OpenBSC August 2010

openbsc@lists.osmocom.org

21 participants
25 discussions

Several questions
by jason mercury 06 Dec '12

06 Dec '12

I have some questions: 1) When I start bsc_hack bsc_init.c first establishes OML link and initializes the bts then it establishes RSL link and bts starts broadcasting. However, it takes so much time to start the bts. Instead of this I want to do the following: it establishes OML link at the beginning and only once, then when i want to start broadcasting it establishes just the RSL link and bts will start faster since i don't have to wait for OML link. What should be done for this? 2) If i send one or two word messages from telnet interface it is okay. But if i send a longer message the phone could't receive the end of the message correctly(last words may be incomplete). Did any one encounter with this problem? What is wrong with me? 3) Could I send SMS in which extension of the sender is text not integer. For example, i want to send an information SMS that this is a test network. For this purpose i want to send an SMS from 'OpenBSC'. I set the extension of the first subscriber in database as text and tried to send the SMS but SMS wasn't delivered. What should i do? 4) Can i add SMS externally to SMS table of database? Thanks. Jason

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New utility for drawing protocol ladder diagrams
by Harald Welte 21 Feb '11

21 Feb '11

Hi! With the help of graphviz, I have written a small perl-based tool that allows you to generate ladder diagrams. It can be found at git://git.osmocom.org/gen_ladder.git For your reference, I'm attaching a sample input and output file. The bent/curved arrows are a result of graphviz trying to indicate that the message is between e.g. MS and MSC and 'bypasses' BTS and BSC. I'm still waiting for somebody with more graphviz skills to make this an option. Hope this is useful for some of you... -- - Harald Welte <laforge(a)gnumonks.org> http://laforge.gnumonks.org/ ============================================================================ "Privacy in residential applications is a desirable marketing option." (ETSI EN 300 175-7 Ch. A6)

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Proposed OpenBSC application interface
by Harald Welte 15 Feb '11

15 Feb '11

Hi! Collin Mulliner, Tobias Engel and myself have been meeting yesterday to discuss a generic application interface for OpenBSC. They are both doing security analysis and want to achieve a clean way how an external application can get access to a more or less transparent communication channel to the phone. The purpose of this is to be able to send intentionally malformed packets to the mobile phone GSM stack at various different levels within the stack. As of now, they have both hacked some custom code into openbsc that gets them half way where they want to be - but not quite all the way. The requirements can be summarized as follows: 1) Ability to establish a SDCCH or TCH channel by paging the phone As of now, the 'silent call' feature from the VTY already does this. 2) Ability to send arbitrary layer3 protocol messages to the phone Adding this is relatively easy (use rsl_sendmsg on the lchan from the silent call) 3) Ability to receive responses from the phone, as well as error conditions such as 'readio link failure'. We don't have a solution for this yet, and we also have no clean way to identify what might be a response from the phone to the external app, and what might be a message from the phone to the normal network code in OpenBSC 4) Ability to selectively disable partial protocol handling in OpenBSC. Let's say you want to play with the mobile phone call control implementation. In this case, you want to make sure all CC related messages go from/to the external program and not from the regular OpenBSC network code. So what I've been thinking of as a solution to the problem: * store a bypass_flags bitmask related to the subscriber structure, where we indicate values such as BYPASS_RR, BYPASS_MM, BYPASS_CC, BYPASS_SAPI3. * if we process an incoming message from the MS in gsm0408_rcvmsg(), we check if a bypass flag matching the message is found. If yes, forward the message to the external program * if we want to send a message from our own protocol stack to the MS, we check if a bypass flag matching the message is found. If yes, we drop the message that we were about to send. * any messages received from the application will be forwarded to the MS The application interface protocol will likely have a close resemblance to RSL RLL. We need to exchange the following primitives with the application, like: * ESTABLISH REQUEST -- app requests a channel be established to MS (by IMSI) * ESTABLISH CONFIRM -- network confirms a channel has been established * ESTABLISH INDICATION -- network tells app connection was made by MS * [UNIT] DATA REQUEST -- app requests data to be sent to MS * [UNIT] DATA INDICATION -- network indicates data was received from MS * ERROR INDICATION -- network tells app something went wrong * RELEASE REQUEST -- app asks network to release channel * RELEASE CONFIRM -- net tells app that channel was released (as rqd) * RELEASE INDICATION -- net tells app that channel was released (by MS) The channel_number of RSL (indicating on-air timeslot) doesn't make much sense in this context, of course. The link_identifier on the other hand is great as it allows the app to indicate SDCCH/FACCH or SACCH as well as the SAPI. The actual RSL-like protocol would be encapsulated by UDP and available on a socket of the MSC. What do you think? Regards, Harald -- - Harald Welte <laforge(a)gnumonks.org> http://laforge.gnumonks.org/ ============================================================================ "Privacy in residential applications is a desirable marketing option." (ETSI EN 300 175-7 Ch. A6)

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RFC: Relicensing OpenBSC under AGPLv3
by Harald Welte 01 Jan '11

01 Jan '11

Hi all! This subject came to my attention again recently: Why not relicense OpenBSC under AGPLv3? Right now we are licensing under GPLv2+ (v2 or any later version). However, if an operator was to make lots of private modifications and then operate it on his own network, there would be no distribution and thus no need for him to release his modified versions of the source code. This may sound a bit strange to those who have been with the project since its early days. But we are reaching production quality now, and we already have the first number of production deployments of the software. Companies like Netzing and On-waves have been FOSS-friendly and funding parts of our development effort. They have no issues with the result being Free Software again. However, there are definitely other companies out there who are less fond of sharing... So thus my idea is to put OpenBSC under AGPLv3. This way whoever uses OpenBSC _in modified form_ to operate a communications network will have to provide the source code to that modified form on a network server at no charge. The only controversial question to me is "your modified version must prominently offer all users interacting with it remotely through a computer network (if your version supports such interaction) an opportunity to receive the Corresponding Source". 1) does a gsm network count as computer network? i'd say yes. 2) is using a gsm network 'interacting with it remotely'? I'd also say yes 3) what does 'prominently offer' mean in the context of GSM? We don't want the operator to spam their users with advertisement SMS just to know that they can get the soruce code, after all. Notwithstanding those open questions, such a network operator would always have the option of simply sending back his changes for integration in the official project - and thus he would no longer use a modified version which then means there is no need for the prominent notice / download at all. We can make this very clear in the project documentation, putting further encouragement The actual relicensing should be less problematic than I thought, since AGPLv3 is compatible with GPLv3. So I could re-license all parts that I own copyright on (which should be the majority of the code base anyway) under AGPLv3, while the former GPLv2+ components (like VTY code from zebra, or contributions by other people) then become GPLv3-or-later. Of course I would want to encourage all developers/contributors to also follow the re-licensing. Particularly Holger Freyther, Dieter Spaar, Andreas Eversberg, Jan Luebbe, Sylvain Munaut, Daniel Willmann, Stefan Schmidt. So let's start with a poll: a) Do you think re-licensing to AGPLv3 is a good idea? b) If you have contributed, would you re-license your code under AGPLv3? If we have some kind of concesus in the community, I would approach On-waves whether they would want to do the same for their share of the copyright. As their "modifications" are all part of OpenBSC git repository, they would not be subject to any different conditions than before. Thanks in advance for your feedback, Harald -- - Harald Welte <laforge(a)gnumonks.org> http://laforge.gnumonks.org/ ============================================================================ "Privacy in residential applications is a desirable marketing option." (ETSI EN 300 175-7 Ch. A6)

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[PATCH 0/1] Add bport0/1 support for bs11_config
by Daniel Willmann 14 Dec '10

14 Dec '10

Hello, second try to add support to bs11_config for bport0/1 configuration. This time with enum abis_bs11_line_cfg. It seems sometimes creating bport1 fails, even LMT shows create obj greyed out. Don't know why yet. Regards, Daniel Willmann Daniel Willmann (1): Add {create,delete}-bport1 and bport0-{star,multidrop} to bs11-config openbsc/include/openbsc/abis_nm.h | 10 +++++++++- openbsc/src/abis_nm.c | 31 +++++++++++++++++++++++++++++-- openbsc/src/bs11_config.c | 26 ++++++++++++++++++++++++++ 3 files changed, 64 insertions(+), 3 deletions(-)

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Re: Problem connecting to NanoBTS with current version of OpenBSC
by Dieter Spaar 07 Sep '10

07 Sep '10

Hello Andreas, On Sun, 22 Aug 2010 21:03:46 +0200, "Andreas Schmidt-Dannert" <aschmida(a)mail.tu-berlin.de> wrote: > > I am playing around with RRLP and since newer versions of OpenBSC also > support packet data I wanted to upgrade to be able to receive A-GPS > data from the internet. I don't know whats wrong with your configuration, I can just say that here switching between different PCs running OpenBSC works without problems when the correct OML IP address has been configured for the nanoBTS ("-o" option of "ipaccess-config") and the nanoBTS was restarted. I am interested in what you want do try with RRLP because I recently did some more experiments with it. Especially I would like to try "MS-assisted" position measurements next, however this method requires the acquisition assitance data which have to be calculated first, I don't think they can be extracted from the data of a GPS receiver. I don't know if there is some ready and tested code for this already available which would make it easier to get this up an running. Best regards, Dieter -- Dieter Spaar, Germany spaar(a)mirider.augusta.de

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Latest OpenBSC version that is working with the rugby nanoBTS?
by Holger Hans Peter Freyther 01 Sep '10

01 Sep '10

Hi, is anyone still using the rugby sized nanoBTS? What is the latest version of OpenBSC that is working for you?

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SCCP protocol
by mosbah abdelkader 25 Aug '10

25 Aug '10

Is the SCCP protocol implementation complete in the OpenBSC project? And, what is the protocol used under it (MTP3?)?

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RRLP [was: Problem connecting to NanoBTS with current version of OpenBSC]
by Dieter Spaar 23 Aug '10

23 Aug '10

Hello Andreas, On Sun, 22 Aug 2010 23:35:17 +0200, "Andreas Schmidt-Dannert" <aschmida(a)mail.tu-berlin.de> wrote: > > So bringing ms-assisted positioning to work is also a goal of me. > Is it not possible to just transfer the acquired data from the GPS > receiver in the MS to a A-GPS server in the network and let te server > compute the acquisition assistance data? Probably I am thinking to naive > here. I know it should be a server not too far away from the asking MS. My experience with two phones (BlackBerry, HTC with Qualcomm chipset) is that if the phone already has the position (for example because a GPS application is running on the phone) the phone will return the position without asking for assitance data. However if there is no position, they usually want the reference time, reference location and navigation model (ephemeris) as assitance data. One problem with this approach it that the size of those data are quite large (around 800 bytes in my tests) if they have to be transferred over a slow channel like the SDCCH during loacation update, so this slows done the location update considerable. Another problem which is most certainly related to the bad GSM receiver in my test phones is that it take very long to get a fix, even with the provided assitance data. In my experiments this was around 45 second, nearly the same time as getting a fix without any RRLP data. Of course there could be a problem with the assitance data so that getting a position takes that long. So I would like to try MS-assisted measurement where only a small amount of data has to be transferred to the phone. I don't know if the measurement will also be faster this way. I did not try it yet because the acquisition assitance data have to be calculated, for example you need the doppler shift of the satellite signal which has to be calculated from the satellite postition. Probably no "black magic" but I would prefer to have ready and tested code to avoid another source of possible errors (its a matter of time, I don't want to spent too much on it ;-). > By the way there was for a while a rrlp-ephemeris tree in openbsc. What > was it for and what happend with it? As i understood it one could > connect an external GPS device to a laptop to get data that is > needed..kind of an A-GPS server. Right? I don't know where the tree is now. Its from Sylvain, maybe he can tell you more. I used this code as a basis for my experiments. > Another tought: What about SUPL? > SUPL uses IP to get assistance data from a SUPL server...so maybe it is > possible to use a supl server from google or similar? I don't have much experience with it. I guess that you can get the other assitance data (e.g. ephemeris) this way. But I am not sure about the acquisition assitance data. Best regards, Dieter -- Dieter Spaar, Germany spaar(a)mirider.augusta.de

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Problem connecting to NanoBTS with current version of OpenBSC
by Andreas Schmidt-Dannert 22 Aug '10

22 Aug '10

Hello all, till last Friday I was using a version of OpenBSC from around May. I used it on a machine with Fedora 13 and I had no problems at all. I am playing around with RRLP and since newer versions of OpenBSC also support packet data I wanted to upgrade to be able to receive A-GPS data from the internet. Anyway I am having problems getting it to work. Since Friday I am trying but without success and now I am really clueless and hope I will find some help here. First I installed it on a machine with Kubuntu 10.04 and I did the installation as recommended online for GPRS usage. The NanoBTS gets an IP adresse and I can configure it. After restart the led blinks slow and orange which means (after manual) the management link has not been establish. The slow blinking also occurred when I used the older version and there it worked so I guess the blinking can be ignored. However if I start bsc_hack it stops after the following: DB: Database initialized DB: Database prepared (hlr.sqlite3 exists afterwards) The debugging option did not reveal more information. Wireshark tells me that after DHCP there are no more packets coming from the NanoBTS. So even when I start bsc_hack there is no packet being transfered from OpenBSC to the NanoBTS....very strange. I thought it has something to do with firewall rules (under Fedora I had this problem) but I disabled everything and nothing happened. Then I thought maybe the problem is that I have installed OpenGGSN already and can now only start it when OpenBSC, osmo-sgsn and ggsn is configured and so I used my second machine (Debian Lenny) and installed only OpenBSC but I have the same problem there....the NanoBTS just keeps blinking slowly and orange. I do not think it is aproblem with the NanoBTS since it was still working on Friday. I reseted the NanoBTS several times, I gave it always around 2 or more minutes to connect and start (after starting bsc_hack) but it does not change anything. I guess it is a small problem but I just cannot see it. Maybe someone has a hint for me? Why are there no packets being exchanged? Sorry for the long mail but I wanted to explain it as detailed as possible so that the experts have it easier :) Thanks and Bye, Andreas

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OpenBSC August 2010