what is JMX?

JMX is a technology that lets you add management interfaces for Java applications

the jmx interface on your java application will let you monitor and publish graphs for:

• heap memory
• threads and their stack trace
• CPU
• classes
• memory pools

Enabling JMX in Tomcat

wrapper.java.additional.1=-Dcom.sun.management.jmxremote

wrapper.java.additional.2=-Dcom.sun.management.jmxremote.port=<port>

wrapper.java.additional.3=-Dcom.sun.management.jmxremote.ssl=false

wrapper.java.additional.4=-Dcom.sun.management.jmxremote.authenticate=false

wrapper.java.additional.5=-Djava.rmi.server.hostname=<ServerName>

Things to verify before usage:

1. the numbers after the “wrapper.java.additional.” part are in increasing order – make sure to continue from where the last config line showed, and make sure there are no gaps in the counting.
2. change <port> to the port number you wish to expose
3. these settings will enable password-less connection to you JMX server, if you wish to add authentication and SSL you will need to change these settings.
4.  change <ServerName> to your server name – this setting is needed – without it the server will only allow localhost connections and wont allow remote.

  

Technorati Tags: java, jmx, tomcat

This is a nice bit from Larry Ellison the CEO of Oracle,
He talks about Cloud Computing term as a new name for the same internet everyone has used for years.

Wiki calls it:

The term “cloud” is used as a metaphor for the Internet, based on the cloud drawing used in the past to represent the telephone network, and later to depict the Internet in computer network diagrams as an abstraction of the underlying infrastructure it represents.

He objects to the absurdity of the term cloud – since it is the same server-based service that was always there and is connected to the internet – the same OS, service, Database etc…

I agree heartily with him – ever since anyone of us joined the first web-based email service or web hosting,
we all have used the cloud.

What do you think?
do we have now a different cloud computing then we had ever since the internet started working?
Please post your thoughts in the comments …

Technorati Tags: Cloud Computing, Internet, interviews, Solaris

This Link will lead you to this social-networking-map in full size,
which is a lovely Data Visualization which i love,
you can see in this post here about Management Data Visualization all kind of samples of Management related Data Visualization images.

The issue I want to raise here besides my appreciation for the designing of this concept,
Is the fact I didn’t find ICQ in there.

Now I have a special place in my heart for ICQ,
and since they still have many millions of users, I think they should have ben represented in this image,
But all I could find there are some “receding glaciers of AOL” and “AIM Tundra”.

I think ICQ was the Origin of the internet socializing idea, and some kind of a relic at least should be in it,
although ICQ is still alive and kicking, and in the process of changing ownership – ICQ Sold to the Russians.

So, My question for the day is:

Can you Find ICQ in the picture, Boys and Girls?

Technorati Tags: funny, network, Social Network

I’m always searching for better tools to do my work,
and today I have found this nice DNS online testing tool made with Ajax,
It’s quite nice and fast, and its good when you do not have a Linux distro at hand,
or have a problem with whois test from a proxied server.

The site offers:

• Live DNS test
• whois search
• IP whois
• HTTP headers

and more tools like it, very handy tool and works fast.

I do appreciate it when someone thinks of the GUI also and not just the functions in a tool.

Technorati Tags: DNS, Online Tools

Network File System (NFS) is a network file system protocol originally developed by Sun Microsystems in 1984, allowing a user on a client computer to access files over a network in a manner similar to how local storage is accessed.

So basically its a network share, it allows you to share files between remote computers
in the most easy and seamless way, once it was specifically for UNIX servers,
but today NFS is supported over MS servers as well.

Like everything else in Sysadmin life,
when its working its working well, and nobody hears about it,
but what to do when its not working?
Samba debugging for example is easier from that aspect since it has extensive logs for the sysadmin,
NFS doesn’t keep logs, and NFS issues doesn’t show up in the syslog/messages file as well.

But there are tools that allow you to get extensive information about the running NFS process,
shares, statistics, users connected etc :

Technorati Tags: Command line, NFS, samba, Solaris

VNC is a server client method of connecting to a remote server,
the great thing about vnc is that you can see the remote server desktop, and work on it with a mouse just like its your local desktop.
another good thing about vnc is that its free for use for many distros.

There are main 2 major software companies that supply free vnc server and vnc cllient,
the first is realvnc and the second is tightvnc , from the tighvnc site:

TightVNC is a free remote control software package. With TightVNC, you can see the desktop of a remote machine and control it with your local mouse and keyboard, just like you would do it sitting in the front of that computer. TightVNC is:

• free for both personal and commercial usage, with full source code available (GPL-licensed);
• useful in remote administration, remote customer support, education, and for many other purposes;
• cross-platform, available for Windows and Unix, compatible with other VNC software.

So these are 2 options for you to download a good free vnc viewer.

Solaris VNCserver configuration

and I say only viewer because now the Solaris 10 build 5 comes with the vncserver alredy inside.
all you need to do is to configure it.

This page on the SUN site will give you the detailed explanation on how to do things and what security patch you need to install fisrt ,but the instructions can be summed up in 4 lines:

mkdir -p /etc/dt/config

cp /usr/dt/config/Xservers    /etc/dt/config/Xservers

edit this file “/etc/dt/config/Xservers” and add these lines at the end:

:1  Local local_uid@none root /usr/X11/bin/Xvnc :1 -nobanner -AlwaysShared -SecurityTypes None -geometry 1024x768x24 -depth 24
:2  Local local_uid@none root /usr/X11/bin/Xvnc :2 -nobanner -AlwaysShared -SecurityTypes None -geometry 1024x768x24 -depth 24
:3  Local local_uid@none root /usr/X11/bin/Xvnc :3 -nobanner -AlwaysShared -SecurityTypes None -geometry 1024x768x24 -depth 24
And reboot the server.

The lines with the :1 :2 etc at the beginning, are the virtual displays you wish to server to have available for connections, you can add more by changing the numbers to :4 :5 etc.

when connecting to the server with the vnc viewer you need to express to which virtual display you want to connect by adding it to end of the server’s name or ip:

10.10.10.1:3

If you want to connect to virtual display number 3.

A security note – this configuration will allow passwordless access to the vnc screen – if someone logs in and leaves it open – the next user can just enter without a login.

A safer configuration is to require a password by using the -SecurityTypes VncAuth parameter. The Xvnc(1) man page describes password requirements.

VNC and Security

The vnc as a general is clear text, for a more secure connection there is a method of tunneling the vnc through a ssh session.
2 nice tutorials for vnc through ssh can be found here and here.
the second tutorial is using putty for the ssh connection – putty is another great freeware,
its a free ssh client for windows to connect to ssh servers.

If the server you wish to connect to through vnc is located withing your lan,
and you are relaxed about security for the users on it – if its a training server etc ,
you can just setup the vncserver without any safeguards,
but if you are connecting through an unsecured medium (AKA the internet)
you better add the ssh layer to it.

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Each With The Click of a Button!

Technorati Tags: desktop, Linux, network, Solaris, windows

Well I sometimes bite too so here is the latest Linux links list I have fallen for:
15 Power tools for Linux that you cant afford to miss,
I havent checked all the links in the page yet, but I will.

And you should probably check out the whole blog,
It looks very promising and fun to read.
from their description:
Penguin Inside is a blog about Linux and Software Guides, How-TOs, Reviews.
The blog is dedicated to Linux Desktops.

Another Good list is from Smashing Magazine:
50 Beautiful Flash Websites , and thats a beutiful list of 50 stunning flash websites,
A couple that i liked the most are:

e-Content Solutions

and v5 Design

Technorati Tags: Command line, desktop, Hardware, Linux

So you went ahead and did a little change to your web site, or web server redirect,
and you want to test it out without a sniffer,
the fastest way to test the http server headers and output is from the command line so you can see exactly what the servers is sending.

Now from Linux you have built in tools like GET, and wget ad curl,
wget and curl you can also install on windows to work from the command line.

Curl For Windows

Go ahead and download curl from their main website, you should get the Win32 – General version,
or the Win64 binary.
Better take the SSL enabled version if you will ever need to test SSL.
Take the curl.exe file from the zip file and place it somewhere in your windows PATH.

To find which directories are already in the windows path open the command line and write:

C:\>echo %PATH%

You will get the listing for such directories, just place the curl.exe in one of them.

Now for the tests:
To get only the headers and not the file contents itself use “curl -I http://address”

C:\>curl -I http://some.site.com/blocked_folder/blocked.php
HTTP/1.0 403 Forbidden
Server: Apache
Accept-Ranges: bytes
Content-Type: text/html
Expires: Tue, 27 Oct 2009 19:32:38 GMT
Cache-Control: max-age=0, no-cache, no-store
Pragma: no-cache
Date: Tue, 27 Oct 2009 19:32:38 GMT
Connection: keep-alive

From this test you can see the file is forbidden, what are the caching setings for the server, and other headers information.

If you would like to see the full page contents just remove the “-I”.

another sample:

C:\>curl -I http://www.cisco.com/
HTTP/1.1 200 OK
Date: Tue, 27 Oct 2009 19:36:28 GMT
Server: Apache/2.2
Set-Cookie: CP_GUTC=62.214.121.218.123463458258569; path=/; expires=Sat, 21-Oct-34 19:36:28 GMT; domain=.cisco.com
Last-Modified: Tue, 27 Oct 2009 16:34:14 GMT
ETag: “5985″
Accept-Ranges: bytes
Content-Length: 22917
CDCHOST: cdcxweb-prod1-02
Content-Type: text/html

this time we got a 200 reply which means the apache sent us the page,
we can see the page’s size from the “Content-Length” header,
and the other info the apache wants to send us.

Testing for Virtual hosts

Virtual hosting on apache can mean having more domain names on the same IP,
and you can test each of these domains by adding a “Host” header to the curl test line:

curl -H “Host: sub1.host.com” http://www.hosting.com/
curl -H “Host: sub2.host.com” http://www.hosting.com/

These 2 lines will bring back the html code for each of the different virtual hosts on the same server.

Here are some more ideas of using curl -for example:
Sending POST data through curl

Technorati Tags: apache, Command line, Linux, windows