Going Live with a Linux Server

Based on past mistakes by myself and others, here is a check-list before putting a Linux (or other Unix) server online:

  1. Run memtest86+ (or an equivalent program for other architectures) before going live, ideally run it before installing the OS. Run it again every time you upgrade the RAM.
  2. Reboot the machine after every significant change. EG if you install a new daemon then reboot it to make sure that the daemon starts correctly. It’s better to have 5 minutes of down-time for a scheduled reboot than a few hours of down-time after something goes wrong at 2AM.
  3. Make sure that every account that is used for cron jobs has it’s email directed somewhere that a human will see it. Make sure that root has it’s mail sent somewhere useful even if you don’t plan to have any root cron jobs.
  4. Make sure that ntpd is running and has at least two servers to look at. If you have a big site then run two NTP servers yourself and have each of them look to two servers in the outside world or one server and a GPS.
  5. Make sure that you have some sort of daily cron job doing basic log analysis. The Red Hat logwatch program is quite effective, then you need to have some way of making sure that you notice if an email stops being sent (getting 11 instead of 12 messages from logwatch in the morning won’t be noticed by most people).
  6. Make sure that when (not if) a hard drive in your RAID array dies then you will notice it.

Any suggestions on other things I can add?

Personal SEO

One problem many people encounter is the fact that they don’t appear on Google and other search engines the way that they like. If you have an uncommon name which is not referenced in any popular web pages then a single mention in a popular site can immediately become the top hit, this may not be the post you want (EG you send a dirty joke to some friends and it ends up on the archive of a popular mailing list). If you have a more common name then you may want to compete with other people who share the same name with similar problems. The solution to these problems is known as Search Engine Optimisation (or SEO).

  1. Recently to improve things in this regard I have registered the domain RussellCoker.com. Domains that end in .com are often regarded as authoritative sources of information on the topic in question, and are also often typed in to browsers. If you visit the RussellCoker.com domain then you’ll find that it’s quite bare, just links to some other things that I do. I will make it a little more user-friendly but the main aim is just having links.
  2. One thing that I have been doing for almost a decade is to include URLs of some of my web pages in my signature of email that I send. When I send messages to mailing lists with public archives (or when other people forward my mail to such lists) these links will become visible to search engines. So I now have thousands of links to my web site from hundreds of sites all over the world. Some of these links are old (which may make them more highly rated by search engines). This not only gives benefits for direct hits from search engines, but when people search for terms that are relevant to my work they will often hit archives of my mailing list postings, and then they will often see a benefit in visiting my web site.

Most strategies of SEO that apply to corporate web sites will also apply to individuals (do a web search and you’ll find many pages of advice on these issues). But the above two are the only ones I have discovered which apply specifically to individuals (registering an appropriate .com domain name if possible is a standard practice for companies and something that is done long before SEO is considered).

How to Report an Email Problem

In my work I often receive problem reports from clients regarding their email service, here is some advice to help get the problem fixed as fast as possible:

Firstly problems sending mail and problems receiving mail are often unconnected and should be reported separately. If only one aspect of a problem is reported then probably only one will be fixed… Also receiving mail via POP or IMAP is separate to the mail transfer process.

For problems on mail transfer the following points should be addressed in any report to increase the speed of problem resolution. Don’t think of this as being for the benefit of the person who fixes your mail server, think of it as being for your own benefit in getting your email working again rapidly.

  1. Make sure that every complaint has a specific example. Saying “email doesn’t work for everyone” is not helpful, often when investigating some complaints I discover that email works for many people. Saying “email doesn’t work for John Smith and other people report problems too” is helpful, I can investigate John’s problem while knowing that it’s a symptom of a larger problem.
  2. For every report make sure that you list a sender and recipient email address for an instance of the problem. Saying that “alpha@example.com can’t send mail to bravo@example.com” is much more useful than saying “alpha@example.com can’t send mail to some people“.
  3. Whenever possible make sure that the problem can be reproduced by the person who is making the report. A report such as “John Smith can’t send email from his PC” is not nearly as helpful as “I can’t send email from my PC“, the reason is that I often require more information from the person who experienced the problem and going through a third-party slows things down.
  4. Make a careful note of the time of the problem. If you report that alpha@example.com can’t send mail to bravo@example.com and the logs show that such a message was correctly delivered at 9AM I will assume that the problem was mistakenly reported and not that maybe there was a problem which first occurred at 9:30AM.
  5. When noting the time make sure you note any discrepancies. If a problem occurs at 9AM and a bounce message reports a problem occurring at 10AM then please make sure to note both times when reporting the problem. Either or both times could be referenced in the log files and the more information you provide the better the chance that the problem will be fixed quickly.
  6. Most serious errors in email delivery have a code numbered from 550 to 559 with an error message. Any time you see a bounce message which includes text such as “Remote host said: 554” then please report all the rest of the text on that line, it will often tell me precisely what needs to be done to fix the problem.
  7. Any time a bounce or other error message includes a URL then please report it to me. Sometimes it takes me a significant amount of work to discover what I could have learned in a matter of seconds if I had the URL.

Hotel Rooms vs Apartments

One option that is often overlooked is the possibility of staying in an apartment instead of a hotel room. The difference (which is not always reflected in the name) is that a hotel room usually will have a fridge that is mostly filled with over-priced drinks and has no facilities for cooking and often no facilities for cleaning clothes. A recent disappointing trend is of hotels that have a “bar fridge” that is entirely filled with things that you have to pay for which have sensors such that if any of them are moved then you have to pay. This prevents you from moving the rubbish out of the way for the duration of your visit so that you can store your sandwiches there.

An apartment will ideally have a fridge which is entirely empty for you to use for storing food and ingredients for your own cooking (it will have a minimally supplied kitchen). Apartments tend not to have a fry-pan in the kitchen, the reason for this is that they are legally required to have a smoke detector and false-alarms cause lots of problems for everyone (often it starts with an insanely loud alarm in the room which annoys everyone who is in a nearby room). You can expect to have two pots of different sizes and a toaster for your cooking.

If you are after cheap travel then the thing to do is to have cereal for breakfast and sandwiches for lunch. Finding cheap places to have lunch in a new city can take time, and finding cheap places to eat lunch near tourist attractions is almost impossible.

Some apartments have a washing machine and dryer in the room, but it’s quite common to have communal facilities for washing clothes. In any case there will be some option for washing clothes that doesn’t cost an excessive amount of money.

Another significant difference that is commonly seen between apartments and hotels is the layout (which is dictated to a large degree by the size). An apartment may have walls partially or fully separating it into separate rooms. One apartment I stayed in had two separate bedrooms (with doors), a kitchen area, and a lounge/dining area which was separated from the rest of the apartment. That made it possible to have business meetings in the lounge area while someone slept in one of the bedrooms. Another apartment I once stayed in had the bed area partially separated from the lounge area, the wall didn’t extend the full distance but covered enough that a business associate who walked into the lounge probably wouldn’t notice the bed area. There is a significant difference in principle between inviting a business associate to the lounge area of an apartment and inviting them to a hotel room…

Apartments often tend to be more expensive than hotel rooms, they need more space for the kitchen and don’t drive revenue from a mini-bar or a hotel restaurant. One possibility for saving money could be to use some inflatable camping beds to sleep four people in an apartment that is designed for two. They try and discourage this by only having enough cutlery for two people and not having spare blankets, towels, etc (I’m sure that they would bill you extra if they caught you). In contrast hotel rooms often have an over-supply of towels and blankets as it’s easier to just fill every closet with them than to deal with requests from customers at odd times of the night.

Public Transport in Melbourne

Tickets for Melbourne public transport can be purchased on any bus or tram. The trams have vending machines which only accept coins so you must have sufficient coins to pay for your ticket. Neither buses nor trams sell the cheaper tickets.

Tickets have to be validated every time you get on a bus or tram. The first time a ticket is validated it will have it’s expiry time and date printed on it.

For a Sunday there’s a Sunday Saver ticket which allows you to go everywhere (in both zone 1 and 2) for the entire day for less than the price of a regular daily zone 1 ticket. As of the 6th of January 2008 a Sunday saver ticket costs $2.90 while a ticket for 5 days of travel in zone 1 costs $28.00 (separate daily tickets cost more).

The best value for money is the 10 * 2 hour ticket (which costs the same as a 5 * daily ticket). I have been told that if you use a multiple 2 hour ticket a second time in one day outside the 2 hour interval then it will be valid for the rest of the day. This means that a 10 * 2 hour ticket will give the same result as a 5 * daily ticket if you use it that way. If your journeys tend to be shorter then it can last for more than 5 days. Also a 2 hour ticket that is validated after some time in the evening (I believe it’s 6PM) will be valid for the rest of the night (until 3AM or whenever the transport closes down).

Unique Names

Prior to wide-spread use of the Internet it was reasonable to expect that if you had a family name that was not really common and a given name that was also not really common then you might never meet someone else with the same combination of first and last names as yourself. I have never met anyone else named Russell Coker because Coker is not a really common family name and it seems that Russell was not overly common in the last 4+ decades. If you had a family name such as Smith, Ng, or Ali then the chance of having someone else with the same given name would be significant as those family names are so incredibly popular.

Even with names that are not known to be extremely popular name clashes happen, for example my sister is named Helen Coker, it doesn’t seem likely to be an overly common combination however there was another Helen Coker at the same high-school.

On the Internet however things are different. About 10 years ago I received an email from someone named Russell Coker who just wanted to say hello after having searched for his own name and found information on me. Shortly after that I found a third Russell Coker on the net (who didn’t respond to my email). It seems likely that even in the early days of the net I didn’t find everyone named Russell Coker, and it also seems quite likely that the number of Russell Coker’s on the net has increased significantly over the last 10 years. There could be dozens of Russell Coker’s although if they are using “Russell Coker” as their name on the net then I am unlikely to find them as it’s most likely that I’m the only Russell Coker to have the same email address and web site for 10 years – so my net presence probably squashes everyone else who uses that as their entire name.

A quick google search for “Russell J Coker” (John is my middle name) found one other person using that name, I also found a Russell D Coker, a Russell M Coker, a Russell N Coker, and two Russell R Coker’s (one of whom died in 2002).

It seems that if you don’t have a family name that is rarely used (EG Torvalds which was created recently) or a made-up first-name (which seems to be a popular trend nowadays) then you are going to encounter other people with the same name as you. Using an initial will significantly reduce the incidence of this, in my case if I used my middle initial then I would remove four out of five of the other living Russell Coker’s that are found by Google.

But as is the case with me it seems that many (most?) people will have name collisions no matter what they do.

As an attempt to increase my control over my name I have registered the domain RussellCoker.com. Not sure if it will do any good but it’s cheap enough and it’s worth a try.

Mobile Phone Safety

Safety Benefits of Mobile Phones

The benefits of being able to call emergency services from any location are obvious. It’s also a benefit for children to be able to call their parents at any time and without the need for change.

The ability to send videos and pictures that is included in all recent mobile phones is also a potential safety benefit. Children can send their parents pictures of the people they associate with which will deter such people from doing anything bad.

Problems With Current Mobile Phones

There has been a lot of publicity in recent times about the risks of children communicating with pedophiles over the Internet. I believe that the risks in this regard are minimal, children merely need to be supervised while using the net. I think it’s a much bigger problem is that anyone (including pedophiles) can call a child on their mobile phone, and in the case of modern phones they can exchange pictures and movies with the child! There have been many documented cases of this technology being used by teenagers to film gang violence and I believe that the incidence of teenagers making their own pornography (including videos of sexual assault) will only increase (I first wrote this document about four months before such a sexual assault was filmed and sold on DVD in Melbourne [1]).

Another significant problem is the theft of phones (which often takes the form of violent crime). For their own safety children should not be permitted to carry expensive items that can be sold easily!

Solutions to these Problems

Many of these problems can be greatly alleviated with current technology. Firstly transfer of video and pictures needs to be restricted, current phones already have configuration options to restrict which numbers may call the phone. What is needed is to have separate lists of numbers permitted to call the phone and to be called by the phone that are also separated by the type of call (voice call, video call, SMS, and video/picture SMS). A typical configuration for young children might only permit communication with relatives and emergency services. A typical configuration for older children might permit voice and text SMS communication with anyone but only permit video and picture communication with relatives and emergency services. These measures would greatly reduce the ability of pedophiles to communicate with children, and also prevent teenagers from distributing pornography and fight club movies.

Another necessary feature is the ability to restrict access to the Internet and 3G content. This has been requested by many adult customers to prevent accidentally incurring large bills. However phone companies have been refusing to do this, legislation will be required.

Such restrictions of phone use would also significantly reduce the incidence of phone theft. A phone that can only be used to call the parents of it’s owner is useless to a thief!

New Features

A new feature that is badly needed is the ability to make video calls to emergency services. In a medical emergency call a lot of time is spent describing the situation and that time could be saved if pictures were available. In the case of a crime in progress a criminal would be deterred if they knew that their picture was being sent directly to the police and stored for use as evidence at their trial.
It would require some moderately expensive new equipment to support emergency video calls and require some training of the people who receive the calls, but I am certain that the benefits outweigh the costs.

Every mobile phone has a unique ID number that it sends to the phone company when it registers. It would be easy for each phone company to keep a database of the ID numbers of all phones it sells and then when a phone is stolen it could be blocked from the network or traced by the police. A similar scheme was tried in the Netherlands where the police sent large numbers of SMS messages to stolen phones.

With a registry of stolen phones shared between all phone companies and a block on the use of stolen phones phone theft would drop dramatically.

Implementation of the Necessary Changes

Support for video calls to emergency services requires government funding. All the other suggestions I make on this page can be implemented without government involvement. It would be nice if phone companies would address these issues voluntarily, but based on past performance that seems unlikely. We probably need legislation to force them to do the right thing.

Computer Related Power Use

Below are some test results of other devices related to computers. Eventually I aim to discover some information on the best types of switches, hubs, and monitors to use for power. I include the air-filter because I believe that every small server room (IE one that doesn’t have tens of thousands of dollars spent on air-conditioning and filtering) should have a small air filter.

BenQ 17inch 1280×1024 TFT monitor active 32W
Phillips 15inch 1024×768 TFT monitor 31W
Cabletron Smartswitch 2200, 24*10baseT, 2*100baseT two PSU 52W
Cabletron Smartswitch 2200, 24*10baseT, 2*100baseT one PSU 45W
Sunbeam Air Filter (fastest) 114W
Sunbeam Air Filter (slowest) 13.9W

Here is the Computer Power Use page [1].

Conditions of Sending Email

The conditions of sending mail to my server are as follows:

  1. A signature will in no way restrict my use of your message. You sent the message to me because you want me to read it (it was not mis-sent, my mail server does not accept mis-addressed mail). I will keep the message as long as I like either deliberately or because I forgot to delete it.
  2. I reserve the right to publish any email that is threatening (including any threats of legal action). I don’t like being threatened and part of my defence is to publish such threats at an appropriate time. Anyone who is considering the possibility of threatening me should consider when their threat may re-appear.
  3. I reserve the right to publish any email that is abusive/profane, is a confession of criminal or unethical behaviour, or is evidence that the sender is a liar or insane.
  4. I reserve the right to forward all amusing email to my friends for their enjoyment.

My mail server will now provide the URL of this page to everyone who connects at the first stage of the SMTP protocol. When a mail server continues the connection that indicates acceptance of these conditions.
This doesn’t mean that I wildly forward email and business discussions are kept confidential of course. I expect that most people don’t keep mail secret when it matches the conditions in my list above, unlike most people I’m publishing the list of reasons.

Due to the popularity of this post I have created a T-Shirt and put it on sale at http://www.cafepress.com/email_eula . Wear your email disclaimer on your shirt!

Blog License

The contents of my blogs (unless otherwise noted) are licensed under a non-commercial share-alike license. This means (among other things) that you may not put my content on a web page that contains Google AdWords or any other similar advertising, and you may not use any automated system to take an RSS feed from my blog (either directly, via Feedburner, or via a Planet installation or other syndication service that includes my posts) and post it to another blog for commercial purposes (which includes attempts to increase page-rank or other SEO).

Services such as Blog Overdriv are specifically prohibited from using my RSS feed.

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported License.

As an exception to this I permit BoingBoing.net to copy my posts. I may make exceptions for some other sites on request.

Another exception is that this license may be freely copied by anyone who wants to license their blog in the same way.