Lionel Gauthier
6430465801
git-svn-id: http://svn.eurecom.fr/openair4G/trunk@6052 818b1a75-f10b-46b9-bf7c-635c3b92a50f
81 lines
3.1 KiB
Plaintext
Executable File
81 lines
3.1 KiB
Plaintext
Executable File
Introduction
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------------
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This piece of software implementes GPRS Tunneling Protocol (GTP) for user plane.
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The software has two components - one is the extension of iptables that
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run in user-space. The other is the counterpart of the iptables extension
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that runs in kernel space.
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License
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-------
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The project is licensed under GPL2+, see the COPYING and AUTHORS files for more
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details.
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Architecture
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------------
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The GTPu tunneling is handled in two parts. The first part is the user-space
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iptables target extension library (let's call it libxt). The second
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part is the GTPu kernel loadable module (let's call it gtpu). The way it
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is, once the user configures a GTPu tunnel attributes using iptables, the klm
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is loaded by the kernel automatically and handles the IP packets according to
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the GTPu tunnel attributes set by the user.
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The user can set the action to be taken on a matching IP packet. The action can be
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either of "add", "remove" or "transport" .
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A GTPu tunnel has the following attributes:
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- own IP address
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- own GTPu tunnel id
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- peer's IP address
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- peer's GTPu tunnel id
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The GTPU target is designed to work only on mangle table. Also, the user is
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expected to add GTPU target to the PREROUTING chain, as the GTPU target will
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modify the original IP packet before it is routed.
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Once the user creates the rule in iptables, the matching IP packets go through
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the gtpu klm, which acts upon the IP packet according to the action set by the
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user. The action "Add" means the klm will add a GTPu header to the IP packet.
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"Remove" will remove the GTPu header from the IP packet and "Transport" will
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do a Remove first followed by an "Add" on the IP packet.
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For example, consider the following command:
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iptables -t mangle -A PREROUTING -d 10.10.10.1 -j GTPU --own-ip 192.168.0.98 --own-tun 100 --peer-ip 192.168.0.109 --peer-tun 101 --action add
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This command will configure the system to add a GTPu header to any IP packet destined to 10.10.10.1.
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The source IP address outer IP will be 192.168.0.109, the dest IP will be 192.168.0.98 and
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the destination GTP tunnel id will be 101.
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Similarly, consider the following command:
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iptables -t mangle -A PREROUTING -s 192.168.0.109 -d 192.168.0.98 -p udp --dport 2152 -j GTPU --action remove
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This command will process all the GTPu packets coming from 192.168.0.109 to 192.168.0.98 to
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strip the GTPu header and forward the inner IP packet to the kernel's routing engine.
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Files
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---------
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There are two source C files and one header file:
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- libxt_GTPU.c : source file for iptables GTPU extension library (libxt)
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- xt_GTPU.c : source file for gtpu kernel loadable module (klm)
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- xt_GTPU.h : common header file, shared between the libxt and the klm
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- Makefile : Makefile to build both the libxt and the klm
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- cmd.sh : sample cmd file to show how the binaries can be used
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See the INSTALL file to learn how to build the binaries.
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References
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----------
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3GPP TS 29.281 General Packet Radio System (GPRS)
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Tunnelling Protocol User Plane (GTP-u)
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Authors
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-------
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Pradip Biswas <pradip_biswas@polarisnetworks.net>
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