Archive for the 'Internet' Category

“My IP is blocked by a repressive regime, can I have a different one?”

Sunday, July 7th, 2013

I asked this question on Twitter yesterday and got a wider range of responses than I expected, although from a limited number of people. So I wondered what others would think. Say you sell virtual machines and a customer says: My service allows journalists and others inside repressive regimes to get their stories out. My […]

Scanning for open recursive DNS resolvers

Friday, January 11th, 2013

A few days ago we unfortunately had some abuse reports regarding customers with DNS resolvers being abused in order to participate in a distributed denial of service attack. Amongst other issues, DNS servers which are misconfigured to allow arbitrary hosts to do recursive queries through them can be used by attackers to launch an amplified […]

Converting an IPv6 address to its reverse zone in Perl

Thursday, November 29th, 2012

I’m needing to work out the IPv6 reverse zone for a given IPv6 CIDR prefix, that is a prefix with number of bits in the network on the end after a forward slash. e.g.: 2001:ba8:1f1:f004::/64 → 4.0.0.f.1.f.1.0.8.a.b.0.1.0.0.2.ip6.arpa 4:2::/32 → 2.0.0.0.4.0.0.0.ip6.arpa 2001:ba8:1f1:400::/56 → 0.0.4.0.1.f.1.0.8.a.b.0.1.0.0.2.ip6.arpa I had a quick look for a module that does it, but […]

Linux, IPv6, router advertisements and forwarding

Sunday, September 4th, 2011

By default, a Linux host on an IPv6 network will listen for and solicit router advertisements in order to choose an IPv6 address for itself and to set up its default route. This is referred to as stateless address autoconfiguration (SLAAC). If you don’t want a host to automatically configure an address and route then […]

My email marketing adventure with British Telecom

Friday, August 5th, 2011

The saga so far I have a phone line from BT. I only use it for ADSL (which I get from Zen Internet). I gave my email address to BT because they offered to tell me useful things about my account via email. I now wish I had never done this. I use extension addresses […]

Domain name as hostname not recommended

Friday, June 10th, 2011

I had an interesting support ticket yesterday. Someone was trying to do an apt-get update via BitFolk‘s apt cache and was ending up connecting to 2607:f0d0:1003:85::c40a:2942, where it was failing to update. This is not a BitFolk IPv6 address, nor is it the IPv6 address of a Debian mirror. Where was it coming from? I’d […]

Mass-setting the default view mode for cacti

Wednesday, May 18th, 2011

Recently it came to my attention that many of BitFolk‘s customers were finding our Cacti install confusing. The main problem was that upon logging in they were confronted with the default graph view – the “Tree View” – and they didn’t understand where they might find the relevant graphs within this tree. Experienced Cacti users […]

StartCom’s free SSL certificates

Monday, March 14th, 2011

I’ve been wondering what the downsides are with StartCom’s free SSL certificates. At the moment those seem to be: You can only renew them for 1 year – could be tedious if you have lots of them. Windows XP users need to have installed at least Service Pack 2 to have the CA. Apparently non-updated […]

Some Internet history from Vint Cerf

Sunday, April 4th, 2010

I’ve been following a thread on NANOG about why the first versions of the Internet Protocol supported only a maximum of 256 different networks. Back then, every organisation on the fledgling Internet got a range of IP addresses starting with a digit 0-255 and used the next three digits to number their hosts. eg. 192.168.3.4. […]