When first attempting to view the tor site, readers are faced with this:

Clicking on the blacked out section you are taken to a copy of the 18 January blog posting which says:

“The Tor Project doesn’t usually get involved with U.S. copyright debates. But SOPA and PIPA (the House’s “Stop Online Piracy Act” and the Senate’s “Protect-IP Act”) go beyond enforcement of copyright. These copyright bills would strain the infrastructure of the Internet, on which many free communications — anonymous or identified — depend. Originally, the bills proposed that so-called “rogue sites” should be blocked through the Internet’s Domain Name System (DNS). That would have broken DNSSEC security and shared U.S. censorship tactics with those of China’s “great firewall.”

Now, while we hear that DNS-blocking is off the table, the bills remain threatening to the network of intermediaries who carry online speech. Most critically to Tor, SOPA contained a provision forbidding “circumvention” of court-ordered blocking that was written broadly enough that it could apply to Tor — which helps its users to “circumvent” local-network censorship. Further, both bills broaden the reach of intermediary liability, to hold conduits and search engines liable for user-supplied infringement. The private rights of action and “safe harbors” could force or encourage providers to censor well beyond the current DMCA’s “notice and takedown” provision (of which Chilling Effects documents numerous burdens and abuses).”

Jimmy Wales, the founder of wikipedia has been a particularly vocal critic of the impending legislation. Today, english speaking users of wikipedia were greeted with the following page:

There is plenty of discussion about the effects of SOPA and PIPA on-line in the usual technical fora (see wired, for example) but as El Reg said about a week ago, the mainstream media in the US have been largely quiet about the implications of the Bills should they ever become law.

I wonder why.

My mail setup is postfix/dovecot with SASL authentication and TLS protecting the mail authentication exchange. My X509 certs are self generated (and so not signed by any CA). I pick up mail over IMAPS (when mobile) and POP3S (at home – for perverse reasons of history I like to actually download mail to my main desktop over POP3 and archive it to two separate NAS backups). I send via the standard SMTP port 25 but require authentication and protect the exchange with TLS.

My mail had been working fine ever since I set it up some years ago, but as I said, back in October my wife complained that she could no longer send email from her HTC mobile (we both use t-mobile as the network provider). She was at work at the time so away from my home network. Both our phones are setup to use use wifi for connectivity where it is available (as it is at home of course). When my wife complained I checked my phone and it could send and receive without problem. But when I switched wifi off, thus forcing the data connection though the mobile network, I got the same problem as my wife reported. On checking my mail server logs I read this:

postfix/smtpd[28089]: connect from unknown[149.254.186.120]
postfix/smtpd[28089]: warning: network_biopair_interop: error reading 11 bytes from the network: Connection reset by peer
postfix/smtpd[28089]: SSL_accept error from unknown[149.254.186.120]:-1
postfix/smtpd[28089]: lost connection after STARTTLS from unknown[149.254.186.120]
postfix/smtpd[28089]: disconnect from unknown[149.254.186.120]

(the ip address is one of t-mobile’s servers on their “TMUK-WBR-N2″ network)

Everything I could find about that sort of message suggested that the client was tearing down the connection because there was something wrong with the TLS handshake and it was not trusted. Checking earlier logs, I found that t-mobile’s address had apparently changed (to the address above) recently. So I assumed that some recent network change following the Orange/T-mobile merger had been badly managed and all would be well again as soon as the problem was spotted. Wrong. It persisted. So I had to investigate further. As part of my investigation of the error, I tried moving mail from port 25 to 587 (submission) because that sometimes gets around the problem of ISPs blocking, or otherwise interfering, with outbound connections from their networks to port 25, No deal. In fact it looked as if t-mobile were blocking all connections to port 587 (I assumed a whitelisting policy block, or again, a cockup).

So, the scenario was: mail works when connecting over wifi and using my domestic ISP’s network, but doesn’t when using t-mobile’s 3G network. Symptoms point to a lack of trust in the TLS handshake. Tentative conclusion? There is an SSL/TLS proxy somewhere in the mobile operator’s chain. That proxy sucessfully negotiates with our phones, but when it gets my self certified X509 cert from the server. it can’t authenticate it and decides that the connection is untrusted so tears it down. My server sees this as the client (my phone) tearing down the connection. [As it turns out, this conclusion was completely wrong, but hey].

I said in an email at the time to a friend whose advice I was seeking, “I suspect cockup rather than outright conspiracy, but if my telco is dumb enough to stick a MITM ssl proxy in my mail chain, they really ought to have thought about handling self signed certs a little better. Otherwise it sort of gives the game away.”

In response, he very sensibly suggested that I should run a sniffer on the server and check what was going on. At that time, I was busy doing something else so I didn’t. And because the problem was intermittent (and my wife stopped complaining) I never got around to properly investigating further. (I should explain that I rarely send mail from my mobile nowadays. I just read mail there and wait until I get home to a decent keyboard and can reply to whatever needs handling from there. My wife just gave up bothering to try).

I should have persisted because of course I wasn’t the only one to experience this problem.

Back in November, a member of the t-mobile discussion forum called “dpg” posted a message complaining that he could not connect to port 587 over t-mobile’s 3G network. In response, a member of the t-mobile forum team suggested that dpg might reconfigure his email so that it was relayed via t-mobile’s own SMTP server. Not unreasonably, dpg didn’t think this was an acceptable response – not least because he would then have to send his email in clear. He then posted again saying that “the TLS handshake fails when the mail client receives a TCP packet with the reset (RST) flag set.” (This is a bad thing (TM). Further, he posted again saying that he had set up his own mail server and repeated earlier tests so that he could see both ends of the connection. At the client side he posted mail from his laptop tethered to his phone which was connected to the t-mobile 3G network. By running sniffers at both ends of the connection he was able to prove to his own satisfaction that something in the t-mobile network was sending a RST and tearing down any connection when a STARTTLS was seen. Again, in a later post in response to one from another poster who apparently manages several mail servers and had been looking at the same issue for a client, dpg says:

“I must say I’m not too pleased to discover that T-Mobile may be snooping all traffic to check for SMTP messages. I have demonstrated that they may be doing this by running a SMTP server on a non-standard port and finding that they still sent TCP reset packets during TLS negotiation – so they must be examining all packets and not just those destined for TCP ports 25 and 587.

I’m also not that keen on T-Mobile spoofing/forging TCP resets. This is the sort of tactic resorted to by the Great Firewall of China (http://www.lightbluetouchpaper.org/2006/06/27/ignoring-the-great-firewall-of-china/) and also by Comcast back in 2007 (https://www.eff.org/wp/packet-forgery-isps-report-comcast-affair) until the US FCC told them to stop (http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-08-183A1.pdf).”

Then 9 days ago, dpg posted this message:

“I finally got to the bottom of this. I was contacted by T-Mobile technical support today and was told that they are now actively looking for and blocking any TLS-secured SMTP sessions. So, it is a deliberate policy after all, despite what the support staff have been saying on here, twitter and on 150. They told me it is something they have been rolling out over the last three months – which explains why it was intermittent and dependent on IP address and APN to begin with.

So, the only options for sending email over T-Mobile’s network are:
- unencrypted but authenticated SMTP (usually on port 25)
- SSL-encrypted SMTP (usually on port 465)
- unauthenticated and unencrypted email to smtp.t-email.co.uk

TLS-encrypted SMTP sessions are always blocked whether or not they are on the default port of 587.”

(As an aside, there is, of course, another alternative. You can ditch t-mobile as your provider and pick one which doesn’t use DPI to screw your connections. You pays your money….)

Following this, a new poster called “mickeyc” said this:

“I’ve been experiencing this exact same problem. I run my own mail server which has SSL on port 465 and also uses TLS on port 587. I used wireshark to confirm that the RST packets are being spoofed. This is the exact same technology used by “The Great Firewall of China”. I have two t-mobile sims. One is about a year old and doesn’t experience this problem (yet), one is a few weeks old and does.”

He went to say that he had also experienced problems with his OpenVPN connections and would be blogging about the problem (damned bloggers get everywhere) and sure enough, Mike Cardwell did so at grepular.com. That blog post is worth reading because it has an interesting set of comments and responses from Mike appended.

Mike’s post seems to have been picked up by a few others (El Reg has one, and as Mike himself has pointed out, boingboing.net has a particularly OTT post which seems to say that he is accusing t-mobile of something he clearly isn’t.

Finally, two days ago, dpg posted this:

“I’m pleased to report that T-Mobile is no longer blocking TLS-secured email on port 587. As a follow-up to an email exchange over the Christmas period I was contacted today to say that, contrary to what I had been told previously, it was never a deliberate policy to block TLS-secured outgoing email. There was a problem with some equipment after all, which was resolved yesterday.”

I tried again myself today. Initially, I got the same old symptoms (“lost connection after STARTTLS”) then I rebooted my ‘phone and lo and behold I could send email.

Like Mike, I tend to the cockup over conspiracy theory, it’s more likely for one thing. IANAL, but it seems to me that it would be in breach of RIPA part I, Unlawful Interception, for the telco to intercept my SMTP traffic in the way it seems to have been doing. That is not likely to be a deliberate act by a major UK mobile network provider.

But I’ll still keep an eye on things.

Having shut down and had the DNS round robin amended, I attended to finding some way of throttling my traffic so that I could live within my allowance whilst still providing a useful mirror. I scratched my head for a while before stumbling on the obvious, I should be throttling at application level. (Sometimes I find that I miss simple answers because I am looking for complicated ones).

I started out by assuming that I should be using tc and iptables mangling, or something like the userspace tool trickle, all of which looked horribly more complicated than the approach taken by tor (which allows you to simply set the acceptable bandwidth rate to some limit, plus set an accounting period maximum of some total transfer limit per day/week whatever). And of course it turns out that my webserver (lighttpd) allows something similar. Just set the server limit to some chosen max transfer rate and, if necessary, also impose a per IP max rate. The magic configuration file options are:

# limit server throughput to 300 kbytes/sec (~3000 kbits/sec)
server.kbytes-per-second = 300
# and limit individual connections to 50 kbytes (~500 kbits/sec)
connection.kbytes-per-second = 50

I tested this by pulling a copy of the tails iso from one of my other VMs which has a high bandwidth connection and got acceptable (and expected) results. So now I can go back on-line later this month safe in the knowledge that I’m not going to blow all my bandwidth in one week.

Firstly, X is not exactly a secure protocol, nor is it easy to filter at NAT firewalls, so the ability to tunnel it over ssh is hugely welcome. In fact, ssh can be used to tunnel practically any other protocol you care to name, so it should be your first port of call should you wish to connect to a remote system using an insecure protocol. (I use it to wrap rsync for example).

I don’t run X on my VMs (there is no need, they don’t run desktop software) and I had not previously seen the need to run X based graphical programs on those servers. However, a couple of days ago I thought it would be really useful to run etherape on one particular remote server so that I could watch the traffic patterns. Normally I use iptraf (which is ncurses based) when I want to monitor network traffic in real time, but etherape is pretty cool and gives a nice graphical view of your network connections. But it runs on an X based gui.

So. I changed the remote server’s sshd_config to enable X forwarding (“X11Forwarding no” becomes “X11Forwarding yes”) and restarted sshd. On my desktop I similarly changed my local ssh_config file to allow X forwarding (“ForwardX11 no” becomes “ForwardX11 yes”) to obviate the need to use the -X switch on the command line. I then installed etherape on the remote server and fired it up only to get the message “Error: no display specified”. Sure enough “echo $DISPLAY” showed nothing. But I had thought (and everything I had read confirmed) that ssh should take care of setting the appropriate display when X11 forwarding was set.

So I then tried setting a display manually (export DISPLAY=localhost:10.0 on the remote server) and then got the response “Error: cannot open display: localhost:10.0″. So, still no deal. I spent some time scratching my head (and reading man pages) and sent off a query to my local Linux User group in parallel asking for advice. They were gentle with me.

The first, and rapid, response, said:

On the server:

sudo apt-get install xauth

Then disconnect and reconnect the client.

Jobs a good un.

Thank you Brett.

So the moral is, make sure that you have X authorisation working properly on the remote system (check for the existence of $HOME/.Xauthority) if you experience the same symptoms I did.

His response deserves as wide an audience as my original post, so I am drawing attention to it here.

Thank you Luke for taking the time to comment.

Standalone IP cameras have come down in price quite remarkably over the past few years. It is now perfectly possible to get a camera for between £50.00 and £75.00, and this makes them attractive for anyone wanting to set up simple “home surveillance” systems. I bought one recently just to see what I could realistically do with such a beast. I chose the TP-Link TL-SC3130G,

which goes for around £60.00. I bought mine from amazon. I chose this particular camera because, on paper, it looked to have a good specification at a keen price point. According to the TP Link website, the camera’s highlights include:

• 54Mbps wireless connectivity brings flexible placement
• Bi-directional audio allows users to listen and talk remotely
• Excellent low light sensitivity ensures good video quality even in the dawn
• MPEG-4/MJPEG dual streams for simultaneous remote recording and local surveillance

plus an impressive list of protocol capabilities all in a reasonably compact and attractive hardware package.

When the camera arrived I was pleased to find that the hardware was indeed quite solid and attractive. Such a shame I can’t say anything good about the software though.

As you would expect, I had to first configure the camera over a wired link. By default the camera comes up on 192.168.1.10. The login credentials are the usual “admin/admin” – which is the first thing you should change, but sadly I’ll bet that few people bother. The web interface presents the user with a set of configuration menus on the left of the screen and an image taken from the camera towards the centre of the screen. The software assumes that the user has IE and ActiveX running so for those of us with more sensible setups, some of the configuration and control options on the camera (such as snapshot, zoom and audio volume control) are unavailable. No matter, the important thing from my point of view, and the reason I bought this camera rather than its slightly cheaper brother, the SC3130, is the supposed wireless capability. At first sight, the camera and network configuration options look surprisingly comprehensive. In fact, I’d go so far as to say that the list of options available might confuse a user who had little networking experience. For example, besides the obvious options to set new static IP addressing or change to DHCP, you can change HTTP, RTP and RTSP ports, set up multicast streaming, change the multicast address, change the ports used for video and audio streaming, set viewer authentication, set the camera to use PPPoE and dynamic DNS and even send users an alert via email containing the new network settings (such as IP address) should these change. Of course, in order to do so the user must first configure email on the camera. Altogether an impressive looking range of capabilities. Again, such a shame they don’t all work.

Annoyingly, the web interface sometimes simply refused to accept changes or the system reset the changes after reboot, I first noticed this when changing the camera’s clock setting to sync with the time on my PC. It simply refused. NTP worked eventually, but it tended to stop working for no apparent reason. But by far the worst fault was in the WiFi stack. WiFi configuration options were all accepted and it was soon possible to connect wirelessly both to configure the camera and to view either a video stream or a still image. However, as soon as the wired connection was removed, both interfaces went down. Nor was it possible to connect wirelessly if the camera was booted without a cable inserted. Now it is pretty pointless to have a WiFi camera that insists on having a wired connection present as well and I couldn’t believe that no-one had tested this so I assumed that there was some way to get the thing working. Besides I hate being beaten. So I spent what was, on reflection, a disproportionately silly amount of time playing with various configuration options (DHCP vs static addressing, various combinations of UPnP and no UPnP (which involved me changing my router configs as well), changing various network port numbers, all to no avail. I searched the manufacturer’s website in case there was a new firmware image I could try, but that was a waste of time because the image on the website (1.6.17 dated 29 October 2010) was older than the firmware on the camera (1.6.18 dated 17 March 2011).

After trying umpteen variations of settings, at one point the camera froze completely and refused to boot. I had to resort to a hardware reset to get the thing back up again. Here it got weirder still. The camera came back up on 192.168.1.97 and not the default 192.168.1.10 (I found it with a sniffer). God help the average punter trying to get this thing to work.

I sent it back, and amazon refunded my money. Do yourself a favour. Don’t even think about buying one.

I’m not entirely convinced of the merit of the site in the first place (and can see all sorts of potential objections arising in some of the more rabid tabloid newspapers), but I thought I would try it out before making any form of judgement of my own. Unfortunately I’m not impressed.

The opening page of the new service invites the user to “Enter your postcode, town, village or street into the search box below, and get instant access to street-level crime maps and data, as well as details of your local policing team and beat meetings.”

I have tried various combinations of the suggestions, scaling outwards and upwards from my precise postcode to the whole of that part of the County in which I live. I was not reassured to get the following message:

Discussion elsewhere on the ‘net suggests that this result is not unusual. It appears to be a badly worded (or badly coded) response to an error condition resulting from system overload following the launch. At least I sincerely hope that is the case and we are not really completely devoid of policing services in the whole of South Norfolk.

Examination of the HTML source for the webpage generated suggests that the service is running on Amazon’s Web Services. Certainly some of pages are retrieved from S3 servers, and the IP address of the site appears to be on Amazon’s AWS (see dig and whois results below *). If the site is, as it appears to be, cloud based, then either the supplier (Rock Kitchen Harris, Leicester) or the Home Office has seriously undersized the requirement. Regardless of who is at fault here, there is an evident need to pull in some more resource pretty quickly. This should be a good test of the much vaunted flexibility of cloud based services such as Amazon’s EC2. I expect the service to be running quickly and cleanly by this time tomorrow.

* dig www.police.uk returns:

; <<>> DiG 9.6-ESV-R3 <<>> www.police.uk
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 10557
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;www.police.uk. IN A

;; ANSWER SECTION:
www.police.uk. 1251 IN CNAME policeuk-167782603.eu-west-1.elb.amazonaws.com.
policeuk-167782603.eu-west-1.elb.amazonaws.com. 60 IN A 46.137.113.146

;; Query time: 268 msec
;; SERVER: 80.68.80.24#53(80.68.80.24)
;; WHEN: Tue Feb 1 14:16:23 2011
;; MSG SIZE rcvd: 107

and a whois lookup of 46.137.113.146 returns:

% Information related to ’46.137.0.0 – 46.137.127.255′

inetnum: 46.137.0.0 – 46.137.127.255
netname: AMAZON-EU-AWS
descr: Amazon Web Services, Elastic Compute Cloud, EC2, EU

First I spun up a completely new clean install of ubuntu in a virtualbox VM. Then I downloaded the latest chrome .deb from the google site and installed it. Before launching chrome for the first time in the guest system I fired up the sniffers in the host system. This is what I found:

Note that etherape shows five connections which are instantly recognisable as going to google servers (the 1e100.net domain), three to verisign, and a further three to IP addresses with no associated names (these appear to be either youtube or google image cache machines – also owned by google of course). You can ignore the rlogin.net servers, they are all mine.

A quick look at the tcpdump record shows that the verisign connections all check for SSL certificates and/or revocations – perfectly sensible and understandable. But the google connections are less illuminating until you follow the tcp streams. Two of the connections are SSL encrypted so it is not possible to be certain what is carried in them, but they appear to be certificate exchanges (or updates), a third gets a certificate revocation list whilst two more get simple html or xml schema probably associated with building the welcome screen (I didn’t explore in detail). One connection gets a shockwave flash file and two get and set cookies in the youtube domain. At least one of the google connections also gets and sets cookies in the google domain.

Now none of this is inherently suspicious (well, alright, it might be) but the point is that all this happens upon first connection and without reference to the user. And if you don’t want google (or youtube) cookies on your machine you will have to delete them when first you use the browser. I have an instinctive (OK, partly irrational) dislike of software which “phones home” without telling me – and chrome does that on quite an impressive scale. I’m not sure what would happen in prolonged usage of the browser because I wasn’t impressed enough to want to use it in anger.

I’ve trashed the VM of course.

I have no idea why my earlier experiments failed.

I fund fast exit nodes as a way of paying something back to the community – but as I have pointed out before, they also allow me to have a permanent entry point to the tor network which I can tunnel to over ssh, thus protecting my own tor usage from snoopers. For some time I used a configuration based on tyranix’s notes documented on the tor project wiki. But eventually I found that to be rather limiting because it meant that I had to remember to run an ssh listener on each machine I used around the house (my laptop, netbook, two desktops, my wife’s machine etc) and to configure the browser settings as necessary. Then I hit upon the notion of centralising the ssh listener on one machine (I used the plug) in a sort of ssh proxy configuration. This meant that I only had to configure the local browsers to use the central ssh listener as a proxy and everything else could be left untouched. It also has the distinct advantage that my wife no longer has to worry about anything more complex than switching browser when she wants to use tor.

But I hit a snag when initially setting up ssh on the plug. For some reason (which I have never successfully bottomed out) the ssh process dies after an hour of inactivity. This is not helpful. Enter autossh. Using autossh means that the listener is restarted automagically whenever it dies so I can be confident that my proxy will always be there when I need it.

Here’s the command used on the plug to fire up the proxy:

autossh -M 0 -N -C -g -l user -f -L 192.168.57.200:8000:127.0.0.1:8118 tornode

That says:

- M 0 – turn off monitoring so that autossh will only restart ssh when it dies.
- N – do not execute a command at the remote end (i.e. we are simply tunneling)
- C – compress traffic
- g – allow remote hosts to connect to this listener (I limit this to the local network through iptables on the plug)
- l user – login as this user at the remote end
- f – background the process
- L 192.168.57.200:8000 – listen on port 8000 on the given IP address (rather than the more usual localhost address)
- 127.0.0.1:8118 tornode – and forward the traffic to localhost port 8118 on the remote machine called tornode

Of course “tornode” must be running ssh on a port reachable by the proxy. Again, I use iptables on tornode to limit ssh connections to my fixed IP address – don’t want random bad guys knocking on the door.

Now on tornode I have polipo listening on port 8118 on localhost. I used to use privoxy for this, but I have found polipo to be much faster, and speed matters when you are using tor. My polipo configuration forwards its traffic to the tor socks listener on localhost 9050. I also disabled the local polipo cache (diskCacheRoot = “”) because leaving it enabled means that the cache (by default /var/cache/polipo) directory will contain a copy of your browsed destinations in an easily identifable form – not smart if you really want your browsing to be anonymous (besides, my wife deserves as much privacy as do I).

The final bit of configuration needed is simple. Set your chosen browser to use the proxy on port 8000 on address 192.168.57.200. Since I use firefox for most of my browsing, I simply use opera for tor and I have that browser stripped to its basics and locked down as much as possible. Using tor is then simply a matter of firing up opera in place of firefox. This means that I always know when I am using tor or not (and just to reassure myself, the opera homepage is the torcheck page).

You can’t be too careful.