Xming and KDE 3.5

I often want to use an Xserver under Windows for connecting to a linux host.

After quite a while of using cygwin to acheive this, I discovered Xming which is based on the same xwindow code but is packaged specifically for providing a windows Xserver. Much simpler to use than installing and configuring cygwin which invariably involves editing the PATH variable on the windows machine and creating a suitable launch icon.

However, if your window manager on the client is KDE, you may well find that if you enable the clipboard support then the Xserver will hang immediately after login using XDMCP.

The solution to this is to edit your gdm.conf file and add the line

KillInitClients=false

in the [daemon] section

Restart gdm and you'll find that you can login and all will work.

Internal modem on a Dell Inspiron 5100 under Linux

Following an incident where I was forced to use GPRS on my mobile to connect back to work I've finally got round to sorting out the modem connection on the Inspiron 5100 that I use for remote work so that I can use it under linux.

It comes with a PC Tel soft modem which doesn't just appear as a /dev/ttyS? port.

The solution is quite simple

apt-get install build-essential module-assistant sl-modem-source

m-a update
m-a prepare
m-a a-i sl-modem

apt-get install sl-modem-daemon

This detects the modem and symlinks it to /dev/modem

Citrix Metraframe client on Linux

For a software demo we're having, I needed to install a Citrix Metaframe client. My desktop of choice is Linux and so I downloaded the linux version of the ICA client from http://www.citrix.com/English/SS/downloads/details.asp?dID=2755&downloadID=3323&pID=186

The software installed fine, as per the Admin guide, but there were a couple of extra bits needed.

Firstly the motif libraries. As I'm running debian etch, and there's no longer a debian version of the motif libraries, I had to download the .deb file for these from an old distro (sarge) and use dpkg to install it.

libmotif3_2.2.3-1_i386.deb was the file in question.

Then, having used Iceweasle (Firefox under any other name) to connect to the citrix box, I was getting 'You have not chosen to trust "Equifax Secure Global eBusiness CA-1", the issuer of the server's security certificate.' when launching one of the applications.

The solution was to go to
http://www.geotrust.com/resources/root_certificates/index.asp

and download the Equifax Secure Global eBusiness CA-1 certificates (note - use right click save as other wise you'll just be trying to install them in the browser) and then copy the files to
/usr/lib/ICAClient/keystore and restart Iceweasle

SMTP AUTH using exim and PAM

I want to use SMTP AUTH to enable road warriors to send though the office mail server - but I don't want yet another set of user names and passwords - so what I need is to use PAM to plug in to the existing Linux authentication mechanism.

This can actually be done quite easily with exim4 (the MTA that we use)

First of all, you'll want to be running the daemon-heavy debian version of exim with split up configuration files.

Then, in /etc/exim4/conf.d/auth add a local config file with:

plain:
driver = plaintext
public_name = PLAIN
server_prompts = :
server_condition = "${if pam{$2:$3}{1}{0}}"
server_set_id = $2

login:
driver = plaintext
public_name = LOGIN
server_prompts = "Username:: : Password::"
server_condition = "${if pam{$1:$2}{1}{0}}"
server_set_id = $1

You could rename these auth drivers if needed if they conflict with existing ones - or probably comment out the existing ones.

In /etc/exim4/conf.d/main set

MAIN_TLS_ENABLE = true

in a local config files (before the 03 TLS one) and

auth_advertise_hosts = ${if eq {$tls_cipher}{}{}{*}}

to only allow AUTH if TLS is running.

Then in /etc/pam.d create a config file for exim.

I have simply:

#
# The PAM config file for exim SMTP
#

# The standard Unix authentication modules, used with
# NIS (man nsswitch) as well as normal /etc/passwd and
# /etc/shadow entries.
@include common-auth
@include common-account
@include common-password
@include common-session

To make it match everything else on the host but you could tailor.

You'll need a set of certificates for the TLS communication. Self signed ones can be produces by /usr/share/doc/exim4-base/examples/exim-gencert

The final step is to make Debian-exim a member of the shadow group so that it can read the shadow passwords and actually do the authentication.


One further change I do is to prevent authenticated mails from being scanned by spamassassin.

In the rcpt acl I add

  # Prevent auth users from being scanned by Spamassassin
  warn     authenticated = *
           set acl_m0    = do-not-scan

Then in /etc/exim4/sa-exim.conf

SAEximRunCond: ${if and {{def:sender_host_address} {!match {$sender_host_address}{\N^(192\.168\.*)|(127\.0\.0\.1)$\N}} {!eq{$acl_m0}{do-not-scan}} } {1}{0}}

Which means that spamassassin won't be called for mail originating on the local network or with the acl_m0 header set to do-not-scan

Hiding accounts on XP

If you're running XP with the "chooser" login method, you can hide certain accounts from the list so that you have to do Ctrl-Alt-Del to login as them

Use regedit to access the registry and browse to

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\SpecialAccounts\UserList

Add a DWORD in there who's name is the user name in question with a value of 0

Producing encoded URLs with CGI.pm

I was in need of some URLs with the special characters (like space, & etc) escaped. They contain parameters that are being read from a database which are text search strings.

It turns out that the escape() function in CGI.pm will do what is needed - but it's not a standard function that is available when you just use CGI. You have to

use CGI qw/escape /;

to make the function available.

Web browser built in search engine links

We've started investigating linking the GoodnessDirect search page into the search box found on browsers like Firefox 2 and Internet Explorer 7.

The technique for this is actually really simple. You create an XML file to the OpenSearch standard, host it on your web server and add a reference to that in the head of your web pages.

The XML file looks something like this:

<?xml version="1.0" encoding="UTF-8" ?>
<OpenSearchDescription xmlns="http://a9.com/-/spec/opensearch/1.1/"
                       xmlns:moz="http://www.mozilla.org/2006/browser/search/">
<shortname>EngineName</shortname>
<description>EngineDescription</description>
<inputencoding>UTF-8</inputencoding>
<image width="16" height="16">ImageData</image>
<url type="text/html" method="GET" template="searchURL?query={searchTerms}">
<Url type="application/x-suggestions+json" method="GET"
     template="suggestionsURL?search={searchTerms}" />
<moz:searchform>searchPageURL</moz:SearchForm>
</opensearchdescription>

One little snag we hit was that our site makes a lot of use of extended path info as processed by Apache. This is fine with searches that are just single words or words with single spaces between them, but each space is translated into a + and the resulting ++ of two spaces causes the CGI processor to get upset. So we changed to using GET parameters for this and all is well.

The suggestionsURL above is used to produce some suggestions for the drop down box you get in the search bar. It's up to you as to how you handle this and you simply return a JSON array with the results such as:

["tofu",["tofu", "tofutti", "tofutti rock n roll cones 4x110ml", "tofutti rock 'n roll non-dairy ice cream cake 700ml", "tofutti organic vanilla non-dairy frozen dessert 750ml", "tofutti mango & passion fruit non-dairy frozen dessert 750ml", "tofutti organic strawberry non-dairy frozen dessert 750ml", "blue dragon tofu, firm silken style 349g", "taifun graffiti tofu terrine 200g", "danival organic tofu ravioli 670g", "danival organic lentils and tofu with vegetables 525g", "tofutti sour supreme 227g"],[],[]]

the first item is the term that the user entered, then you have an array of suggestions, then an optional array of descriptions of the suggestions, then an optional array of urls for the array.