Archive for the ‘networks and networking’ Category

ssh through http proxy

Saturday, March 1st, 2008

On a mail list I subscribe to I have recently been involved in a discussion about the restrictions sometimes placed on users of WiFi hotspots or hotel networks (to say nothing of the restrictions placed on corporate networks). Some of the suggested solutions involve tunnelling ssh connections over http(s). Other solutions assume that the network is simply restricting access with packet filters so that you may just need to connect to a non-standard port (such as 80 or 443). If this is the case, then you simply have to configure your target ssh daemon to listen on that port. However, some networks force you through a proxy, in which case you need a utility like corkscrew. I had not previously heard of this neat little utility – but it turns out to merit some exploration if you find yourself needing such a tool.

Corkscrew is relatively simple to set up, but if you have problems, take a look at Andrew Savory’s blog entry of 27 February 2008.

another vulnerability in the home hub

Saturday, January 19th, 2008

The guys at gnucitizen have posted details of another vulnerability in the BT home hub (and related Thomson routers). This vulnerability allows a remote attacker to reconfigure the router using the UPnP functionality which is turned on by default. UPnP is an authenticationless protocol designed to allow local devices to reconfigure the router – typically to allow insertion of port forwarding rules or similar changes to the firewall. On the Thomson routers (and the home hub) UPnP configuration can be found under “Game and Application Sharing” on the web configuration interface.

If you haven’t already done so, I recommend that you turn off UPnP. There is no good reason to leave it on. If you find that some device on your network needs a particular port forwarding rule to be set, then set it manually. Better still, consider whether you really need that device on your network.

reflashing the BT home hub from a linux PC

Sunday, December 30th, 2007

As I mentioned in an earlier post, I found several references to successful reflashes of the BT hub to a genuine Thomson 7G image on a variety of sites. None of those sites gave instructions as to how to do this if you run a linux PC.

So I have documented how I did it here.

homehubblog goes off-line

Saturday, December 15th, 2007

Some of my earlier posts have referred to the “homehubblog”. The author of that blog seems to have had his domain name stolen from under his feet. The address given now links to an estate agent site. I know that there are robots out there just waiting to pounce on domains which come up for renewal so that existing traffic to established sites can be hijacked, but this is just ridiculous. I strongly recommend that anyone using a domain they value get it locked by their ISP or domain manager so that renewal in their own name is automatic.

Needless to say, any references to the homehubblog in my earlier posts should now be ignored – they just won’t work.

leaving BT Broadband

Saturday, December 15th, 2007

My contract with BT has now expired and I am shortly to move my ADSL connection to one of the Entanet resellers (TitanADSL). All the Entanet resellers I have read about get good reviews. I picked TitanADSL because they offer additional webspace and mySQL databases on top of their broadband service. With luck my IP service will improve hugely (BT consistently throttle service at peak times) and I know that my “support” service will improve beyond recognition.

I know I shouldn’t have bothered, but I actually made the mistake of emailing BT Broadband “support” requesting a MAC (Migration Activation Code) so that I could get my new supply sorted. I received the response below. I cannot believe that I actually received an email from someone “trying to be part of the solution”. Needless to say I received no MAC so I phoned the number given on the the BT website and got the code over the phone in minutes.

——–
BT Email

Dear Sir / Madam,

Thank you for your e-mail dated 6/12/07 regarding your request for MAC code.

With regards to your email, I would like to inform you that I have to forward this matter to the relevant team for further assistance. Therefore, I would request you to kindly forward your account details, i.e. the customer account number and the telephone number in reply. We need this information for security reasons, as well as to access your account and assist you further.

I can assure you that on receipt of your account details we will assist you in an appropriate way and will make every possible endeavour to solve your concern as soon as possible.

I realise that I have not been able to resolve your concern immediately. I can assure you that I am trying my best to be a part of the solution and in the meantime I would like to thank you in anticipation of your continued patience and co-operation, and to assure you of our best intentions at all times.

Thank you for contacting BT.

Yours Sincerely,
eContact Customer Service

more on the BT home hub

Sunday, November 25th, 2007

I last wrote about the BT Home Hub (HH) nearly a year ago. Looking back, I spent an unreasonable amount of time trying to get BT “support” to even bother to read, let alone understand, my problems. Eventually I gave up in disgust. Here I was fortunate because I had substituted a genuine Thomson ST780 router for the castrated pile of rubbish that BT provide. I had also junked the BT VOIP service (which I never successfully got working – despite having paid for it) in favour of the excellent service provided by sipgate

I have since had occasion to revisit the HH because an email list I subscribe to started a thread about it (guess what, no-one likes it…) so I looked again at some old links – such as the homehubblog. I also found some new links which look interesting, in particular the home hub hacks site which suggests that it might be possible to reflash the HH with a genuine Thomson image (though some of the links from that site are broken). Now having a couple of extra, cheap Speedtouch routers would be cool. And since you can pick up HHs on ebay for around a tenner (see, I told you no-one likes them) I feel a new hobby coming on.

I currently have two HHs. neither of which I use, and both of which I can afford to brick – so I’m going to play.

update on the Reg about BT and the GPL

Thursday, February 8th, 2007

I knew this one would run…..

The Register notes that BT believe they have done enough to comply with the GPL by publishing the code here. But the Free Software Foundation remains unconvinced. In my view BT should respond more positively and work with the foundation to meet the requirements of the GPL.

We’ll see.

BT home hub and the GPL

Monday, January 22nd, 2007

I mentioned the Home Hub Blog in an earlier post. That author of that blog (amongst others) has been trying to find a way to unlock the Hub so that it can be used on ISPs other than BT itself. Unfortunately, BT seems to have tied the beast down (and ties it further with each upgrade of firmware). Worse, most users will be oblivious to the fact that BT can, and does, upgrade the Hub remotely. This may suit BT, but it does not suit all its customers – myself included.

The Home Hub blog author noted that the software in the Hub is a variant of an embedded Linux, with some additional code such as Samba. Given that all this code is covered by one or more variants of the GPL, BT is obliged to release the entire source code to anyone who asks, Access to the source code would, of course, allow anyone to identify where BT have locked the Hub, change it, recompile and reflash the Hub into an unlocked state. So HomeHubBlog wrote to BT – and he eventually gained a partial response. But not enough. See the Register article at The Register. This one could run and run.

My own experiments with the Hub tell me that it runs a Linux kernel 2.6.8.1. The FTP daemon on the Hub is so flakey however, that getting consistent access to the filesystem is very hit and miss. I commented on the Home Hub Blog at playing-around-with-ftp so I won’t repeat it here.

Several commentators have mentioned methods of getting root (superuser) access to the Hub CLI and FTP accounts. The method I have found most consistently successful is as follows:

Telnet to the Hub and log in as admin. At the command prompt type “user”, then type “flush” (this deletes all users). Now log out and log back in again, but this time log in as “root” (no password needed). Now go back to the user command subset and type “add”. Follow the prompts as below:

name=root

password=[your chosen password]

password=[repeat your chosen password]

descr=root (or any other description)

defuser=[leave blank - answering yes would make this the default user on login]

defremadmin=[leave blank - answering yes would make this the default remote admin user]

deflocaladmin=[leave bank - answering yes would make this the default local admin]

Bingo, you now have a root user. Now repeat the process for a named user (such as yourself) but give yourself the Administrator role. Make this user the default and the default local admin. Now save the configuration by going back to the top level of the CLI prompt system (type “..” to go back) and type “config save filname=user.ini”.

Note however that BT can overwrite this configuration, so you need to disable that. To do so you need to switch off CWMP (the CPE WAN Management Protocol) capability which allows BT to manage your router remotely. Bear in mind, however, that doing so will prevent BT automatically updating your router software if security problems are found – caveat emptor. To turn off CWMP, do the following:

at the top level CLI prompt, type “cwmp”, then at the cwmp prompt, type “config state=disabled”.

Your router is now unreachable.

(Again, you will need to save this configuration if you want this change to survive a reboot.)

another update to correspondence with a corporation

Wednesday, January 17th, 2007

Since my last post at the end of last year I have been testing my ST780 with a variety of alternative VOIP providers whilst at the same time trying to get BT to sort out my connection. I also lodged a formal complaint about the appalling level of technical support with the BT complaints department on 30 December.

The complaints department initially responded to me on 4 January with an acknowledgement and a comment that I could expect a fuller reply in 24 hours. On the 8th of January I received the following gem:

“BT Broadband – Complaint Management Team

Dear Sir

Thank you for your e-mail regarding the problems you are experiencing with your BT Broadband service. Please accept my apologies for the inconvenience this has caused you.

Unfortunately we are unable to assist with technical issues, we have however passed your email to our technical support team, who will be in contact with you in the next 3 to 4 working days to work towards a satisfactory resolution. Should you wish to contact the technical support desk please call 0845 600 7030.

I would again like to apologise for the problems you have experienced. I do hope this information will be of assistance to you.

Kind regards
BT Broadband – Complaint Management Team”

Since that date I have heard nothing – though I have now received my shiny new hub (which I do not intend using).

Now since the substance of my complaint was that the technical support department was neither technical nor supportive I have decided that it is futile to continue down this road and I will simply escalate my complaint (on paper) to the Customer Relations Manager.

Meanwhile, just to prove that there is nothing wrong with my ST780 router, as I mentioned above, I have been experimenting with alternative VOIP providers and have now signed up with Sipgate. Sipgate offers free VOIP services within its own network and with peer networks such as FWD. It only charges for its gateway out to the PSTN. But its charges are very reasonable indeed. Sipgate also offers a rather neat opportunity to gain a UK geographic based telephone number for no additional charge. During my testing (for free) I could successfully dial in to my new Sipgate number from the PSTN and mobile networks but initially could not dial out to the Sipgate test number. Given the problems I have with BT I contacted Sipgate support who very generously credited my account with a small test sum so that I could check outbound connectivity to the PSTN. It worked fine so I have now signed up to Sipgate’s services.

Now compare this attitude and response from a company with whom I had no contractual relationship and had paid no money with that woeful response from BT to whom I pay a very considerable sum of money each month.

BT home hub

Tuesday, January 2nd, 2007

In my searches for more information about the BT Home Hub and its configuration I have come across a couple of good sites. The Home Hub Blog is an interesting collection of notes about the author’s attempts to unlock the Hub so that it can be used on other ISP’s networks. This is the reverse of my problem which is to get BT’s network to work properly with a product other than the Hub.

Worth a read.