OpenBSC October 2018

openbsc@lists.osmocom.org

28 participants
37 discussions

Status of external USSD applications?
by Michael Benedict 23 Oct '18

23 Oct '18

Hi all, This is my second email here so I will start with a quick introduction before a question: I’m part of of an early stage company called Hover (www.usehover.com). We offer an Android software development kit written in Java that helps smartphone app developers automate USSD sessions in the background of native apps. A typical use case is to build a nicer user interface for, eg. mobile money transfers or airtime top-up. Colleagues at the University of Washington pointed me to this exciting project, and I have a B210 set up so I can register a phone on an Osmocom network and run *#100# to see my MSISDN from OsmoHLR. Which brings me to my question: I see that Rowan Phipps at UW has modified an earlier version of the Osmocom stack to run arbitrary USSD sessions from a Python web server. It looks like related work was started in 9658 and 9661 [1], [2]. Are these commits working, and what would be the best way for me to contribute to or test this work? I would prefer to run the newer Osmo* projects rather than try to use OsmoNITB. I am in the process of reading Rowan and Fairwaves' work and will happily share anything I learn. As context, we have 50k+ USSD session logs (i.e. menu text, not Wireshark traces) from various markets. My end goal is to be able to test new apps against these logs and otherwise experiment with arbitrary USSD sessions locally. Thank you for any suggestions you can offer. —Michael [1] https://gerrit.osmocom.org/#/c/osmo-msc/+/9658/ [2] https://gerrit.osmocom.org/#/c/osmo-msc/+/9661/

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Network interconnection over VPN/SIP
by naif8 23 Oct '18

23 Oct '18

Hello everybody, I hope I'm in the right place here, for my question, if not please ignore or maybe point me to a better place. For start, I'm quit new to the whole GSM stack and still in the process of understanding it, so please if you have the feeling I maybe misunderstood something horrible, I probably have! Feel free to point that out :D. I working together with other peoble on a project witch aims to connect refugee camps in the middle east, to enable easy, safer and non profit communication between them, this is often a big need for example to find relatives, but also to communicate with in the camps because sometimes they are huge etc.. One part (an at the moment my part) of this is to build up independent GSM Networks per camp witch are interconnected with the other camps. The idea is to build GSM networks with in the camp witch are autonomous. If there is power they run, if there is internet peoble can call the other camps (if they have internet). Every thing need's to be done without any central entity (like an HLR for all camps, run on a Server in Frankfurt) so that when, let say government xy decides to only allow nation wide networking an cut's the internet (happened since I'm here 2 times, it's annoying as f**k), the camp's within the country and in the camp it self can still communicate. The question is how to do this interconnection? As fare as I understand in classical GSM infrastructure, this is done by SS7, but since we are not interested (at least by know) to interconnect with "big" providers, and also I did not found an open source implementation (but maybe I missed it) this seems not an option, so the plan now is to do this over VPN's and SIP/VOIP Server (probably asterisk). We like to be able to scale the camps number, and to be relative easy to maintain so we can enable people to run this them self (after we learned to run this our self of course ;)). And these protocols are fare better documented then SS7 so also much more esay to learn and to debug. We are still testing and researching and so I thought it is maybe a good time to ask her if this is a valid way or I missing something, or maybe you can point me towards some documentations where people did some similar things. We are all not professionals and do this more or less with learning by doing, but we don't need to do all the mistakes other did before us :D (maybe some but not all) thx in advance and for this great project witch enabled us to do stuff like this naif

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help need with the silent_call function in OsmoMSC/BSC
by Mihai Ordean 23 Oct '18

23 Oct '18

Hey, I am trying to set up test bench for base-band fuzzing using the Osmocom stack and a couple of SDRs (b210 and bladerf). I have managed to setup everything to my liking in terms of a functional network using the tutorial (https://osmocom.org/projects/cellular-infrastructure/wiki/Osmocom_Network_I…) and the latest stable packages from https://osmocom.org/projects/cellular-infrastructure/wiki/Latest_Builds Now I want to enable the silent_call functionality to begin testing but I can't seem able to do so. I have reverted the silent_call patch (https://gerrit.osmocom.org/#/c/openbsc/+/1930/) for OpenBSC inside the "new" OsmoMSC but unfortunately that did not work. I have then started trying to figure out how the silent_call interacts with the rest of the state machine, but I don't seem to be making much progress. Please see attached a log for the communication between OsmoMSC (which triggers silent_call) and OsmoBSC. The connection seems to fail due to issues related to either "Congestion" (if GPRS is enabled) or a timeout of T0 (if GPRS is disabled). Can anyone help? Thanks -- Mihai

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Save the Date: OsmoCon 2018 on October 18-19, 2018
by Harald Welte 19 Oct '18

19 Oct '18

== OsmoCon 2018 == OsmoCon (Osmocom Conference) 2018 is the technical conference for Osmocom users, operators and developers! We are happy to announce the date of OsmoCon 2018. It has been scheduled on October 18 + 19, 2018 and will happen in Berlin, Germany. For the second time, the Osmocom Conference brings together users, operators and developers of the Osmocom Open Source cellular infrastructure projects, such as OsmoBTS, OsmoBSC, OsmoSGSN, OpenGGSN and others. Join us for two days of presentations and discussions with the main developers behind Open Source Mobile Communications, as well as commercial and non-profit users of the Osmocom cellular infrastructure software. You can find some initial information in our wiki at http://osmocom.org/projects/osmo-dev-con/wiki/OsmoCon2018 which will be updated as more information becomes available. == Call for Participation == We're also at the same time announcing the Call for Participation and call on everyone with experiences to share around the Osmocom member projects to submit talks, workshops, discussions or other proposals. You can find the CfP at https://pretalx.sysmocom.de/osmocon2018/cfp We are particularly looking for contributions about: * updates on features/functionality/status of individual Osmocom projects * success stories on how Osmocom projects are deployed in practice * migration from OsmoNITB to the post-NITB architecture * tutorials / workshops on how to setup / analyze Osmocom projects * statistics, reporting, operations aspects of Osmocom projects * third-party open source utilities to be used with Osmocom projects Looking forward to meeting many existing and new Osmocom users at OsmCon this October! Regards, Harald Welte -- - 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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BS-11 Firmware
by Andrew Voce 17 Oct '18

17 Oct '18

Hi, I'm wondering where I can source the Siemens BS11 firmware. It looks like OpenBSC is not providing any firmware images. # bs11_config -p /dev/ttyUSB0 bs11_config (C) 2009-2010 by Harald Welte and Dieter Spaar This is FREE SOFTWARE with ABSOLUTELY NO WARRANTY LMT LOGON: ACK PHASE: 1 Software required Abis-link: Down No valid Safety Load file "BTSBMC76.SWI" Thanks, Andrew

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Location Updating failure due to Speech Codec
by Neels Hofmeyr 17 Oct '18

17 Oct '18

Recently, dexter has added this commit: http://git.osmocom.org/osmo-bsc/commit/?id=b9d3c71af347906cef2bb54be57418a9… Our osmo-gsm-tester tests fail to pass since this commit thwarts all L3 Complete. The commit refuses to compose a Layer-3-Complete message if the speech codecs supported by the BSS cannot be included, either because none are configured, or because none remain after all the criteria of finding codecs permitted. It may be mandatory to include the speech codecs or not, what bugs me is that we even refuse a mere attach to the network just because speech codecs are not available. Those only become interesting much much later, only for voice. The backwards-compatibility consideration: configurations that have always worked well are suddenly likely to fail. Users will wonder what happened, and we need to avoid that. I think instead of thwarting L3 Complete entirely, we should loudly error-log, but still send out an L3 Complete while simply omitting the speech codec list. It might be a spec violation for AoIP, but practically works fine, AFAICT. Again, the way to handle this spec violation should be to log an error, not to break all access. The alternative would be, IMHO, to abort osmo-bsc startup right away, complaining about misconfiguration, if that is possible at all. But no. Let's allow L3 Complete even in the absence of speech codecs that all participants support. There are USSD and SMS and GPRS that are all going to be broken just because codecs don't match. The commit right after sets, apparently, the full list of codecs as supported by default. Is that not working? Do we override that in the osmo-gsm-tester config? Either way, even if the allowed codecs are all configured properly, but there is simply no match between MS,BTS,BSC,MSC, we would still refuse LU, right? Hence I would like to revert above commit / replace with error logging. @dexter, what do you think? Am I making sense, or am I missing something? Thanks! ~N P.S.: in that commit log, it would have been nice to mention the config items that would help solve the situation. It's not entirely clear to me yet what the misconfigured items are on the osmo-gsm-tester setup.

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BSC / MSC volatile state / restart handling
by Keith 16 Oct '18

16 Oct '18

Hi All. This is very brief, but something that's been on my mind to make a ticket about. I realise maybe it's better to ask first if there is a plan. The issue is about restarting MSC or BSC (or both). I still really haven't looked at the split setup enough yet, in terms of getting familiar with all the info available from logging in both programs, so I don't have a good analysis of what's going on. Sorry. But my point here is not to describe a bug to be fixed but just asking in general what is the strategy to deal with daemon restarts, intentional or not. Is there a plan to implement some kind of non-volatile state? The problem in terms of usability, from simple observation: In the case of restarting the MSC with two phones connected, of course the phones don't notice anything. One now needs to attempt a call setup at least 3 times, including a call setup attempt from the "callee" phone before we can even call it. I tried restarting both BSC and MSC, in various orders, and I did not get a satisfactory result. Of course, restarting the BSC restarts osmo-bts which causes (some) phones to notice the temporary loss of BCCH, but of course no LUR or anything as LAC doesn't change, so there's some state that is not getting set right someplace on restart, as I said. both phones need to interact before one of them can be called. Yeah, so, sorry for the lame analysis, but I think this should be pretty easy to reproduce, and at this time there are people who are MUCH more familiar with osmo-msc and osmo-bsc than me, who probably know what I'm talking about and can comment. Thanks! k/

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SS requests do bad things.
by Keith 12 Oct '18

12 Oct '18

Hi all Another one not quite ready for a ticket, but maybe worth mentioning here. A while back I noticed a phone of mine was holding channels open all the time. Turns out in does checks for call forwarding status and such on camping. This got fixed in Legacy OpenBSC: https://gerrit.osmocom.org/#/c/openbsc/+/503/ I noticed this, or something similar is back with the split setup. Try dialing *#21# for example. or pick a code from here: http://www.geckobeach.com/cellular/secrets/gsmcodes.php Then make a call. On some phones you can't, but if it does proceed, then hangup. On all the phones I tried you now have not only a lingering SDCCH, but also a TCH/F and on one phone, it doesn't ever go away, until you turn off the phone, or drop the BCCH. sorry again for the lame bug report. I don't want to forget it and I can't pay it due attention in the coming days. k/

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IuUP, aka voice between 2G and 3G
by Neels Hofmeyr 11 Oct '18

11 Oct '18

[private hacking hat on] Thinking ahead to the 35C3, I have tinkered with IuUP a bit. I'm at the point where I have an IuUP core net node in the osmo-mgw, which auto-detects IuUP peers and removes IuUP headers coming from a 3G RNC, and inserts IuUP headers in RTP going to a 3G RNC. So far we were merely hacking over the IuUP header to mimick an Initialization ACK, and were otherwise just handing the IuUP headers through from one 3G peer to the other. I realized now that hacking up an Initialization ACK like we currently do on osmo-mgw master produces a header CRC error, which the femto cells we currently tested completely don't care about, thankfully. Ok, so now I am de/encapsulating the IuUP from/to RTP, so that IuUP is present only on the last leg to/from an RNC. 3G to 3G calls still work well with that, now also having correct IuUP header CRCs. And, the naive idea was that now the 2G would simply understand the RTP from the 3G and vice versa. But that's not the case, apparently. The phones at best crackle some random artifacts. I picked a codec-list of fr3 hr3 in osmo-bsc, and tried a few AMR rates (12.2k, 5.9k, 5.2k). So I think there's still some fundamental concept that I'm lacking. Is there anyone more familiar with AMR and/or the way 3G encodes audio, and whether there's a simple way to make them match? Where should I read on? Would a call router like we use in the C3 POC be able to transcode when the IuUP is stripped? (I'm not even sure what the POC side is doing to connect SIP with GSM.) I've noticed the laforge/iu_up branch in libosmocore only later, which includes an FSM that apparently does only state transitions so far. My patch has no FSM yet, since all I see on the wire is Init->InitAck, then Data PDUs, and maybe an occasional error report. Do those FSM states convey a secret of making 3G encoding readable by 2G? Various pcaps of the status quo are here: http://kleinekatze.de/eeD0ouCo/ My IuUP branch: osmo-mgw neels/iuup http://git.osmocom.org/osmo-mgw/log/?h=neels/iuup IuUP protocol spec: 3GPP TS 25.415 (I've so far ignored most of it) ~N

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Persistent VTY history?
by Keith 11 Oct '18

11 Oct '18

Hi all. Was just thinking today about if it was ever considered to write the VTY history out to a file on exiting (and load it on startup) I'm quite the fan of the up arrow and it's been something that sometimes annoys that I have no history after leaving the VTY. It would seem reasonably trivial to implement, and I suppose you could write out to files in $HOME/.osmo-bsc_history or $HOME/.config or somesuch. Just wondering if this was ever discussed before, if there's any unforseen problem with it on my part + if it would be a desirable feature for anybody else? k/

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OpenBSC October 2018