I jsut bought some really old data cables for my Nokia 3410 and I must tell you they suck really bad. Let me tell you a little bit about the background:<\/p>\n
I am currently really into everything that is security & GSM, therefore I thought it would be great to have a data cable which I can use with my old Nokia 3410 to enable the so called “Network Monitor” mode. In this mode the phone shows you a lot of useful information like the frequency it is using (ARFCN) or the current temporary ID of the SIM card (TMSI).
\nSo, as a normal user would do I went to my friend Google and asked him about this cable. He quickly showed me some results which were quite funny: some Hungarian webshops still have these cables in stock! I was quite happy because the price was really low and I thought it would be great to buy from a shop and not from some random person.<\/p>\n
So the cables came like two days later, and I tried to connect them to my phone. None of the cables seemed to fit. I was really angry, and thought about calling the shop telling them they are selling junk (which wouldn’t be surprising at all sadly) but then I found an archive website that shows you how to connect the cable properly.
\nThe secret is quite easy once you know it: you need to get rid of the nice soft protecting foam that is glued all around the pins of the cable (who would have thought…). After that I connected the phone to my computer and I was able to turn on the Network Monitor – yeah, let’s all be happy.<\/p>\n
But how is this related to poor quality Chinese cables?<\/p>\n
Let me finish the story:
\nAs time went on I wanted to get more information out of the phone and I already found the tool for this, naturally it is part of the Osmocom-family, it is called dct3-gsmtap. It can use the serial connection to your phone to actually capture GSM and SIM-card data and then forward it to Wireshark for later analysis. Sweet, just what I wanted to try out.
\nI installed it, tried to run it, and it says something like “no answer from the phone”. What the ****? I just communicated with the phone, and turned on the Network Monitor!<\/p>\n
So I went back to Google and tried to research this, and finally found the cause:
\nApparently for Nokia phones you can have 2 kind of cables, one is called MBUS (M2BUS) the other one is called FBUS. They differ in speed, baudrate and also capabilities. MBUS is an older simpler implementation of a serial line – it only uses GND and MBUS_PIN (data pin) to communicate. It is slow, and not really useful, that’s why Nokia decided to introduce FBUS which uses GND, RX_PIN and TX_PIN so it is a lot faster and more reliable serial connection.
\nGuess which connection is supported by pretty much all of the tools available. Yes, FBUS.
\nGuess what kind of cable do I have? Yes, MBUS. Sweet…<\/p>\n
But I didn’t stop there, I wanted to see, if there were truly only 2 pins connected in my cable, or what was going on (because the interface facing the phone actually has all 4 pins). It turned out, that I do have 4 pins connected, but if I trace the whole cable it turns out that one of the magic plastic boxes on the cable (you know those little plastic boxes that are \u00c2\u00a0on some cables for noise-cancelling or something like that) has all 4 cables coming in and only 2 cables going out.
\nSo, I have an awesome cable which has all of its capabilities limited because some retard thought ‘yeah, why don’t we cut these two wires right at the middle of the cable?’.<\/p>\n
<\/p>\n
Fortunately Google is still my friend and I found a random guy on the Internet who is Hungarian and has one perfectly fine FBUS cable for Nokia 3310\/3410 which he is willing to sell. Ironic.<\/p>\n","protected":false},"excerpt":{"rendered":"
I jsut bought some really old data cables for my Nokia 3410 and I must tell you they suck really bad. Let me tell you a little bit about the background: I am currently really into everything that is security & GSM, therefore I thought it would be great to have a data cable which […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_mi_skip_tracking":false},"categories":[3,6,1],"tags":[],"_links":{"self":[{"href":"https:\/\/domonkos.tomcsanyi.net\/index.php?rest_route=\/wp\/v2\/posts\/364"}],"collection":[{"href":"https:\/\/domonkos.tomcsanyi.net\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/domonkos.tomcsanyi.net\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/domonkos.tomcsanyi.net\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/domonkos.tomcsanyi.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=364"}],"version-history":[{"count":1,"href":"https:\/\/domonkos.tomcsanyi.net\/index.php?rest_route=\/wp\/v2\/posts\/364\/revisions"}],"predecessor-version":[{"id":365,"href":"https:\/\/domonkos.tomcsanyi.net\/index.php?rest_route=\/wp\/v2\/posts\/364\/revisions\/365"}],"wp:attachment":[{"href":"https:\/\/domonkos.tomcsanyi.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=364"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/domonkos.tomcsanyi.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=364"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/domonkos.tomcsanyi.net\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=364"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}