The Internet - Intro Notes - Back to Index

BT Broadband


Dr Richard Clayton has called for BT to be prosecuted for illegally intercepting customers' web traffic and illegally processing their personal data.


There has been a lot of talk about an Internet advertising system called Phorm which BT, Virgin Media and Talk Talk are all planning to deploy. Unless these companies obtain proper informed consent from customers it seems like it would contravene RIPA laws in the UK. Now it turns out that BT did secret trials in 2006 and 2007 and it is alleged that these were in fact illegal. Strange that nobody seemed to make a fuss when BT did secret trials of their "Cleanfeed" system back in 2004.


I just got an email from my broadband supplier which said:

We have been informed by our ADSL supplier that BT will be introducing a charge of ?33.75+VAT for all ADSL lines cancelled from 1st May 2007. Unfortunately this leaves us with no choice but to pass this charge on to any customers who wish to cease their ADSL line after this date.

I am not happy about this and might have to have words with BT about it.


In my last entry I mentioned that BT had offered to auto-renew my registration with the Telephone Preference Service, telling me that registration normally expires after a year. According to the TPS FAQ that is not the case, and residential numbers are supposed to remain on the register indefinitely (or until they are de-registered).


I was just searching for some information about ADSL modems (I want to use my ADSL provider's native IPv6 capability but my Draytek router doesn't support IPv6 and neither do their newer models so I am thinking about chucking the router and connecting my Mac straight to the Internet through an ADSL modem - end of digression) when I stumbled upon an interesting page describing another BT Broadband customer support debacle. See Problems with BT Broadband (BT Suck!) at Y Safle.

Incidentally, on 2006-08-18 a Dr. Fernando used my contact form from a machine at the University of Birmingham to tell me about another similar situation:

I have just sent this letter to BT plc. We are almost physically unwell after having to deal with a broadband problem for about a month, talking to apx 50 DIFFERENT people all giving conflicting information. This is literally a form of torture, and I would like your advice. Please feel free to publish this letter.

I replied with my sympathies but didn't take her up on the offer to publish her letter because this was never intended to be "BT Sucks" page. As far as basic provision of a phone line is concerned I have no complaints about BT. I phoned customer support about a week ago to cancel my call barring service and the man on the line was most helpful and efficient. He even offered to activate caller display on my line and activate annual auto-registering of my number with the Telephone Preference Service. and as both services are free I agreed (I registered with TPS myself some time ago but had forgotten to renew). One more quick digression for today. Once I got a cold call that went like this:


Richard Clayton presented a paper titled "Failures in a Hybrid Content Blocking System" at a workshop in Dubrovnic in mid 2005. The paper was based on an examination of BT's CleanFeed system (officially called the BT Anti-Child-Abuse Initiative).

In an earlier entry on this page I suggested that a blocking system would be more acceptable if it told users when they were being blocked rather than pretending that the page does not exist. I now realise that one of the most important design goals of such a system is to avoid alerting the user to the fact that content has been blocked. If that goal is not achieved then the system could be used as an "oracle" to efficiently locate illegal content (which could then be retrieved using an anonymous proxy service residing outside the realm of control). Richard discovered weaknesses in the system which did in fact leave it open to an oracle attack.


Just to bring things up to date my ADSL connection was successfully migrated on 2004-10-29. My latest bill from BT indicated that they had charged me the full fee for the quarter ending 2004-12-31 but I queried it yesterday and they claimed that I would get a revised bill.


It looks like Black Cat Networks are still waiting for a commit date from BT for my pending ADSL migration.


Today I phoned a BT number, navigated a voice menu system, waited on hold for about 15 minutes, gave all my details to a human and told her I needed my Migration Authorisation Code, got transferred, waited on hold for another 15 minutes and gave all my details again to another human who finally gave me the code. I then sent an email to my shell account provider with my phone number, preferred username, reverse DNS entry and MAC. Within half an hour I had received a reply confirming my username and giving me a password and IP address.

So as soon as BT get their act together I will have a new ADSL provider. BT will still be providing my PPP connection but it will terminate in a rack at Black Cat Networks, who will give me a static IP address with my requested reverse DNS entry and route my IP packets properly rather than hijacking them like BT does with it's Cleanfeed system.


On returning from a recent climbing trip I found a letter from Lee Chambers of the BT Complaint Review Service in which he attempted to address my concerns about the Cleanfeed system. He started out by claiming that Cleanfeed will not cause latency - which I basically accept (the latency I experienced in June was probably caused by some other problem at BT). He went on to say that Cleanfeed is not a pilot, but is in place permanently and for the foreseeable future. That may be the case now, but it was a pilot when I first raised the issue (someone at BT described it as being in "soft release"). Finally, whilst Lee accepted that there are methods of getting round it, he implied that any system which makes accessing child pornography more difficult must be good.

This response still leaves me unsatisfied. What I really want to know is why BT decided to introduce Cleanfeed in such a sneaky way, with no press releases, and without notifying their broadband customers, or even their own technical support staff. This subterfuge apparently extends to the operation of the system too, as this BBC article claims that anyone trying to access a blocked URL would be presented with a misleading message reading "Website not found" (I can't test this because I don't know any URLs on the banned list).


Regulator Ofcom has laid out its plans for the future of broadband in the UK. These plans include pushing forward the process of Local Loop Unbundling (LLU).


In my last entry I said that I was about to write an email to Raj at the BT Chairman's Office, which I did. I got a reply on 2004-06-25 in which he said he had arranged for the matter to be looked into, and that I would receive a response shortly. Meanwhile I have not experienced any more occurrences of high latency on my ssh connection, but that in itself does not prove anything about whether or not the problems I had before were related to the piloting of Cleanfeed. I should also say that people more knowledgeable than myself have expressed doubts about any such relationship.

It has been pointed out that if Cleanfeed simply blocks access to certain IP addresses then it would most likely have been implemented by adding routing table entries for those addresses to divert any packets into a trap. This would probably not significantly increase the burden on BT routers since they would already be holding a huge number of entries anyway.

Then there is the question of whether BT would be able to extend Cleanfeed to cover other broadband providers running their own services over BT lines. You can make a distinction between these ISPs based on where their end of the PPP session terminates. For some it terminates in BT equipment, but for others the IP traffic stays encapsulated in PPP right through the BT network and emerges in the ISPs own server room. In the latter case it would be much more difficult for BT to interfere with your traffic.

So now I am thinking about changing my broadband provider (unless BT do something pretty dramatic to redeem themselves) and have got a couple of good options. If I wanted to change immediately I would consider Eclipse, but there is a better option for me that might be available soon - if you are smart you might even be able to work out what it is:-)

Finally, I have just been reading a thread on ukcrypto where the eminent Clive D.W. Feather posted an apparently authoritative description of the Cleanfeed system as long ago as 2004-06-08. I wish I had found this earlier because it answers a few of my questions. I now accept that my slow ssh connections were very unlikely to have been directly caused by the piloting of Cleanfeed. I still have a couple of concerns though, one of them being the underhanded way that BT snuck this system in. The other issue is the exact nature of the fake 404 which will be returned when requests are blocked. It should certainly indicate clearly where and why the request was blocked. The IWF should also include a publicly advertised test URL in their banned list so that users can determine whether or not they are being censored.


I phoned the complaints number at BT this afternoon and spoke to a woman who revealed a bit more information. She said that "Cleanfeed" is in "soft release" (I think that was the expression) but that they would not be testing it if there was any possibility of it having negative effects on customers! She said that BT is not legally obliged to tell it's customers about such schemes, but when I suggested that it might be a good idea to do so anyway, she bizarrely went further and implied that they were legally prevented from doing so on the orders of Ofcom. Curiouser and curiouser. She then suggested that I go higher up and contact the Chairman's Office which I did.

My details were taken by Rachael at the Chairman's Office switchboard and I was promised a call back, finally I seemed to be getting somewhere. An hour or two later I received a call from Raj, who listened to what I had to say and then asked me to write it down in an email. I am about to do that now, and will keep you all posted.


I am beginning to suspect that the two issues I have with my BT broadband service are linked - the sneaky introduction of new censorship technology, and periods of high latency on my outgoing ssh connection. It seems that "Cleanfeed" is a pilot project but that it is expected to go live by the end of June. During testing BT might well be switching the system on and off which could explain why my latency problem is intermittent.

I spent another half hour today speaking to a woman at BT broadband technical support. She did a ping test and my router responded quickly so she said my line must be OK. I explained that there was no problem with ICMP anyway, but she was out of her depth. Next I asked her about "Cleanfeed" and she said she had never heard of it. She went away and asked a colleague who did know about it, but claimed that it would not affect me unless I was trying to look at child pornography. The fscked up thing is that people are going to be reluctant to complain for fear of being branded a paedophile - but the fact is that if I had any desire to look at illegal websites I would use something like Guardster, bypassing the "Cleanfeed" system altogether.

There are two main areas of concern for me. One is that "Cleanfeed" is going to hit performance. If ICMP echo responses take less than 15ms then anything more than about 0.3s latency for an ssh connection is simply not good enough. But aside from any technical problems, if the user is unable to distinguish the situation where a URL does not exist and the one where it exists but has been censored, then the system is clearly unacceptable.

The technical support woman gave me a number for the BT complaints line which I will call first thing tomorrow morning (she said she was a bit angry that she had not been informed either). If I don't get a satisfactory response I will start thinking about alternatives, and I will strongly recommend against anyone else signing up for BT broadband until the situation is clarified.


I regularly ssh to a machine called smokey and for the last few days there have been times when latency on the connection has been unacceptably high; we are talking several hundred mili-seconds between hitting a key and seeing the echo. I am pretty sure that smokey itself is not to blame, and ping time is consistently under 15ms.

On the issue of BT blocking access to certain websites, I got a worthless response to the feedback I submitted on 2004-06-08 which did nothing to address any of the points I raised. On the plus side though I found an article by BBC technology analyst Bill Thomson who warns that BT's filtering plans set a dangerous precedent, so I took the opportunity to leave a comment.

Anyway, I have learned a bit more about this new BT censorship system, known internally as "Cleanfeed", which blocks HTTP requests for websites listed by the Internet Watch Foundation. If you want to learn more about it then try a Google search for cleanfeed+btinternet. I will of course be keeping my eye on the situation.


I read this BBC article which claims that BT intends to prevent customers from viewing certain websites. Although I don't look at the sort of websites which are likely to be blocked, I was not happy about the fact that I had not been informed by BT of this planned change in service. I made a couple of phone calls then submitted the following feedback:

I just read that BT's internet customers will be blocked from viewing websites blacklisted by the Internet Watch Foundation. I am a BT broadband customer, and this is the first I have heard of it. I spoke to two people at BT. The first knew nothing about it and the second (technical support at 0870 2404650) said he had read it on "The Register"! Surely BT broadband customers deserve to be informed of changes to their service. As the BBC article hints, this sort of blocking is technically difficult and can lead to performance degradation, false positives, false negatives etc. Please provide sufficient technical details for me to independently assess the possible impact of this change on my broadband connection.


I had never connected to the Internet from home before 2003, but my lodger was often connecting and tying up my phone line so I decided to act. I knew I would shortly be getting my own computer so I decided to get a broadband connection. The choice was to either pay someone from ntl: to dig up my front garden or use my BT line. People I knew with ntl: had said that it was generally OK but that if anything went wrong you could go crazy trying to get support. I decided to go the BT route, and to get broadband directly from them rather than another company operating over their line.

So on 2003-01-30 I logged in to the BT website and ordered broadband. The connection process is simple. All BT have to do is put a filter on your line at the exchange end with the low frequencies going into the normal phone exchange and the high frequencies piped into their ADSL rack. A similar filter at your end splits the signal between your phone and your ADSL modem. Except in my case, instead of getting a modem I ordered a Draytek 2600We wireless ADSL router from Broadband Buyer (it seems like a bad idea to connect a machine directly to broadband when routers are so cheap). Setup was pretty simple, BT use PPP over ATM with VCMux encapsulation and G.DMT modulation.

By 2003-02-13 things were up and running and my lodger had no problems getting a wireless Internet connection from his room. By the summer I had my own machine and we were both happily sharing the connection. Since then we have been generally happy with the service. Ian Gregory 2010