2006-17-04
| Revision History | ||
|---|---|---|
| Revision 1.5b | 2006-17-04 | LKS |
| Note! To be completed. Updated to MIPL release 2.0.1 (kernel 2.6). Major update. | ||
| Revision 1.2 | 2004-04-20 | LKS |
| Updated links. Changed lisence back to GFDL | ||
| Revision 1.1 | 2004-02-04 | LKS |
| Added "Travelling through several foregin LAN's" and "Returning home". Some cleanup and restructuring. | ||
| Revision 1.0 | 2003-12-02 | TMM |
| Reviewed by LDP | ||
| Revision 0.5.2 | 2003-11-26 | LKS |
| A lot of cleanup. Thanks to John Levon levon [at] movementarian.org | ||
| Revision 0.5.1 | 2003-11-22 | LKS |
| Changed the license from GFDL to OPL due to some GFDL problems. | ||
| Revision 0.5 | 2003-11-18 | LKS |
| Converted to XML Docbook. Some cleanup. | ||
| Revision 0.4 | 2002-11-07 | LKS |
| Fixed some errors + update. Thanks to Henrik Petander petander (at) tcs hut fi. | ||
| Revision 0.3.1 | 2003-11-03 | LKS |
| Updated to MIPL relase 1.0 (kernel 2.4.22). | ||
| Revision 0.3 | 2003-08-05 | LKS |
| Initial release. | ||
Abstract
This document describes the software and procedures to set up and use mobile IPv6 for Linux.
Table of Contents
This document describes the software and procedures to set up and use mobile IPv6 for Linux. The RFC3775: "Mobility Support in IPv6" answers the what and why of mobile IP:
“Each mobile node is always identified by its home address, regardless of its current point of attachment to the Internet. While situated away from its home, a mobile node is also associated with a care-of address, which provides information about the mobile node's current location. IPv6 packets addressed to a mobile node's home address are transparently routed to its care-of address. The protocol enables IPv6 nodes to cache the binding of a mobile node's home address with its care-of address, and to then send any packets destined for the mobile node directly to it at this care-of address.” --- RFC3775, page 1.
“Without specific support for mobility in IPv6 [RFC2460], packets destined to a mobile node would not be able to reach it while the mobile node is away from its home link. In order to continue communication in spite of its movement, a mobile node could change its IP address each time it moves to a new link, but the mobile node would then not be able to maintain transport and higher-layer connections when it changes location. Mobility support in IPv6 is particularly important, as mobile computers are likely to account for a majority or at least a substantial fraction of the population of the Internet during the lifetime of IPv6.” --- RFC3775, page 5.
For all the details, read RFC3775: "Mobility Support in IPv6"
The Mobile Node (MN) travels to a foreign network and gets a new care-of-address.
The MN performs a binding update to its Home Agent (HA) (the new care-of-address gets registered at HA). HA sends a binding acknowledgement to MN.
A Correspondent Node (CN) wants to contact the MN. The HA intercepts packets destined to the MN.
The HA then tunnels all packets to the MN from the CN using MN's care-of-address.
When the MN answers the CN, it may use its current care-of-address (and perform a binding to the CN) and communicate with the CN directly (“route optimization”) or it can tunnel all its packets through the HA.
See figure "Mobile IP" for an explanation.
IP version 6 (IPv6) is a new version of the Internet Protocol, designed as the successor to IP version 4 (IPv4) [RFC791]. The changes from IPv4 to IPv6 fall primarily into the following categories:
Expanded addressing capabilities
Header format simplification
Improved support for extensions and options
Flow labeling capability
Authentication and privacy capabilities
You should have basic knowledge of IPv6 stateless auto-configuring to fully understand how “mobile IPv6” (MIPv6) works. You can read up on IPv6 Stateless Address Autoconfiguration in [RFC2462].
For more information on IPv6 in general, visit the IETF's IPv6 Working Group.
The Helsinki University of Technology MIPL project are behind the only up-to-date Mobile IPv6 implementation for Linux. The latest kernel supported is 2.6.15 and is compatible with RFC3775. Visit http://www.mobile-ipv6.org/ for papers, software or to browse the mail archive.
The implementation includes both a kernel modification (a kernel patch) and user space software.
Caution
Patching and recompiling the kernel can easily render your system unbootable. If you've never done this before, I strongly suggest you take a look at the Linux Kernel HOWTO.
The MIPL MIPv6 implementation requires a kernel patch. The implementation modifies the IPv6 kernel stack, so a kernel recompile is necessary. The installation process is well documented, but I will give a brief step-by-step howto.
Both the Mobile Node (MN) and Home Agent (HA) needs their kernel patched, but they do not require all the same kernel options. Details below.
Download the latest Linux MIPv6 source code from http://mobile-ipv6.org/. The latest release today is: mipv6-2.0-v2.6.15. The last four numbers corresponds to the Linux kernel the patch should be applied to:
#cd /usr/local/src#wget http://mobile-ipv6.org/download/mipv6-2.0-v2.6.15.tar.gz#tar zxfv mipv6-1.0-v2.4.22.tar.gzDownload and unpack the correspondent Linux kernel version from ftp.kernel.org:
#cd /usr/src#wget ftp://ftp.kernel.org/pub/linux/kernel/v2.6/linux-2.6.15.tar.bz2#tar jxvf linux-2.6.15.tar.bz2#ln -s linux-2.5.16 linux#cd linuxApply the MIPv6 patch:
#zcat /usr/local/src/mipv6-2.0.1-linux-2.6.15.patch.gz | patch -p1 --dry-runWarning
If you get any “failed chunks” (errors/warnings), do not proceed. Go carefully over the above step once more.
The --dry-run option checks that the patch will apply correctly. If everything went fine do:
#zcat /usr/local/src/mipv6-2.0.1-linux-2.6.15.patch.gz | patch -p1Now your kernel tree is ready for configuration. Run your favorite make *config. The MIPv6 options are under “Networking Options”. Depending on whether the node should act as a Mobile Node or Home Agent or whether you want to use IPSec, the options in the .config file differs:
Make sure these options are present:
CONFIG_EXPERIMENTAL=y CONFIG_SYSVIPC=y CONFIG_PROC_FS=y CONFIG_NET=y CONFIG_INET=y CONFIG_IPV6=y CONFIG_IPV6_MIP6=y CONFIG_XFRM=y CONFIG_XFRM_USER=y CONFIG_XFRM_ENHANCEMENT=y CONFIG_IPV6_TUNNEL=y CONFIG_IPV6_ADVANCED_ROUTER=y CONFIG_IPV6_MULTIPLE_TABLES=yThe Mobile Node also needs:
CONFIG_IPV6_SUBTREES=y CONFIG_ARPD=yWe want to enable IPSec, so we also need:
CONFIG_INET6_ESP=y CONFIG_NET_KEY=y CONFIG_NET_KEY_MIGRATE=yTo be sure you have all the correct options, you can run
chkconf_kernel.sh, which is a small shell script included in the MIPL tarball. If the script reports any missing options, fix it before you proceed.#./chkconf_kernel.sh /usr/src/linuxChecking kernel configuration... Using /usr/src/linux/.config All kernel options are as they should.Next you should compile and install your kernel.
Tip
Hint: To easily distinguish this kernel from other kernels, you can change the “EXTRAVERSION” variable in the
/usr/src/linux/Makefileto for example “-MIPv6-1”.
Read the Linux Kernel HOWTO for detailed instruction on how to patch, compile and install your new kernel.
The userspace tool mip6d, config files and init scripts must be installed for the module to work correctly:
Download and unpack the user space soure code:
# cd /usr/local/src/
# wget http://mobile-ipv6.org/software/download/mipv6-2.0.1.tar.gz
# tar zxfv mipv6-2.0.1.tar.gz
# cd mipv6-2.0.1
Next, configure, compile and install the source code. Note that we include the --enable-vt option to configure. This option is not required, but will provide us with helpful information. It will enable a virtual terminal listning on localhost port 7777.
# CPPFLAGS=-I/usr/src/linux/include ./configure --enable-vt
# make
# make install
The documentation mention that there is a set of init (startup) scripts available under the extra/ directory. I could only find some example configuration files there. Below is a init script for Debian and Ubuntu. It should be a small effort to make this work on other distributions as well.
All init scripts are located under
/etc/init.d and symlinked to correct runlevel
(/etc/rcX.d).
Note
Note that this script override and sets the verbosity level to 0.
#!/bin/sh
#
# mip6d: Starts the Mobile IPv6 Daemon
#
# description: This is a daemon which provide IPv6 Mobility
# support (RFC3775). Init script for Debian and Ubuntu.
#
# (C) GNU GPL Lars Strand <lars strand at linpro no>
#
PATH=/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/sbin
DAEMON=/usr/local/sbin/mip6d
DESC=mip6d
CONFIG=/etc/mip6d.conf
OPTIONS="-d 0 -c $CONFIG"
set -e
# Check for IPv6 support in kernel
if [ ! -e /proc/sys/net/ipv6 ]; then
echo "IPv6 support must be enabled in the kernel for $DESC to work."
exit 1
fi
# Can we fint the mip6d?
if [ ! -x $DAEMON ]; then
echo "Unable to find $DAEMON."
exit 1
fi
chkconfig() {
if [ ! -e $CONFIG -o ! -s $CONFIG ]; then
echo ""
echo "ERROR: $CONFIG does not exist or is empty."
echo " See mip6d.conf(5) for configuration file syntax and example"
echo " configuration. $DESC will *not* be started."
echo ""
exit 1
fi
}
# See how we were called.
case "$1" in
start)
echo -n "Starting $DESC..."
chkconfig
if ! start-stop-daemon --oknodo --start --exec $DAEMON -- $OPTIONS; then
echo "failed." && exit 1
fi
echo " done."
;;
stop)
echo -n "Stopping $DESC..."
start-stop-daemon --oknodo --stop --exec $DAEMON
echo " done."
;;
restart)
chkconfig
echo -n "Restarting $DESC..."
start-stop-daemon --oknodo --stop --exec $DAEMON
sleep 1
start-stop-daemon --oknodo --start --exec $DAEMON -- $OPTIONS
echo " done."
;;
*)
echo "Usage: $0 {start|stop|restart}" >&2
exit 1
;;
esac
exit 0
Now you should have a working MIPv6 patched kernel, installed userlevel tools and enabled automatic startup at boot. If anything went wrong, go through the above sections carefully.
The addresses we are using in our test-bed are site-local. You may as well use global addresses, but do note that link local addresses won't work! Our test-bed consist of four nodes; see figure "Mobile IPv6 testbed".
HA - Home Agent: The HA is located at the home network with address
fec0:106:2700::2, with one wireless interface.MN - Mobile Node: When MN is on the “home network”, it has address
fec0:106:2700::4. When MN travels to another network, it generates a new “care-of” address.R - Router: This is the router from the home network to the internet. It has one wireless interface with address
fec0:106:2700::1and a wired interface with addressfec0:106:2300::2.AR - Access Router: The link between AR and R is our “internet” - but in this testcase only a cross-cable (can be any network). The AR has two interfaces; the wired interface to R has address
fec0:106:2300::1, the wireless has addressfec0:106:1100::1.
Before we can start testing mobile IP, we need a fully functional IPv6 network.
Note
All the nodes should be able to ping each other. This is a crucial part. If, for example, AR is not able to ping HA, then there will be no binding update.
I will give a brief instruction to get our network up and running using IPv6. For more info on setting up an IPv6 network, you can read Peter Bieringer's excellent Linux IPv6 HOWTO.
I've turned off wireless encryption for simplicity - NOTE that you should ALWAYS use encryption when dealing with wireless networks!
Also note that the different wireless networks have different ESSIDs!
MN: The Mobile Node has one wireless interface. Forwarding should be turned off, but should accept autoconf and ra's:
#iwconfig eth0 mode ad-hoc essid homenet enc off#ifconfig eth0 inet6 add fec0:106:2700::4/64#echo 0 > /proc/sys/net/ipv6/conf/eth0/forwarding#echo 1 > /proc/sys/net/ipv6/conf/eth0/autoconf#echo 1 > /proc/sys/net/ipv6/conf/eth0/accept_ra#echo 1 > /proc/sys/net/ipv6/conf/eth0/accept_redirectsHA: The Home Agent has one wireless interface. It should have forwarding turned on because it uses normal routing to deliver packets captured from a physical interface to the virtual tunnel interface. Note: You must add a default route or else HA will have problem contacting the MN on visited LAN's. One possible solution is to use HA as the default router of the home network.
#iwconfig eth0 mode ad-hoc essid homenet enc off#ifconfig eth0 inet6 add fec0:106:2700::2/64#echo 1 > /proc/sys/net/ipv6/conf/eth0/forwarding#echo 0 > /proc/sys/net/ipv6/conf/eth0/autoconf#echo 0 > /proc/sys/net/ipv6/conf/eth0/accept_ra#echo 0 > /proc/sys/net/ipv6/conf/eth0/accept_redirects#ip route add ::/0 via fec0:106:2700::1R: The (home) Router has two interfaces; one wireless and one line. The Router must have forwarding turned on.
#ifconfig eth0 inet6 add fec0:106:2300::2/64#iwconfig eth1 mode ad-hoc essid homenet enc off#ifconfig eth1 inet6 add fec0:106:2700::1/64#echo 1 > /proc/sys/net/ipv6/conf/all/forwarding#echo 0 > /proc/sys/net/ipv6/conf/all/autoconf#echo 0 > /proc/sys/net/ipv6/conf/all/accept_ra#echo 0 > /proc/sys/net/ipv6/conf/all/accept_redirects#ip route add fec0:106:1100::/64 via fec0:106:2300::1AR: The Access Router (on a foreign network) also has two interfaces; one wireless and one line. Forwarding must be turned on.
#ifconfig eth0 inet6 add fec0:106:2300::1/64#iwconfig eth1 mode ad-hoc essid visitnet enc off#ifconfig eth1 inet6 add fec0:106:1100::1/64#echo 1 > /proc/sys/net/ipv6/conf/all/forwarding#echo 0 > /proc/sys/net/ipv6/conf/all/autoconf#echo 0 > /proc/sys/net/ipv6/conf/all/accept_ra#echo 0 > /proc/sys/net/ipv6/conf/all/accept_redirects#ip route add fec0:106:2700::/64 via fec0:106:2300::2
Instead of modifying proc variables, you can use sysctl.
Note: We are setting static routes on our test-bed. You should now be able to ping all the hosts from every host.
When you issue make install, neither init
script nor configuration file is installed. Example configuration
files are found under the extra/ directory
under the source code. You may also consult
mip6d.conf(5) man page. The file should be
pretty self-explanatory.
HA: The HA config file should contain these settings:
# Mobile IPv6 configuration file: Home Agent # # filename: /etc/mip6d.conf NodeConfig HA; ## If set to > 0, will not detach from tty DebugLevel 10; ## List of interfaces where we serve as Home Agent Interface "eth0"; ## ## IPsec configuration ## UseMnHaIPsec enabled; IPsecPolicySet { HomeAgentAddress fec0:106:2700::2; HomeAddress fec0:106:2700::2/64; IPsecPolicy HomeRegBinding UseESP; IPsecPolicy MobPfxDisc UseESP; IPsecPolicy TunnelMh UseESP; }MN: The MN config file should look like this:
# Mobile IPv6 configuration file: Mobile Node # # filename: /etc/mip6d.conf NodeConfig MN; ## If set to > 0, will not detach from tty DebugLevel 10; MnDiscardHaParamProb enabled; Interface "eth0"; MnHomeLink "eth0" { HomeAgentAddress fec0:106:2700::2; HomeAddress fec0:106:2700::4/64; } ## ## IPsec configuration ## UseMnHaIPsec enabled; IPsecPolicySet { HomeAgentAddress fec0:106:2700::2; HomeAddress fec0:106:2700::4/64; IPsecPolicy HomeRegBinding UseESP; IPsecPolicy MobPfxDisc UseESP; IPsecPolicy TunnelMh UseESP; }
When MN comes to a new network, it does a link-local address configuration, going to the next phase if that succeeds. I'll let [RFC2462] (IPv6 Stateless Address Autoconfiguration) describe the next phase:
“The next phase of autoconfiguration involves obtaining a Router Advertisement or determining that no routers are present. If routers are present, they will send Router Advertisements that specify what sort of autoconfiguration a host should do. If no routers are present, stateful autoconfiguration should be invoked.”
“Routers send Router Advertisements periodically, but the delay between successive advertisements will generally be longer than a host performing autoconfiguration will want to wait. To obtain an advertisement quickly, a host sends one or more Router Solicitations to the all-routers multicast group.” --- page 8
This is where we use Linux IPv6 Router Advertisement Daemon (RADVD).
Read [RFC2462] more more details concerning IPv6 Stateless Address Autoconfiguration.
We'll configure RADVD on AR's wireless interface. The
radvd.conf file should contain this:
# cat /etc/radvd.conf
interface eth1
{
AdvSendAdvert on;
AdvIntervalOpt on;
MinRtrAdvInterval 3;
MaxRtrAdvInterval 10;
AdvHomeAgentFlag off;
prefix fec0:106:1100::/64
{
AdvOnLink on;
AdvAutonomous on;
AdvRouterAddr on;
};
};
We then start it:
# /etc/init.d/radvd start
You should now be able to use radvdump to
see that the radvd messages really are being sent periodically:
# radvdump
Router advertisement from fe80::202:2dff:fe54:d1b2 (hoplimit 255)
Received by interface eth1
# Note: {Min,Max}RtrAdvInterval cannot be obtained with radvdump
AdvCurHopLimit: 64
AdvManagedFlag: off
AdvOtherConfigFlag: off
AdvHomeAgentFlag: off
AdvReachableTime: 0
AdvRetransTimer: 0
Prefix fec0:106:1100::/64
AdvValidLifetime: 2592000
AdvPreferredLifetime: 604800
AdvOnLink: on
AdvAutonomous: on
AdvRouterAddr: off
AdvSourceLLAddress: 00 02 2D 54 D1 B2
Note
When using radvd on HA and enabling “autoconf” (in proc), you will also get an autogenerated IPv6 address on MN (which is superfluous) in addition to your static address:
To enable the MN to know when it's home, HA should also be sending
out RAs. We should therefore enable RADVD on the HA as well. The
/etc/radvd.conf file should contain:
# cat /etc/radvd.conf
interface eth0
{
AdvSendAdvert on;
MaxRtrAdvInterval 3;
MinRtrAdvInterval 1;
AdvIntervalOpt off;
AdvHomeAgentFlag on;
HomeAgentLifetime 10000;
HomeAgentPreference 20;
AdvHomeAgentInfo on;
prefix fec0:106:2700::2/64
{
AdvRouterAddr on;
AdvOnLink on;
AdvAutonomous on;
AdvPreferredLifetime 10000;
AdvValidLifetime 12000;
};
};
Also do a radvdump on HA to check
whether radvd messages are beeing sent:
# radvdump
Router advertisement from fe80::202:2dff:fe54:d11e (hoplimit 255)
Received by interface eth0
# Note: {Min,Max}RtrAdvInterval cannot be obtained with radvdump
AdvCurHopLimit: 64
AdvManagedFlag: off
AdvOtherConfigFlag: off
AdvHomeAgentFlag: on
AdvReachableTime: 0
AdvRetransTimer: 0
Prefix fec0:106:2700::2/64
AdvValidLifetime: 12000
AdvPreferredLifetime: 10000
AdvOnLink: on
AdvAutonomous: on
AdvRouterAddr: on
AdvSourceLLAddress: 00 02 2D 54 D1 1E
AdvHomeAgentInfo:
HomeAgentPreference: 20
HomeAgentLifetime: 1000
Also, you'll notice that MN (when home) generates a new address based on RADVD messages:
# ifconfig eth0
eth0 Link encap:Ethernet HWaddr 00:90:7D:F3:03:1A
inet6 addr: fec0:106:2700::4/64 Scope:Site 
inet6 addr: fe80::290:7dff:fef3:31a/64 Scope:Link 
inet6 addr: fec0:106:2700:0:290:7dff:fef3:31a/64 Scope:Site 
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:513 errors:89 dropped:89 overruns:0 frame:85
TX packets:140 errors:41 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
RX bytes:56084 (54.7 Kb) TX bytes:19212 (18.7 Kb)
Interrupt:3 Base address:0x100
| | Our original static IPv6 address |
| | The link-local address generated at boot. |
| |
A new (superfluous) autogenerated address. Since we are
setting |
Start Mobile IPv6 on HA. We do not use the init scripts when we do the testing. We want to view the verbosity messages:
#mip6d -c /etc/mip6d.confmip6d[3794]: MIPL Mobile IPv6 for Linux v2.0.1 started (Home Agent)
main: MIPL Mobile IPv6 for Linux started in debug mode, not detaching from terminal
conf_show: config_file = /etc/mip6d.conf
conf_show: vt_hostname = localhost
conf_show: vt_service = 7777
conf_show: mip6_entity = 2
conf_show: debug_level = 10
conf_show: PolicyModulePath = [internal]
conf_show: DefaultBindingAclPolicy = 0
conf_show: NonVolatileBindingCache = disabled
conf_show: KeyMngMobCapability = disabled
conf_show: UseMnHaIPsec = enabled
conf_show: MnMaxHaBindingLife = 262140
conf_show: MnMaxCnBindingLife = 420
conf_show: MnRouterProbes = 0
conf_show: MnRouterProbeTimeout = 0.000000
conf_show: InitialBindackTimeoutFirstReg = 1.500000
conf_show: InitialBindackTimeoutReReg = 1.000000
conf_show: UseCnBuAck = disabled
conf_show: DoRouteOptimizationMN = enabled
conf_show: MnUseAllInterfaces = disabled
conf_show: MnDiscardHaParamProb = disabled
conf_show: SendMobPfxSols = enabled
conf_show: SendMobPfxAdvs = enabled
conf_show: SendUnsolMobPfxAdvs = enabled
conf_show: MaxMobPfxAdvInterval = 86400
conf_show: MinMobPfxAdvInterval = 600
conf_show: HaMaxBindingLife = 262140
conf_show: DoRouteOptimizationCN = enabled
xfrm_cn_init: Adding policies and states for CN
xfrm_ha_init: Adding policies and states for HA
vt_server_init: VT server listens 127.0.0.1[7777] OK 
The node is acting as a HA.
The configuration file is
/etc/mip6d.conf We are using IPSec.
A VT server listning on localhost port 7777.
Next we start Mobile IPv6 on MN. As with HA, we want the verbose messages, so we do not use the init script.
#mip6d -c /etc/mip6d.confmip6d[9121]: MIPL Mobile IPv6 for Linux v2.0.1 started (Mobile Node)
main: MIPL Mobile IPv6 for Linux started in debug mode, not detaching from terminal
conf_show: config_file = /etc/mip6d.conf
conf_show: vt_hostname = localhost
conf_show: vt_service = 7777
conf_show: mip6_entity = 1
conf_show: debug_level = 10
conf_show: PolicyModulePath = [internal]
conf_show: DefaultBindingAclPolicy = 0
conf_show: NonVolatileBindingCache = disabled
conf_show: KeyMngMobCapability = disabled
conf_show: UseMnHaIPsec = enabled
conf_show: MnMaxHaBindingLife = 262140
conf_show: MnMaxCnBindingLife = 420
conf_show: MnRouterProbes = 0
conf_show: MnRouterProbeTimeout = 0.000000
conf_show: InitialBindackTimeoutFirstReg = 1.500000
conf_show: InitialBindackTimeoutReReg = 1.000000
conf_show: UseCnBuAck = disabled
conf_show: DoRouteOptimizationMN = enabled
conf_show: MnUseAllInterfaces = disabled
conf_show: MnDiscardHaParamProb = enabled
conf_show: SendMobPfxSols = enabled
conf_show: SendMobPfxAdvs = enabled
conf_show: SendUnsolMobPfxAdvs = enabled
conf_show: MaxMobPfxAdvInterval = 86400
conf_show: MinMobPfxAdvInterval = 600
conf_show: HaMaxBindingLife = 262140
conf_show: DoRouteOptimizationCN = enabled
xfrm_cn_init: Adding policies and states for CN
xfrm_mn_init: Adding policies and states for MN
conf_home_addr_info: HoA address fec0:106:2700:0:0:0:0:4
conf_home_addr_info: HA address fec0:106:2700:0:0:0:0:2
__tunnel_add: created tunnel ip6tnl1 (17) from fec0:106:2700:0:0:0:0:4 to fec0:106:2700:0:0:0:0:2 user count 1
conf_home_addr_info: Home address fec0:106:2700:0:0:0:0:4
flag_hoa: set HoA fec0:106:2700:0:0:0:0:4/128 iif 17 flags 10 preferred_time 4294967295 valid_time 4294967295
conf_home_addr_info: Added new home_addr_info successfully
__md_discover_router: discover link on iface eth0 (4)
vt_server_init: VT server listens 127.0.0.1[7777] OK 
md_change_default_router: add new router fe80:0:0:0:201:2ff:fef1:91ee on interface eth1 (4)
mn_addr_do_dad: DAD succeeded!
mn_move: 1535
mn_move: in home net 
mv_hoa: move HoA fec0:106:2700:0:0:0:0:4/64 from iface 17 to 4
The node is acting as a MN.
The configuration file is
/etc/mip6d.conf We are using IPSec.
The next lines shows Home Address (HoA) and Home Agent address (HA). Further down it creates a IPv6 tunnel.
A VT server listning on localhost port 7777.
The node detects that it's on the home network and changed the Home Address (HoA) from the tunnel (ip6tnl1) to the actual interface (eth0).
Also when we issue the ifconfig, we'll notice the tunnel (ip6tnl1) is up:
#ifconfigeth0 Link encap:Ethernet HWaddr 00:90:7D:F3:03:1A inet6 addr: fec0:106:2700::4/64 Scope:Site inet6 addr: fe80::290:7dff:fef3:31a/64 Scope:Link inet6 addr: fec0:106:2700:0:290:7dff:fef3:31a/64 Scope:Site UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:513 errors:89 dropped:89 overruns:0 frame:85 TX packets:140 errors:41 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:100 RX bytes:56084 (54.7 Kb) TX bytes:19212 (18.7 Kb) Interrupt:3 Base address:0x100 ip6tnl1 Link encap:UNSPEC HWaddr FE-C0-01-06-27-00-00-00-00-00-00-00-00-00-00-00
inet6 addr: fe80::211:43ff:fecc:279c/64 Scope:Link
UP POINTOPOINT RUNNING NOARP MTU:1460 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:20352 errors:0 dropped:0 overruns:0 frame:0
TX packets:20352 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:1840264 (1.7 MiB) TX bytes:1840264 (1.7 MiB)
Tunnel is up and ready for connections.
Do every configuration as shown above; it's especially important to have a different ESSID on the home net and visited network.
When you start mobile-IPv6 on MN, you will see multicast router solicitations messages from RADVD:
# tcpdump -i eth0 -vv ip6 or proto ipv6
...
13:32:54.681763 fe80::202:a5ff:fe6f:a08a > ff02::2: icmp6: router solicitation \
(src lladdr: 0:2:a5:6f:a0:8a) (len 16, hlim 255)
13:32:55.681763 fe80::202:a5ff:fe6f:a08a > ff02::2: icmp6: router solicitation \
(src lladdr: 0:2:a5:6f:a0:8a) (len 16, hlim 255)
13:32:57.681765 fe80::202:a5ff:fe6f:a08a > ff02::2: icmp6: router solicitation \
(src lladdr: 0:2:a5:6f:a0:8a) (len 16, hlim 255)
...
Generic movement detection uses Neighbor Unreachability Detection to detect when the default router is no longer bi-directionally reachable, in which case the mobile node must discover a new default router (usually on a new link).
To easily see whats going on, you should have one xterm window for each of these commands (on MN):
# watch ifconfig eth0
# watch route -A inet6
# tcpdump -i eth0 -vv ip6 or proto ipv6
To “travel” to another net, you can issue the command on MN:
# iwconfig eth1 essid visitnet
The MN is then on the other wireless network, and since it is sending out “router solicitation” (multicast), our AR will respond with it's prefix. MN will then configure itself with at new IPv6 address with the received prefix and it's own MAC address. If you type ifconfig eth0 you will see the new IPv6 address:
# ifconfig eth0
eth0 Link encap:Ethernet HWaddr 00:90:7D:F3:03:1A
inet6 addr: fec0:106:1100:0:290:7dff:fef3:31a/64 Scope:Site
inet6 addr: fec0:106:2700:0:290:7dff:fef3:31a/64 Scope:Site
inet6 addr: fec0:106:2700::4/64 Scope:Site
inet6 addr: fe80::290:7dff:fef3:31a/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:854 errors:154 dropped:154 overruns:0 frame:148
TX packets:293 errors:58 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
RX bytes:96536 (94.2 Kb) TX bytes:44664 (43.6 Kb)
Interrupt:3 Base address:0x100
| | The new “foreign” address, generated by combining AR's prefix and MAC-address |
| | The superfluous home network address (because of HA radvd messages and MN autoconf set to “true”). |
| | The “original” (home) address |
| | The link-local address generated at boot |
To be completed.
To travel to several visited networks, is no different than travel to one network. The only thing you must have in mind is that you will generate a new address for each visited network.
MN first visits 'visitnet', as we have been through above.
MN is then travelling from 'visitnet' to 'visitnet2'.
When at 'visitnet2', MN generates a new IPv6 address and do a new binding update to HA.
MN then travels back home. (Se next section.)
The AR at “visitnet2”, is configured exactly
as the other AR (at “visitnet”), except using address
fec0:106:1000::/64 instead of
fec0:106:1100::/64.
To make the mobile node travel from “visitnet” to “visitnet2”, issue the command (on MN):
# iwconfig eth0 essid visitnet2
You will then see the MN configures itself to the new network:
# ifconfig eth0
eth1 Link encap:Ethernet HWaddr 00:90:7D:F3:03:1A
inet6 addr: fec0:106:1000:0:290:7dff:fef3:31a/64 Scope:Site
inet6 addr: fec0:106:1100:0:290:7dff:fef3:31a/64 Scope:Site
inet6 addr: fec0:106:2700:0:290:7dff:fef3:31a/64 Scope:Site
inet6 addr: fec0:106:2700::4/64 Scope:Site
inet6 addr: fe80::290:7dff:fef3:31a/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:1073 errors:212 dropped:212 overruns:0 frame:204
TX packets:371 errors:72 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
RX bytes:120340 (117.5 Kb) TX bytes:56912 (55.5 Kb)
Interrupt:3 Base address:0x100
| | The new autoconfigured address at 'visitnet2'. |
To be completed.
To make the MN return home, you can just issue the command:
# iwconfig eth0 essid homenet
The MN will know it is back home, since HA is sending out radvd messages with the HA-bit set (AdvHomeAgentFlag), see the section called “Configuring radvd on HA”
To be completed.
To really get the feel on how mobile IP works, fire up GnomeMeeting (See the figure GnomeMeeting and start a netmeeting. Note! You must use the latest GnomeMeeting to get support for IPv6! Then do a “travel” and you can see an almost smooth handover.
Q: Is it normal to use iwconfig eth0 essid visitnet to control handover?
A: No, it has nothing to do with Mobile IPv6. It is just as an example on how you can easily test that your setup works. ESSIDs are layer 2, while Mobile IPv6 is layer 3.
Q: Can different wireless networks have different ESSIDs/WEP keys?
A: Yes, but you must change this upon arrival to the new network. MIPv6 from MIPL can't do this automatically.
Q: If MN has travelled through several visited LAN, and then returning home; the interface still has all the autogenerated IPv6 addresses from all the visited networks! Is there any way to “flush/delete” these addresses?
A: No, I do not know of any automatic way these adresses can be removed, but you can delete them manually:
#ifconfig eth0 inet6 del <ipv6-address>Q: Host B has two interfaces with two different subnets assigned. When I ping B from host A, it does not answer! Why not? Host A knows where host B (subnets) are!
A: The host B doesn't know where host A is (B doesn't know where A's net is), so you must add a route entry:
#ip route add fec0:106:2700::/64 via fec0:106:2300::1or
#route -A inet6 add fec0:106:2700::/64 gw fec0:106:2300::1 dev eth0Q: How do I set a default gateway in IPv6?
A: You do that using the traditional “route”:
#route -A inet6 add default gw <ipv6-host>or the newer “ip” command:
#ip route ::/0 via <ipv6-host>Q: Why does the host send a multicast address rather than an anycast address, requesting for router solicitation?
A: Because the host wants an answer from every router, not from just any router. The idea is to be able to get all parameters and to choose the “best” default router.
Q: Why doesn't MN notice that it has moved?
A: It thinks that it's previous router is still reachable. This may result from very large lifetimes in router advertisements. Check the configuration of the program sending router advertisements in the router. If the program supports router advertisement intervals, you can use this to help MN in movement detection by setting the use of interval to
on. See radvd.conf(5) for details.
Mobile IPv6 for Linux http://mobile-ipv6.org/
Mobility for IPv6 (mip6) Working Group (IETF) http://www.ietf.org/html.charters/mip6-charter.html
IPv6 Working Group (IETF) http://www.ietf.org/html.charters/ipv6-charter.html
RFC2460: Internet Protocol, Version 6 (IPv6) Specification http://www.ietf.org/rfc/rfc2460.txt
RFC2461: Neighbor Discovery for IP Version 6 (IPv6) http://www.ietf.org/rfc/rfc2461.txt
RFC2462: IPv6 Stateless Address Autoconfiguration http://www.ietf.org/rfc/rfc2462.txt
RFC3775: Mobility Support in IPv6 http://www.ietf.org/rfc/rfc3775.txt
RFC3776: Using IPsec to Protect Mobile IPv6 Signaling Between Mobile Nodes and Home Agents http://www.ietf.org/rfc/rfc3776.txt
RFC3963: Network Mobility (NEMO) Basic Support Protocol http://www.ietf.org/rfc/rfc3963.txt
RFC4068: Fast Handovers for Mobile IPv6 http://www.ietf.org/rfc/rfc4068.txt
RFC4140: Hierarchical Mobile IPv6 Mobility Management (HMIPv6) http://www.ietf.org/rfc/rfc4140.txt
RFC4301: Security Architecture for the Internet Protocol http://www.ietf.org/rfc/rfc4301.txt
RFC4302: IP Authentication Header http://www.ietf.org/rfc/rfc4302.txt
RFC4303: IP Encapsulating Security Payload (ESP) http://www.ietf.org/rfc/rfc4303.txt
RFC4306: Internet Key Exchange (IKEv2) Protocol http://www.ietf.org/rfc/rfc4306.txt
Peter Bieringer's Linux IPv6 HOWTO (en) http://ldp.linux.no/HOWTO/Linux+IPv6-HOWTO/
Linux Kernel HOWTO http://www.tldp.org/HOWTO/Kernel-HOWTO/
Linux NEMO HOWTO http://www.nautilus6.org/doc/nepl-howto/
Current Status of IPv6 Support for Networking Applications http://www.deepspace6.net/docs/ipv6_status_page_apps.html
Copyright (c) 2003-2006 Lars Strand.
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License".
This document was originally written in LaTeX using Emacs. HTML version created with latex2html. Later it was converted to DocBook XML.
An up-to-date version of this document can be found at:
Suggestions, corrections, additions wanted. Contributors wanted and acknowledged. Flames not wanted.
I can always be reached at <lars at gnist
org>
Homepage: http://www.gnist.org/~lars
This document was produced as a part of Interoperable Networks for Secure Communications (INSC task 6)
Thanks to Andreas Hafslund (andreha [at] unik.no) for initial support. Also thanks to UniK (University Graduate Center) http://www.unik.no and FFI (Norwegian Defence Research Establishment) http://www.ffi.mil.no for hardware support.
Thanks also to the other HOWTO authors whose works I have referenced:
Linux IPv6 HOWTO (en) by Peter Bieringer
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