Oct 22 2016


As is our custom on a Saturday, this morning my wife and I went out to a local cafe for breakfast. We know the proprietress so I was chatting to her whilst paying for the meal. Part way through the chat, the cafe proprietress tore off the receipt from the POS terminal and removed my debit card and handed it back to me.

Me: “Hang on, I haven’t entered my PIN. Are you sure that has been paid?”
CP: “Yes, it says here it’s paid.”
Me: “I have NOT authorised that transaction. It cannot be paid.”
CP: “Oh, don’t worry, we accept “swipe to pay” it probably just authorised that as you put your card in the terminal.”
Me: “That cannot happen. That card is not “swipe to pay” enabled. And I haven’t authorised any payment yet.”
CP (looking at receipt): “It says here “Contactless Sale” and the payment has been authorised”.
Me: “Show me that receipt.”

Sure enough, the receipt showed a “Contactless Sale” for the amount of the breakfast, however, the card type shown, and the last four digits of the card quoted were not those of my debit card. But I did recognise the card type as one I hold in my wallet so I checked that. Sure enough, that card has the WiFi symbol on it and the last four digits matched that on the Cafe receipt. So the POS terminal had taken the payment from a card in my wallet and not the card I had actually inserted.

That should not happen. And the fact that it did worries the hell out of me.

At the time the payment was taken, my wallet holding the other card was in my left hand (I had just removed my debit card from it with my right hand because I am right handed). So I placed that wallet on the counter beside me so that I could pick up the POS terminal in my left hand allowing me push my debit card in with my right hand and then enter my PIN. Replaying that action afterwards I am absolutely certain that at no time was my wallet anywhere nearer than a foot or more away from the POS terminal. Moreover that terminal had a card inserted – my debit card – and it should have been waiting for my PIN authorisation. So what happened?

I don’t know. And as I said above, that worries me.

I have checked both Wikipedia for details of the standards used in passive NFC of the type used in contactless payment and the “Security FAQ” for contactless payments on the Smart Card Alliance site (warning, PDF). Both those references tell me what I thought I already knew – NFC is only supposed to work at ranges of up to 2-4 inches (or 10 cm). No way was my wallet ever anywhere near 10 cm from that POS terminal. The closest it could have been was at least a foot away.

If this can happen to me, then I am certain it must have happened to others. Possibly to others who have been charged for someone else’s transaction simply because their NFC enabled card happens to be within range of the POS in question. In such cases, neither the actual customer nor the unwitting person really charged for the transaction would be any the wiser at the time of the transaction. Nor would the retailer know or care because they have a receipt for a contactless sale.

I’ll bet there have been some interesting conversations between such unwitting payers and their banks when the payment was noticed and then disputed.

Meanwhile, I’m going to find out whether I can get a card without the NFC capability to replace the card I unwittingly used to pay for breakfast. No way do I want this to happen again.

Permanent link to this article: http://baldric.net/2016/10/22/nfc-nfw/

Oct 19 2016

variable substitution in lighttpd

I’ve been a lighty user for many years now, having junked apache when it became obviously overweight for my target devices (the slugs in particular). Trivia is, of course, powered by lighty as are all my other websites.

Lighty’s configuration file syntax is reasonably simple to understand, and is well documented on the Redmine wiki. The guys at Calomel.org have also put together quite a nice introduction to lighty. If you haven’t tried it, and find that apache is becoming too much of a resource hog for you, I’d recommend that you give lighty a run.

I use lighty’s access control mechanisms to prevent random bots and bad guys from reaching trivia’s administrative functions and I do this in much the same way as I limit access to my ssh and openvpn daemons – I restrict access to the fixed IP address assigned to my router by my ISP. So in the lighty virtual host configuration file I use the following construct:

$HTTP[“remoteip”] !~ “” {
$HTTP[“url”] =~ “^/wp-admin/” {
url.access-deny = (“”)

That says: if the remote IP address is not, then deny access to the wp-admin directory.

Now I have several virtual hosts running and I also protect several directories. I also use a similar construct to redirect all my own access to my websites to port 443 so that I can always be certain that my own connection is encrypted and my authentication credentials will be protected. This means, of course, that I have several entries of the form: “if this IP address, then take this action” dotted around my configuration files. Not good. A recent change of ISP meant that my IP address has changed and I needed to edit my configuration files or find myself locked out. The most important files to change were my iptables rules so that I could still get ssh access on all my VMs. This didn’t take long because I have all the important configuration details (ssh IP addresses and ports, openvpn port, DNS addresses etc.) defined at the head of the bash script. One change is all that is necessary and bash variable substitution takes care of the rest. But my lighty configuration files were a different matter and I had to check carefully to ensure that I didn’t miss an important change. That’s just daft. Surely lighty allows for variable assignment and substitution. And of course it does, I just hadn’t checked before now.

The syntax looks like this:

At the head of the configuration file make an entry of the form:

# set our fixed remote ip address used in access control

IP = “”

and then change the earlier configuration lines to:

$HTTP[“remoteip”] !~ IP {
$HTTP[“url”] =~ “^/wp-admin/” {
url.access-deny = (“”)

Simple, and I feel a complete idiot for not noticing this before.

Permanent link to this article: http://baldric.net/2016/10/19/variable-substitution-in-lighttpd/

Jul 13 2016

show me yours

As Theresa May moves from the Home Office to Number 10, it is perhaps timely to reflect on public attitudes to surveillance as evidenced in Liberty’s campaign film “Show me yours” in April of this year. In the film (shown below), comedian Olivia Lee pursues members of the public with the intention of taking details from their mobile phones of all their recent communications or browsing activity. The reactions of the people approached speak for themselves. Unfortunately, Liberty research suggests that 75% of adults in the UK had never heard of the impending legislation laid out in the Investigatory Powers Bill.

Permanent link to this article: http://baldric.net/2016/07/13/show-me-yours/

May 02 2016

raid performance

I have recently been building a new NAS box (of which, possibly, more later). In fact the build is really a rebuild because I initially built the server about three years ago in order to consolidate a bunch of services I was running on assorted separate servers into one place. That first build was a RAID 1 array of two 2 TB disks (to give me a mirrored setup with a total of 2 TB store). At the time that was sufficient to hold all my important data (backed up both to other networked devices and to standalone USB disks for safety). But I have just upgraded my main desktop machine to a nice shiny new core i7 Skylake box with 16 GB of DDR4 and a 3 TB disk. That disk is already two thirds full (my old machine had a rather full 2 TB disk). This meant that my NAS backup storage requirements exceeded the capacity of my RAID 1 setup. Adding disks wouldn’t help of course because all that would do is add mirror capability rather than capacity. So I decided to upgrade the NAS and bought a bunch of new 2 TB disks with the intention of setting up a RAID 5 array of 4 disks, thus giving a total storage capacity of 6 TB (8 TB minus 2 TB for parity). Furthermore I initially looked at using FreeNAS rather than my usual debian or ubuntu server with software RAID simply because it looked interesting and, with plugins, could probably meet most of my requirements. But I could not get the software to install properly and after three abortive attempts I gave up and decided that I didn’t really like freeBSD anyway….

So I opted to go back to mdadm on linux – at least I know that works. Better still I would be able to retain all my old setup from the old RAID 1 system without having to worry about finding plugins to handle my media streaming requirements, or owncloud installation, for example.

My previous build was on debian (which is by far my preferred server OS) but ubuntu server has recently been released in a LTS version at 16.04 and I thought it might be fun to try that instead. So I did. (For any readers who have not tried installing linux on a RAID system there are plenty of sites offering advice, but the official ubuntu pages are pretty good). During the build I hit what I initially thought was a snag because the installation seemed to get stuck at around the 83% level when it was apparently installing the linux kernel image and headers. Indeed I confess that on the first such installation I pulled the plug after about three hours of no apparent activity because I was beginning to think that there might be something wrong with my hardware (the earlier FreeNAS failures worried me). My on-line searches for assistance were initially not particularly helpful since none of the huge number of sites advising on software RAID installation bothered to mention that initial RAID 5 build (or rebuild) using large capacity disks takes a very long time because of the need to calculate the parity data. Incidentally, it is this parity data and its layout that gives RAID 5 its write performance penalty.

One useful outcome of my research about RAID 5 build times (which in my case eventually took just over 6 hours) was my discovery of the wintelguy’s site providing an on-line calculator (and much more besides) for RAID performance and capacity. There is even a very useful page allowing you to compare two separate configurations side by side – thoroughly recommended. More worrying, and thought provoking, is the reclaime.com calculator for RAID failure. That site suggests that the probability of successfully rebuilding a RAID 5 array of 4 * 2 TB disks after a failure is only 52.8%.

That is why you need to keep backups…….

Permanent link to this article: http://baldric.net/2016/05/02/raid-performance/

Mar 30 2016

jibber jabber

For some time mow I have been increasingly fed up with the poor service offered by SMS on my mobile phone. I’m not a hugely prolific sender of text messages, and those I do send are primarily aimed at my wife and kids, but when I do send them, I expect them to get there, on time and reliably. I also expect to be able to send and receive images (by MMS) because that is what I have paid for in my contract. Oh, and I would also like to do this securely, and in privacy.

Guess what? I can’t.

My wife and kids want me to use Facebook’s messenger because that is what they use and they are happy with it. I have signally failed to convince them /not/ to use that application, largely because they already have it installed and use it to send messages to everyone else they know. But then I have also failed to get my kids to understand my concerns about wider Facebook usage. (“There Dad goes again, off on one about Facebook.”).

So, what to do? Answer, set up my own XMPP server and use that. XMPP is an open standard, there are plenty of good FOSS XMPP servers about (jabberd, ejabberd, prosody etc.) and there are also plenty of reasonable looking XMPP clients for both android and linux (the OS’s I care about). And better yet, it is perfectly possible (and relatively easy) to set up the server to accept only TLS encrypted connections so that conversations take place in private. Many clients also now support OTR or OMEMO encryption so the conversations can be made completely secure through end-to-end encryption. Yes, I am aware that OTR is a bit of a kludge, but it is infinitely preferable to clear text SMS over the mobile network. And I like my privacy. Better yet, unlike GPG which I use for email, OTR also provides forward secrecy, so even if my keys should be compromised, my conversations won’t be.

And yes I also know that Facebook messenger itself offers “security and pivacy”, but it also used to be capable of interacting with the open XMPP standard before Zuckerberg made it proprietary a few years ago. And I just don’t trust Facebook. For anything.

So for some time now I have been using my own XMPP server alongside my mail server. It works just fine, and I have even convinced my wife and kids to use it when they converse with me.

I may now move away from using GPG to using OTR in preference. Anyone wishing to contact me can now do so at my XMPP address and may also encrypt messages to me using my OTR key. My fingerprints are published here.

Permanent link to this article: http://baldric.net/2016/03/30/jibber-jabber/

Jan 24 2016

guest network

Last month Troy Hunt posted an interesting comment on his blog about the problems around the etiquette of allowing guests onto your home wifi network. In his post, Hunt notes that guests can be deeply offended at being refused access. This is understandable. If they are guests in your home then they are probably close friends or family. Refusing access can make it seem that you don’t trust them. However, as Hunt goes on to point out, it is not the guests per se you need to worry about. Anyone on your network can cause problems – usually completely unintentionally. In my case I have the particular problem that my kids assume that they can use the network when they are here. Worse, they assume that they may access the network through their (google infested) smart phones. Now try as I might, there is no way I can monitor or control the way my kids (or their partners) set up their phones. Nor should I want to.

Hunt asks how others handle this problem. Like him I don’t much trust the separation offered by “guest” networks on wifi routers. In my case I decided long ago to split my network in two. I have an outer network which connects directly to my ISP and a second, inner network, which connects through another router to my outer network. Both networks use NAT and each uses an address range drawn from RFC1918. Furthermore, the routers are from different manufacturers so, hopefully, any vulnerability in one /may/ not be present in the other. My inner network has all my domestic devices, including my NAS, music and video streaming systems, DNS server etc. attached. These devices are mostly hard wired through a switch to the inner router. I only use wifi where it is not possible to hard wire, or where it would make no sense to do so. For example, my Sonos speakers and the app controlling them on my android tablet must use wifi. However, there is no reason why my kids, who insist on using Facebook, need to have access to my internal systems. So I run a separate wifi network on the outer router and they only have access to that. The only systems on the external screened network is one of my VPN endpoints (useful for when I am out and about and want to appear to be accessing the wider world from my home), and my old slug based webcam. My policy stance on the inner network is to consider the screened outer network as almost as hostile as the wider internet. This has the further advantage that bloody google doesn’t get notification of my internal wifi settings through my kids leaving “backup and restore” active on their android phones.

Permanent link to this article: http://baldric.net/2016/01/24/guest-network/

Jan 11 2016

sign this now

I am a paying member of both Amnesty International and the Open Rights Group. Both those organisations, along with many other Civil Rights organisations, technology companies and concerned individuals are signatories to an open letter to Governments across the world demanding that we retain the right to strong encryption in order to protect our privacy. That letter says:

  • Governments should not ban or otherwise limit user access to encryption in any form or otherwise prohibit the implementation or use of encryption by grade or type;
  • Governments should not mandate the design or implementation of “backdoors” or vulnerabilities into tools, technologies, or services;
  • Governments should not require that tools, technologies, or services are designed or developed to allow for third-party access to unencrypted data or encryption keys;
  • Governments should not seek to weaken or undermine encryption standards or intentionally influence the establishment of encryption standards except to promote a higher level of information security. No government should mandate insecure encryption algorithms, standards, tools, or technologies; and
  • Governments should not, either by private or public agreement, compel or pressure an entity to engage in activity that is inconsistent with the above tenets.

I’ve signed. You should too.

Permanent link to this article: http://baldric.net/2016/01/11/sign-this-now/

Jan 07 2016


Today’s Register has an article about the UK Internet Service Providers Association written evidence to the Parliamentary Joint Committee on the Draft Investigatory Powers Bill.

I don’t wish to comment on that evidence here, Adrian Kennard has already provided much useful comment on the failings of the Draft Bill. My purpose in this post to highlight the absurdity of the Parliamentary Committee’s request that the ISPA evidence be withdrawn from it’s Website. The Register article ends with this update:

ISPA contacted The Register after the publication of this story to inform us: “ISPA was requested to remove the written evidence it submitted to the Joint Committee on the Investigatory Powers Bill from the ISPA website by the Joint Committee. Their guidance states that submissions become the property of the Committee and should not be published elsewhere until the Committee has done so itself.”

As of now (14.30 on 7 January) that evidence is still on the ISPA Website. Even if removed, it will still, of course, be available from a huge range of sources such as search engine caches (apologies for the google reference, but it is the obvious one). Or you could get it here.

The point is, once such a document has been published electronically on the net, no-one, but no-one, can put the genie back in the bottle and unpublish it.

The officials supporting the Joint Parliamentary Committee should know that. And if they don’t then I would submit that they are not technically competent enough to be supporting the Committee.

Permanent link to this article: http://baldric.net/2016/01/07/idiotic/

Jan 01 2016

a bad way to end the year

Sadly, I read today that Ian Murdock, the “Ian” in Debian, died on Monday, 28 December 2015. He was only 42 years old. Various reports indicate that he had been distressed for some time before his death. The tweets reportedly from Murdock’s twitter account shortly before his death are very disturbing.

Murdock’s contribution to the FLOSS community was immense. The operating system he created with “Deb”, Debra Lynn, his then girlfriend, is the foundation upon which much of today’s internet infrastructure is built. Ubuntu, one of the most popular desktop linux distros, is itself built upon debian. This blog, and all of my web, mail and other servers is built upon debian. His legacy will endure.

Murdock left a wife and two young children. He died much, much, too young.

Permanent link to this article: http://baldric.net/2016/01/01/a-bad-way-to-end-the-year/

Dec 24 2015

merry christmas 2015

It’s trivia’s birthday again (9 years old today!), so I just have to post to wish my readers (both of you, you know who you are….) a Merry Christmas and a happy New Year. Much has happened over the last year or so which has distracted me from blogging (life gets in the way sometimes) but I feel my muse returning so I may write more in the new year. Meanwhile, take a look at Alan Woodward’s update to Scott Culp’s 2000 essay “10 Immutable Laws Of Security” which he posted on the BBC site. It is called
have yourself a merry cyber-safe Christmas.

santa with laptop

I’ll drink to that.

Permanent link to this article: http://baldric.net/2015/12/24/merry-christmas-2015/

Dec 08 2015

knees and other jerks

On sunday, the motherboard intially reported that, in the wake of the Paris atrocities of November 13th, the French Government was proposing to ban Tor and free WiFi. As it turns out, this is not strictly accurate. The report was later corrected – thus:

Correction: The initial headline and copy of this article suggested that the proposals to block Tor and control free wifi were already part of a proposed law. These are in fact points that the French police and gendarmes would like to see included in the bill, according to the document seen by Le Monde. The headline and copy have been updated to clarify this; we apologise for the error.

Nevertheless, the actual story is still worrying. Governments of all shades seem to react badly when they feel that they must be seen to “do something”. We, in the UK, have already seen how the desire to “do something” results in unfortunate over reaction and ill-thought proposals for legislation. So it is sad to see the French (for whom I have much admiration) apparently reacting to Paris by opting to clamp down on civil liberties. I’d like to think that the reality is not as bad as the initial report suggested though. Certainly the motherboard post now makes clear that:

French law enforcement wants to have (my emphasis) several powers added to a proposed law, including the move to forbid and block the use of the Tor anonymity network, according to an internal document from the Ministry of Interior seen by French newspaper Le Monde.

It continues:

French law enforcement wish to “Forbid free and shared wi-fi connections” during a state of emergency. This comes from a police opinion included in the document: the reason being that it is apparently difficult to track individuals who use public wi-fi networks.

Noting that China actively blocks connections to Tor, the article continues:

If the French really wanted to block Tor, they might have to consider a model similar to the Chinese regime’s. Naturally, that might be worrying for anyone that cares about free-speech, increasing surveillance, or, say, democracy.

Let’s just hope that sense prevails and Western democracies do not react to terrorism in a way which reduces the very freedoms we cherish so much.

Permanent link to this article: http://baldric.net/2015/12/08/knees-and-other-jerks/

Nov 28 2015

cameron meets corbyn


(With thanks to David Malki!)

Permanent link to this article: http://baldric.net/2015/11/28/cameron-meets-corbyn/

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