I recently purchased a Dual Opteron HP Proliant and decided today to install Debian on it. The first problem is that there is no CD/DVD in it. I know I could have just ripped one out of another PC but I decided to do things a bit differently.
Basically I wanted to install Debian on the machine and the simplest way to do this if we are not allowed to use a CD is to use PXE and some ingenuity.
These are a rough set of steps I followed
apt-get install tftp-hpa and tftpd-hpa
You will also need a dhcp server and a resolver
apt-get install dnsmasq dhcpd
mkdir /tftpboot
grab The debian net insall bits
cp netboot.tar.gz /tftpboot/
cd /tftpboot/
tar -zxvf netboot.tar.gz
chown -R nobody:nogroup /tftpboot/*
edit /etc/xinetd.conf and add the following
service tftp
{
disable = no
socket_type = dgram
protocol = udp
wait = yes
user = root
server = /usr/sbin/in.tftpd
server_args = -s /tftpboot
}
/etc/init.d/xinetd restart
add the following to /etc/dhcp3/dhcpd.conf
host box2 {
hardware ethernet 00:00:1a:19:4e:7c;
filename “pxelinux.0”;
fixed-address 192.168.1.10;
}
subnet 192.168.1.0 netmask 255.255.255.0 {
range 192.168.1.20 192.168.1.30;
}
add the following to /etc/dnsmasq.conf
interface=eth1
dhcp-host=00:00:1A:19:4E:7C,box2
For those using an iptables firewall
iptables -A OUTPUT -p udp -o eth1 -j ACCEPT
iptables -A INPUT -p udp -i eth1 -j ACCEPT
iptables -A INPUT -p udp -i eth1 –dport 67:68 –sport 67:68 -j ACCEPT
iptables-A INPUT -p udp -i eth1 –dport 67:68 –sport 67:68 -j ACCEPT
iptables-A OUTPUT -p udp -o eth1 –dport 53 -j ACCEPT
iptables-A INPUT -p udp -i eth1 –sport 53 -j ACCEPT
Set the client machine to use network boot and restart it and hey presto a Debian installer. I chose linux26 at this point because I am using SATA disks with an Adaptec 1210SA controller.
ssh Notes
I had an odd problem using ssh that stumped me for a bit.
Using ssh -vvv user@host
Cutting out all the fluf we see that normally (when using a public key) we get something like the following
……………………
debug1: Next authentication method: publickey
debug1: Trying private key: /home/user/.ssh/identity
debug3: no such identity: /home/user/.ssh/identity
debug1: Trying private key: /home/user/.ssh/id_rsa
debug3: no such identity: /home/user/.ssh/id_rsa
debug1: Offering public key: /home/user/.ssh/id_dsa
debug3: send_pubkey_test
debug2: we sent a publickey packet, wait for reply
debug1: Server accepts key: pkalg ssh-dss blen 433
debug2: input_userauth_pk_ok:
debug3: sign_and_send_pubkey
debug1: read PEM private key done: type DSA
…………………..
I noticed that I had changed the perms on the users directory from
drwxr-xr-x 33 user user 2048 Aug 14 18:57 user
To
drwxrwxr-x 33 user user 2048 Aug 14 18:57 user
This meant that I lost access using public keys. The verbose output with this error is as follows.
………….
debug3: authmethod_is_enabled publickey
debug1: Next authentication method: publickey
debug1: Trying private key: /home/user/.ssh/identity
debug3: no such identity: /home/user/.ssh/identity
debug1: Trying private key: /home/user/.ssh/id_rsa
debug3: no such identity: /home/user/.ssh/id_rsa
debug1: Offering public key: /home/user/.ssh/id_dsa
debug3: send_pubkey_test
debug2: we sent a publickey packet, wait for reply
debug1: Authentications that can continue: publickey,password,keyboard-interactive
debug2: we did not send a packet, disable method
debug3: authmethod_lookup keyboard-interactive
debug3: remaining preferred: password
debug3: authmethod_is_enabled keyboard-interactive
……………..
Removing group writable permissions from the users home directory solved the problem.
Subversion Notes
Notes to self about subversion.
To get the permssions right read the following.
RedBook
What follows is probably a butchers job.
#!/bin/sh
REPO=/usr/local/subversion
if [ -d $REPO ]; then
echo “Repository already exists”
exit 1;
fi
mkdir $REPO
chown svn:svn $REPO
chmod +s $REPO
chmod g+w $REPO
svnadmin create –fs-type fsfs $REPO
cd $REPO
chmod g+w db
chmod g+w db/transactions
chmod g+w db/write-lock
chmod g+w db/revs/
chmod g+w db/revs/*
chmod g+w db/revprops
chmod g+w db/revprops/*
Abbey Business Account Shambles
If I were to ask you what the most fundamental things a bank must never do I am sure there are a few who would pick the following answer.
Loose your money
To open an abbey business account you need to deposit £50+ worth of cash. I opened an account with £120 and guess what? The account opened but the money was missing.
I have spent several weeks trying to get through to someone on the phone about this matter. I spoke to someone a few weeks ago at the weekend and was told I had to call them during the week but they would get someone to call me. Guess what, no call.
I went with this Business Account because it looked like a good deal but I am slowly realizing that it might not have been a good idea, their customer service is severely limited. Every time I phone during the week I get held up in queues for twenty minutes.
As an update: It took me two years to get the money. Yes, they kept the money for 24 months. If I was to withhold money from any company that long I would end up in court. However, I was warned that if I tried to take them to court that I might not get the full amount back especially if I did not put in enough effort to get it. It seems crazy that a company can hold your money and then you need to work to get it back out of them.
Abbey never apologized or gave me any interest on this money. Surely there must be some law in the UK to protect people against this sort of behaviour?
Layered Technologies
I have just been combing through the logs because I have been getting hit quite hard recently and was wondering who by and I noticed the strangest thing.
I noticed the following IP address was cropping up under different referrers.
216.32.75.122
I also found the following blog entry about Layered Tech supporting referrer spam
So far I have noticed them masquerading as the following referrers.
Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; FunWebProducts-MyTotalSearch; SV1)" 1 www.uklug.co.uk Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)" 0 www.uklug.co.uk Mozilla/5.0 (compatible; Yahoo! Slurp; http://help.yahoo.com/help/us/ysearch/slurp)" 0 www.uklug.co.uk Mozilla/2.0 (compatible; Ask Jeeves/Teoma; +http://sp.ask.com/docs/about/tech_crawling.html)" 0 www.uklug.co.uk Mozilla/5.0 (compatible; BecomeBot/2.3; MSIE 6.0 compatible; +http://www.become.com/site_owners.html)" 0 www.uklug.co.uk aipbot/1.0 (aipbot; http://www.aipbot.com; aipbot@aipbot.com)" 0 www.uklug.co.uk
Mathematics
I’m doing a Mathematics degree with the Open University and I am in my first two of the 4 required level 3 subjects.
I have not really had as much time as I would like to devote to Maths, so, for the most part, I have been reading the material and finishing the course work with as little paper and pen as possible. This system of doing things was working fine up until a few weeks ago when I started to run into trouble with M381 (Number Theory and Mathematical Logic).
The questions in this course have demanded a rigour that has not really been set out in previous courses. When asked “Prove the Following” I was completely baffled and had no idea where to start. This might sound odd for those people who are up to speed with their Math but for me it was an eye opener. For those maths teachers out there you may recognise that I have become a calculator and not a thinker (my own fault) which is fine for doing sums but pretty useless for real Mathematics.
Anyway. Not to be outdone I decided that the only way to get up to speed was to subject myself to more Maths, specifically, more thinking about Maths. I went looking for a text that would have the rigour I was looking for and having searched high and low one text that seemed to appeal was A Course of Pure Mathematics by G. H Hardy
I have been trying to get to grips with this book over the last few weeks and so far I have made the following observations.
The book states in the preface:
This book has been designed primarily for the use of first year students at the Universities whose abilities reach or approach something like what is usually described as “Scholarship Standard”
I am “meant” to be covering 3rd year level material in my degree and a lot of the material in this book appears new to me. This begs the question[s].
- Have I forgot what I learned previously?
- Have I not understood the material in previous courses?
- Has the standard slipped since Hardy’s time?
There are more questions I could ask but these questions alone scared me into checking Google groups for more information and I found the following article on Littlewood which made me think that perhaps the required standard was higher in those days.
Having thought about this for a while I decided that “standards being higher” was a weak excuse at best, and that I should really not be casting historical aspersions when I’m hardly capable of judging a decent book from a bad one due to my lack of mathematical maturity. This left me in a bit of a dilemma.
- I want to get better at Maths.
- I have only so many hours in the day (I have bills to pay).
- I need to teach myself.
The criteria above mean I need to pick an area of mathematics in which I will continually find myself in, regardless of what maths I am doing. From what I could gather there are a few areas that seem to crop up all over the place. Two of these subjects are Calculus and Analysis (I know they are similar subjects), they seem to find their way into everything to some degree or another.
To this end I have decide to spend some of my spare time doing problems from calculus and analysis books. I have also bought Polya’s “How to solve it and am about half way through it” and so far it has been an interesting read.
I have ordered Spivaks Calculus book. I would also like a few other books to read around the area a bit. Again the source I went to for information on this was sci.math. The books I intend to investigate are as follows.
- Calculus: T. M. Apostol
- Calculus: Spivak (on order)
- Calculus Answer book: Spivak (Answer book) (on order)
- Introduction to Calculus: Courant, John
- Mathematical Analysis: T. M. Apostol
- Real Anlysis: Royden
- Principles of Mathematical Analysis: Rudin (Baby)
I don’t intend to purchase all of the above books although it would be nice to have them. The above list seems to be the most popular recommendations on sci.math (particularly Spivak, it has an answer book so I ordered it). I intend to have a look at each of them and decide which ones would be best suited for me.
I have also heard good things about:
What is Mathematics: Courant Robbins Stewart
which I have been meaning to buy for a long time. Current books I own are:
- A Course of Pure Mathematics: Hardy
- Differential and Integral Calculus: Courant Vol 1 (Old Blackie edition).
- Calculus Made Easy: Silvanus P Thompson and Martin Gardner
- An Introduction To the Theory of Numbers: Niven and Zuckerman
- An Introduction To the Theory of Numbers: Hardy and Wright
- Fundamentals of Number Theory: William J. LeVeque
- Advanced Mathematics (A pure Course): Perkins and Perkins
- Engineering Mathematics: K. A. Stroud 4th Ed
- How to solve it: Polya
- Fermats Lat Theorem: Simon Singh
- A concise History of Mathematics: Dirk J. Struik
- Introductory Logic and Sets for Computer Scientists: Nimal Nissanke
- A History of Mthematics: Victor J. Katz
Why blog
When asked why he wanted to climb Mount Everest the climber George Mallory answered,
Because its there
This was a fantastic answer and I wish I had an original one liner to answer the original question. My paltry answer is:
I blog because I blog.
Google Premium Adsense
I currently use Google Adsense and was wondering just how many hits a second I would need to be receiving in order to apply for their Premium service
You need to be getting 10 million content views per month. This is not the same as hits because images, spider hits etc don’t count.
Last month I got approximately 1020358 hits which sounds impressive but it isn’t that great because this only got me 102,636 content views on google adsense as per their own stats. So approximately every ten hits I get 1 content view.
Using some advanced mathematics based on our very accurate assumptions 😉 This means I need approximately 100 million hits a month to achieve 10 million content views. This is of course pie in the sky.
This is about 40 hits per second. I doubt very much if my little sever would be able to withstand that kind of usage 😉 I suppose if I was getting that many hits per month then I would be able to afford a whole rack full of equipment.
Emotive entries
Is it just me or do more emotional entries on blogs get more hits. The reason I ask this is due to an entry I made just recently.
I’ve had more comments on that one topic than any other. In fact, its been the most popular topic on my blog for a couple of months. Admitedly this is not a huge achievment but I have found the more controversial or emotional the entry the more comments it seems to collect.
FT Search Engine Spam
Just noticed the following on Jeremy Zawodny’s blog. This is a pretty shit way to make money.
Basically moneysupermarket.com have paid the Financial Times (FT) to add some hidden links to their website. Of course when Google finds the link it will assign a hefty amount of PageRank to the page that’s linked to (FT has a PageRank of 8). I wonder how much the ask for this type of service.
Google’s Quality Guidelines specifically states:
Quality Guidelines – Specific recommendations:
* Avoid hidden text or hidden links.
I wonder what the penalty is (if any) for this sort of search engine spam. I don’t do it for fear of loosing what little Ranking I have with Google. I suppose I could report them but I doubt anything would be done to the FT.
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