etc/network/interfaces and add:
allow-hotplug usb0 iface usb0 inet static address 192.168.0.200 netmask 255.255.255.192 post-up iptables -A POSTROUTING -t nat -j MASQUERADE -s 192.168.0.192/26 post-up echo 1 > /proc/sys/net/ipv4/ip_forward post-up iptables -P FORWARD ACCEPT pre-down iptables -D POSTROUTING -t nat -j MASQUERADE -s 192.168.0.192/26
This is more sophisticated than the manual setup. The allow-hotplug stanza ties into Linux hotplug system so that when the device appears and vanishes, as happens when the FreeRunner's is connected via USB, this is run.
In addition, the desktop-side netmask is limited to a much smaller range, so that overlapping subnets are less of a problem - Linux will use more specific routes first when deciding where to send packets.
An other possible configuration that adds DNS forward and removes the iptable changes after the unplugg.
in /etc/network/interfaces add
# freerunner allow-hotplug usb0 iface usb0 inet static address 192.168.0.200 netmask 255.255.255.192 post-up /etc/network/freerunner start pre-down /etc/network/freerunner stop
create file /etc/network/freerunner
#!/bin/sh # # configures the freerunner for internet # # DEVICE=usb0 IPADDR=192.168.0.200 REMOTE_IPADDR=192.168.0.202 NETMASK=255.255.255.0 # get first ip for dns DNSIP=$(cat /etc/resolv.conf | grep nameserver | awk '{ print $2 }' | head -n 1 ) case "$1" in start) iptables -A POSTROUTING -t nat -j MASQUERADE -s $REMOTE_IPADDR iptables -A PREROUTING -t nat -p tcp -s $REMOTE_IPADDR -d $IPADDR --dport domain -j DNAT --to-destination $DNSIP iptables -A PREROUTING -t nat -p udp -s $REMOTE_IPADDR -d $IPADDR --dport domain -j DNAT --to-destination $DNSIP if [ "$(cat /proc/sys/net/ipv4/ip_forward)" = "0" ]; then echo "temoprarely allow ip_forward for openmoko" > /var/run/openmoko.ip_forward echo 1 > /proc/sys/net/ipv4/ip_forward fi ;; stop) iptables -D POSTROUTING -t nat -j MASQUERADE -s $REMOTE_IPADDR iptables -D PREROUTING -t nat -p tcp -s $REMOTE_IPADDR -d $IPADDR --dport domain -j DNAT --to-destination $DNSIP iptables -D PREROUTING -t nat -p udp -s $REMOTE_IPADDR -d $IPADDR --dport domain -j DNAT --to-destination $DNSIP if [ -f /var/run/openmoko.ip_forward ]; then rm /var/run/openmoko.ip_forward echo 0 > /proc/sys/net/ipv4/ip_forward fi ;; esac
Make /etc/network/freerunner executable with
chmod +x /etc/network/freerunner
Ubuntu Feisty, Gutsy and Hardy reportedly have a bug where ifdown is not run when the interface is unplugged, meaning this only works once after the system is booted. This is mentioned at https://bugs.launchpad.net/ubuntu/+source/ifupdown/+bug/130437
One can patch /etc/udev/rules.d/85-ifupdown.rules, editing the two lines at the end of the file:
SUBSYSTEM=="net", DRIVERS=="?*", GOTO="net_start" GOTO="net_end" LABEL="net_start" # Bring devices up and down only if they're marked auto. # Use start-stop-daemon so we don't wait on dhcp ACTION=="add", RUN+="/sbin/start-stop-daemon --start --background --pidfile /var/run/network/bogus --startas /sbin/ifup -- --allow auto $env{INTERFACE}" LABEL="net_end" ACTION=="remove", RUN+="/sbin/start-stop-daemon --start --background --pidfile /var/run/network/bogus --startas /sbin/ifdown -- --allow auto $env{INTERFACE}"
The bug is that the LABEL="net_end" is at the wrong position
This appears to be fixed in Ubuntu 8.04 Mattt 11:38, 30 July 2008 (UTC)
Tested with Mandriva 2008.1. The idea here is that we will carve out a small (8 hosts) subnet from the main subnet. So our netmask will be 255.255.255.252
This first file configures the network system for the usb0 interface. Any time you plug in the FreeRunner the interface will be configured.
/etc/sysconfig/network-scripts/ifcfg-usb0:
DEVICE=usb0 BOOTPROTO=static IPADDR=192.168.0.200 NETMASK=255.255.255.252 ONBOOT=yes METRIC=10 MII_NOT_SUPPORTED=no USERCTL=yes
This next file configures the static routes that we need to communicate to the subnet. Since it has "usb0" in the name, the system will automatically apply these static routes any time that the usb0 interface is configured. (i.e. when you connect the FreeRunner)
/etc/sysconfig/network-scripts/usb0-routes:
ADDRESS0=192.168.0.200 NETMASK0=255.255.255.252
Now we need to restart the network system to pick up the changes.
service network restart
/etc/sysconfig/network/ifcfg-usb0:
# USB configuration for PDAs (openmoko) IPADDR=192.168.0.200 NETMASK=255.255.255.0 STARTMODE=onboot
For more information on getting USB networking up using YaST, see USB Networking with openSUSE.
/etc/sysconfig/network-scripts/ifcfg-usb0:
# USB configuration for PDAs (openmoko) # from http://www.handhelds.org/moin/moin.cgi/UsbNet DEVICE=usb0 BOOTPROTO=none IPADDR=192.168.0.200 NETMASK=255.255.255.0 ONBOOT=yes
This setup is probably over-complex:
/etc/sysconfig/network-scripts/ifcfg-usb0:
DEVICE=usb0 IPADDR=192.168.0.200 NETMASK=255.255.255.0
/etc/sysconfig/network-scripts/ifup-usb:
#!/bin/bash . /etc/init.d/functions cd /etc/sysconfig/network-scripts . ./network-functions [ -f ../network ] && . ../network CONFIG=${1} need_config ${CONFIG} source_config NETBITS=`ipcalc -p ${IPADDR} ${NETMASK} | awk -F'=' '{print $2;}'` /sbin/ip addr flush dev ${DEVICE} 2>/dev/null /sbin/ip link set dev ${DEVICE} up /sbin/ip addr add dev ${DEVICE} ${IPADDR}/${NETBITS} /sbin/iptables -I POSTROUTING -t nat -j MASQUERADE -s ${IPADDR}/${NETBITS} /sbin/sysctl net.ipv4.ip_forward=1 /sbin/iptables -I FORWARD -s ${IPADDR}/${NETBITS} -j ACCEPT /sbin/iptables -I FORWARD -d ${IPADDR}/${NETBITS} -j ACCEPT
Set /etc/sysconfig/network-scripts/ifdown-usb:
#!/bin/bash . /etc/init.d/functions cd /etc/sysconfig/network-scripts . ./network-functions [ -f ../network ] && . ../network CONFIG=${1} need_config ${CONFIG} source_config NETBITS=`ipcalc -p ${IPADDR} ${NETMASK} | awk -F'=' '{print $2;}'` /sbin/iptables -D FORWARD -d ${IPADDR}/${NETBITS} -j ACCEPT /sbin/iptables -D FORWARD -s ${IPADDR}/${NETBITS} -j ACCEPT /sbin/sysctl net.ipv4.ip_forward=0 /sbin/iptables -D POSTROUTING -t nat -j MASQUERADE -s ${IPADDR}/${NETBITS} /sbin/ip link set dev ${DEVICE} down /sbin/ip addr flush dev ${DEVICE} 2>/dev/null
If you are using NetworkManager, restart it and enable the usb device from its menu, otherwise it will disable your connection shortly after you enable it.
/sbin/service NetworkManager restart
Edit /etc/sysconfig/network-scripts/net.hotplug:
After this command:
case $INTERFACE in # interfaces that are registered after being "up" (?)
add
usb0) ifconfig usb0 192.168.0.200 netmask 255.255.255.0 route add 192.168.0.202 usb0 iptables -I INPUT 1 -s 192.168.0.202 -j ACCEPT iptables -I OUTPUT 1 -s 192.168.0.200 -j ACCEPT iptables -A POSTROUTING -t nat -j MASQUERADE -s 192.168.0.0/24 echo 1 > /proc/sys/net/ipv4/ip_forward exit 0 ;;
Open /etc/conf.d/net and add:
# Neo config_usb0=( "192.168.0.200 netmask 255.255.255.0" ) routes_usb0=( "192.168.0.202/32 via 192.168.0.200" )
Create a new init script:
cd /etc/init.d ln -s net.lo net.usb0
Put iptables into use:
iptables -I INPUT 1 -s 192.168.0.202 -j ACCEPT iptables -I OUTPUT 1 -s 192.168.0.200 -j ACCEPT iptables -A POSTROUTING -t nat -j MASQUERADE -s 192.168.0.0/24
Store them:
/etc/init.d/iptables save
If you want the routing by default:
rc-update add iptables default
You must also inform the kernel, to start forwarding.
echo 1 > /proc/sys/net/ipv4/ip_forward
One way to automate all this is to create /etc/conf.d/net.usb0 as follows. It sets IP forwarding and the iptables rules all in one go. It removes the iptables rules and disables ip forwarding when the FreeRunner is unplugged.
preup() { echo 1 > /proc/sys/net/ipv4/ip_forward iptables -I INPUT 1 -s 192.168.0.202 -j ACCEPT iptables -I OUTPUT 1 -s 192.168.0.200 -j ACCEPT iptables -A POSTROUTING -t nat -j MASQUERADE -s 192.168.0.0/24 return 0 } postdown() { echo 0 > /proc/sys/net/ipv4/ip_forward iptables -D INPUT -s 192.168.0.202 -j ACCEPT iptables -D OUTPUT -s 192.168.0.200 -j ACCEPT iptables -D POSTROUTING -t nat -j MASQUERADE -s 192.168.0.0/24 return 0 }
See the USB Networking section in the MacOS X article.
See the USB Ethernet emulation section in the Neo1973 and Windows article.
Instead of using the IP address, instead enter in your desktop's /etc/hosts:
192.168.0.202 openmoko
Then instead type:
ssh root@openmoko
If you move about, making assumptions about the network may not be convenient, and it is possible to proxy DNS requests via your host laptop (which you are also taking with you). There are a number of ways to do this:
The script is designed to use dnrd as the DNS proxy. The script and a copy of dnrd are available. The script also performs the initial setup of the connection as per the USB_Networking#Manual_method above.
Another easy setup is using a UDP forwarder like the one from http://www.tapor.com/udpf/ - use it with the command"
udpf-elf -p=53-f=`cat /etc/resolv.conf|awk '$1 == "nameserver"{print $2; exit(0);}'`:53
It is possible to forward DNS requests with iptables using the DNAT target:
iptables -t nat -A PREROUTING -p tcp -s 192.168.0.202 -d 192.168.0.200 --dport domain -j DNAT --to-destination 192.168.0.1 iptables -t nat -A PREROUTING -p udp -s 192.168.0.202 -d 192.168.0.200 --dport domain -j DNAT --to-destination 192.168.0.1
Where 192.168.0.1 is the IP of your router.
Reportedly, the ssh daemon (dropbear 0.49) on the FreeRunner appears to have a bug when sending the exit status back to the client. From time to time you receive an exit status of 255.
To avoid ssh added a new line for every ssh host-key to you known_hosts you can add the following to the phone section in ~/.ssh/config
UserKnownHostsFile /dev/null
You might want to use keys to bypass the login prompt too.
To generate ssh keys for use as a login mechanism type:
ssh-keygen -t rsa
When prompted for a password either hit enter for no password (not really a good idea) or enter a password for this key. ssh into the phone and create ~/.ssh:
# mkdir ~/.ssh
Then from your desktop copy the .pub file to the phone.
# scp ~/.ssh/id_rsa.pub phone:.ssh/authorized_keys
You should now be able to ssh directly into the phone without a password prompt.
To disable password logins (after setting up key access) edit /etc/init.d/dropbear and change the following line:
DROPBEAR_EXTRA_ARGS=
to
DROPBEAR_EXTRA_ARGS="-s"
You will need to restart dropbear for this to take effect.
Generate the key:
dropbearkey -t rsa -f id_rsa
The output will look something like this:
Will output 1024 bit rsa secret key to 'id_rsa' Generating key, this may take a while... Public key portion is: ssh-rsa AAAAB3Nza[...] Fingerprint: md5 ca:e8:f0:b7:f6:7b:c2:b6:b9:71:e4:45:86:a9:ff:b8
Copy and paste the one line (in this example, starting with 'ssh-rsa' onto the end of the host's authorized_keys file (often in ~/.ssh/).
From the phone, ssh with -i:
ssh -i id_rsa user@host
If you reflash, your hosts keys will change. Try this ~/.ssh/config snippet:
Host moko HostName 192.168.0.202 StrictHostKeyChecking no UserKnownHostsFile /dev/null User root
This is suggested because ssh on your desktop may complain if the key matching a certain IP changes (stored in .ssh/known_hosts).
To get the GUI on the FreeRunner onto the desktop via USB, you can use ssh as follows:
ssh -l root -X -v 192.168.0.202
Using this, run openmoko-finger-demo for example, and it will open up on the desktop. To get landscape view, just resize the GUI window on the desktop.
If you get an error like this:
dbus.exceptions.DBusException: org.freedesktop.DBus.Error.Spawn.ExecFailed: dbus-launch failed to autolaunch D-Bus session: Autolaunch requested, but X11 support not compiled in.
you need to set the DBUS_SESSION_BUS_ADDRESS environment variable to the value on the Freerunner before launching the process from your desktop. You can find the value of this variable by using a command such as
ps auxwwwwe | grep -m 1 DBUS_SESSION_BUS_ADDRESS
Note that you must run that command on the Freerunner. Back on your desktop, run the process you want with the env command like this:
env DBUS_SESSION_BUS_ADDRESS=dbus_address process
To get desktop apps to show up on your FreeRunner, first log in:
ssh -l root 192.168.0.202
Then run:
DISPLAY=:0 xhost +192.168.0.200
After this you can close the ssh session. Back on the desktop computer, run:
DISPLAY=openmoko:0 xclock
Note that the xhost command will allow remote applications on 192.168.0.200 to access the X server. It will allow anyone on the desktop machine to access the X server of the neo, including snooping anything you type on it. To disallow remote applications again, run this in the neo:
DISPLAY=:0 xhost -192.168.0.200
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