Using reverse proxies to unify web sites

At least around here, it's common for a department to have a number ofdifferent administrative groups inside of it, all of them providingservices (whether internal or external). Generally this produces aprofusion of group websites, partly because each group has differentneeds and partly so that no single group is stuck with the job of beingresponsible for a web server that contains everything, includingpeculiar applications that they don't understand and can't touch.

It's recently struck me that one of the


One limitation of internal charges

One of the things that is popular in universities and companies ischarging for internal services. The hope is that this will causepeople to be 'efficient' in both what services they use and how theyprovide services, much as if the various groups were real companiesdoing business with each other. However, this is an illusion.

One of the ways that this is an illusion is that a university cannotlet a consumer group fail if it cannot pay its bills or doesn't haveany money, the way a


A gotcha with Solaris Volume Manager metasets

Here is something that I have learned the hard way: at least on Solaris10 x86, you cannot create a metaset unless you have a local metadb. Itcan be completely empty, but you have to have one to start with, evenif you are never going to create any local meta-disks and the like.

This is a non-trivial issue because you have to put that local metadb ona disk partition and a default Solaris install doesn't create any spareones. The result


On the naming of machines (part 2)

I've recently been forcefully reminded of an important thing about naming machines , namely that you should give yourmachines hostnames that are not English words that you will use inyour email and notes. That way you can actually find where you mentionyour machines when you go searching through the same, instead of gettinglost in the clutter.

(For example, we had a machine called 'mix'. I rapidly gave up searchingour work email archive for information about its history.)

This doesn't mean that


A limitation in Linux's policy based routing

One of the more advanced things you'd like to do with Linux's policybased routing and a dual identity scenario isto be able to make more flexible decisions about what goes out whatinterface. Consider the case where you have two internet connections,one slow but reliable and the other one fast but currently flaky, andyou have a different IP address on each. You would like to send notso important traffic (such as web browsing) over the fast but flakyconnection while still having important traffic like


Weekly spam summary on August 25th, 2007

This week, we:

  • got 10,965 messages from 236 different IP addresses.
  • handled 18,098 sessions from 1,724 different IP addresses.
  • received 376,478 connections from at least 114,062 different IPaddresses.
  • hit a highwater of 18 connections being checked at once.

Things are down a bit from last week ,but we are still being hammered by spammers, mostly using compromisedzombies. The per day


Linux and accidentally multipathed disks

We have one Dell 2950 that has a PERC 5/? RAID controller, bought assomewhat of an experiment, and Ubuntu 6.06 has an interesting problemwith it: the kernel sees both the real disks and the PERC RAID devices(in that order), with the RAID devices being slightly smaller (thePERC controller seems to use a bit of space at the end of the disk,presumably to store its setup information.)

As you might expect, having the same disk visible through


The excessive cleverness of some people's reverse DNS

I have to say that I'm bemused by the amount of effort that people willgo to just to avoid coming up with hostnames for their machines. (Thisis different from the lazy people, who just don't bother creating PTR records at all.)

By now I am used to the people who carefully give their IP addressesa PTR record of the IP address itself:

2.0.0.127.in-addr.arpa. PTR 127.0.0.


Redirecting traffic to another machine with Linux's iptables

Let us suppose, as a not entirely hypothetical example, that you haveadded an A record for your subdomain name that points to one of yourlogin servers, so that people can do 'ssh subdomain' and have it work.Let us further suppose that this login server is not your web serverand you now want to make https://subdomain/ also do something useful,instead of giving connection refused errors.

One way to do this is to use iptables on the login server to redirectany connections to


The dilemma of website facing

Broadly speaking, websites can be inward facing, aimed at providingservices to people in your organization, or outwards facing, aimedat providing information (and sometimes services) to outsiders. Thedifference is not just a matter of keeping sensitive information fromoutside people, it is that the two groups generally want completelyseparate sorts of information; the procedures for arranging workstationsupport are probably as uninteresting to outsiders as the press releasesare to insiders.

I think that this gets especially confusing in universities, becausegroups in a university have