Zsolt on tech

Enable Java applets for Firefox on Linux

2009-01-14T13:22:00.003+01:00

I assume that you use the default Firefox and apt-get setup.

1. Test if your browser supports Java applets here:

Java tester

2. If your browser "can NOT run Java applets", then install the Java runtime environment:

sudo apt-get install sun-java6-jre

3. Create the plugins directory:

mkdir -p ~/.mozilla/plugins

4. Link the plugin from the JRE installation to the plugins directory:

ln -sf /usr/lib/jvm/java-6-sun/jre/plugin/i386/ns7/libjavaplugin_oji.so ~/.mozilla/plugins

If your JRE got installed somewhere else, then look up the libjavaplugin_oji.so and link that file.

5. Add to ~/.bashrc:

MOZ_PLUGIN_PATH=$HOME/.mozilla/plugins
export MOZ_PLUGIN_PATH

If your default shell is not bash, then set this variable accordingly, in the startup script of that shell.

6. Log out and back, and start Firefox. Check if the installation is correct using the link at the top.

Headache gone after a solution in this blog? Then if you think... ;)

External access of a server behind Orange Sagem Livebox

2009-01-14T00:31:00.003+01:00

To open a service behind the Livebox Sagem, do the following. I use SSH as example, with port 22, and I assume that you use the default configuration of the modem.

1. Open an account at dyndns.org (I assume you know what it is, or you can figure it out. It provides you a free, fix DNS name that can "follow" the changing IP address of the modem).

2. Log in the modem as admin (default password: admin) from a machine that is behind the modem:

http://192.168.1.1

3. Set up the dyndns access properties. Select the Advanced�Menu -> Network -> DynDNS drop-down menu item. Add your dyndns user name, password and the DNS name that you selected. Press Apply, then Update Now to see if the DynDNS access is OK. You should see the green "Updated - IP updated successfully" line.
4. Now, you have two options. If you want to access the services of only one server, then you can make that particular server fully visible to the world by using DMZ. Mind that it is unsafe, because the firewall in the Livebox will not protect that machine. If you want this, then select the Advanced Menu -> Firewall -> Policies menu item, then click on DMZ host. Add the local IP address of the server, and check the checkbox. Press Apply. Done.

5. If you have more servers, or you want to protect your server with the Livebox firewall (recommended), then you must specify the services one-by-one. Select Basic Menu -> LAN Servers. At the bottom of the table, click on New Entry.�

Give a name to the service (arbitrary)
Access activated: yes
From port: 22 (the SSH server will be available on _your_dyndns_name_:22 for the world)
To �port: the SSH port of the SSH server (22)
Local IP address: the address of the server

Press Apply, and you are done.

Mind, that for an unknown reason, you cannot access the services with the dyndns name behind the Livebox. Try if from a real external machine (ex. ssh to an external server, and try ssh back to your server).

Headache gone after a solution in this blog? Then if you think... ;)

InvocationTargetException with the Apache Axis2 Eclipse plugin

2009-01-12T17:08:00.013+01:00

If you have to use Axis2, and work with Eclipse, it is worth to try this tool:

Code Generator Wizard Guide for Eclipse Plug-in

If you encounter the following problem:

then it means that not all the necessary jar files are available: either not packaged in the plugin download or they are missing from the plugin.xml.

Do the following (this particular solution worked for me, this or a similar one should also work for you):

1. Download the following jar files:

stax-api-1.0.1.jar
backport-util-concurrent-3.1.jar

and save them to eclipse/plugins/[Axis2 Codegen Wizard]/lib (replace [Axis2 Codegen Wizard] with the real plugin directory).

2. Add to the eclipse/plugins/[Axis2 Codegen Wizard]/plugin.xml the followings (to the <runtime> element), if they are missing:

<library name="lib/stax-api-1.0.1.jar">
<export name="*"/>
</library>

<library name="lib/backport-util-concurrent-3.1.jar">
<export name="*"/>
</library>

3. Restart Eclipse:

eclipse -clean

If you still have problems, then open eclipse/plugins/[Axis2 Codegen Wizard]/plugin.xml, and figure out which jar files are still missing. Use http://findjar.com/ for download locations of the missing files.

Links discussing the same problem:

Developing Web Services Using Apache Axis2 Eclipse Plugins

Blogs from Iterox - used this method to track down the problem

Headache gone after a solution in this blog? Then if you think... ;)

Wow, I am a top Google Gadget developer now...

2007-02-06T16:45:00.000+01:00

I don't know why, but I am among the "top" Google gadget developers, at the moment of writing, my rank is 71 (out of 80). It was just that simple password generator (available form my web page...), that brought me the Title and Sentences:

"These talented individuals are leading the charge in making your Google homepage a better place, and we think they deserve a standing ovation!"

Should I be finally proud of myself? :)))

It's here.

Internet Explorer problem with Google Gadgets

2006-12-21T16:30:00.000+01:00

I tried to add Google gadgets to my public home page (http://www.zsoltmolnar.hu). With Firefox and IE 7.0, it worked perfectly, however IE 6.0 was a disaster. It seems that IE6.0 cannot render more Google gadgets into table cells. Without tables, it works well. I strongly believe that it is an IE bug.

New Google gadget to generate safe passwords

2006-12-14T16:00:00.001+01:00

I've created a new google gadget, passwdgen for generating safe passwords. Available from here.

It is not a new stuff, I just "gadgetized" the service found here. The javascript code is reused as is.

I also hate passwords. I would like to use the "same" password everywhere, but it is not that safe method. The service generates a password, by mixing a master password and an optional string (best is the site where the password is submitted). You must not give out the master password, and it must be safe enough. You do not have to remember your passwords, because you can regenerate them any time.

Certainly, if your master password gets compromised, all your password may be revealed, but anyhow, it is much safer way that giving the same password everywhere.

Headache gone after a solution in this blog? Then if you think... ;)

"Symbolic link not allowed or link target not accessible..."

2006-07-03T23:17:00.001+02:00

Apache 2 refused to serve pages with that claim in the error_log (Suse 10.1). I had tried everything (permissions, ownership, etc.) - nothing worked. My httpd.conf piece looked really perfect:

<Directory "/srv/www/htdocs">
                Options FollowSymlinks
                AllowOverride None
                Order allow,deny
                Allow from all
</Directory>

and no success. Then, I found the line in the httpd.conf:

Include /etc/apache2/default-server.conf

Yes, yes, that include file contained a configuration for the document root, and certainly overwrote my settings. So, if your settings look really good, and the symlink problem still exists - look for such an include.

The problem seems to be obvious - but search Google for it, and you may be surprised...

Headache gone after a solution in this blog? Then if you think... ;)

Cannot renew ip address xp...

2006-06-18T14:12:00.001+02:00

Quite nasty a problem, happened to WinXP time to time. Last time, the VNC client stopped responding with a "socket error". Then everything went down, one after the other. Geez virus, or something similar animal... The always-cure reboot finalized the problem. XP said that the network card had limited connectivity, and tried to renew the IP address when I clicked on repair (had also tried ipconfig /release & renew without results) and it just told me it was unable to renew the IP address (which begun with 169.***.***.***).

The forums and groups did not give any usable tips, then finally I found this article: How to determine and recover from Winsock2 corruption.

The article is from Microsoft. I applied the suggested brutal-looking solution of typing netsh winsock reset at the command prompt. The article suggested that some of the winsock-sensitive apps would require a reinstall, but it looked a good compromise to reinstalling the whole Windows (having been customized for more than a year.)

After the reboot, it came back. Some of the applications looked dizzy a bit, but they recovered finally. Now I am happy again. Ah yes... the root of the problem must have been winsock2 corruption :)

Headache gone after a solution in this blog? Then if you think... ;)

Shared calendar

2006-03-18T17:53:00.000+01:00

I got fed up with the fact that my calendar content is distributed between several Exchange and web based calendar services, and maintaining the sync between them is quite a time consuming task. So, I set up a centralized calendar service by using WebDAV, iCalendar and Mozilla Calendar. My method was:

1. As I run a private Debian Linux/Apache 1.3 web server, I chose the mod_dav method. Downloaded the mod_dav sources. In order to compile, the apache-dev package must have been present:

apt-get install apache-dev

Then, the

configure --with-apxs

command worked.

2. Followed the info in the INSTALL file. The httpd.conf addition that worked for me was:

LoadModule dav_module /usr/lib/apache/1.3/libdav.so
AddModule mod_dav.c
DAVLockDB /tmp/DAVLock

...

mod_alias.c />.....
Alias /dav /home/httpd/dav

/dav /> AuthType Basic
AuthName "WebDAV"
AuthUserFile /> DAV on
AllowOverride None
Options None
GET HEAD OPTIONS /> Require user /> /> />.....

3. Then, set up the Mozilla Calendar by the info here.

Voila, I have a centrally stored calendar. I will set up "several" clients bound to the stored calendar file, one for my office, and a web interface for remote access when travelling. My calendar integrity is ensured, and I won't not miss a birthday any more :)