Tag Archives: network

Finally a Linux jmx query tool that works out of the box!

I've tried many many jmx query tools from the command line, 
windows has the jconsole tool which is a part of the Java binaries pack, and works fine, 
but it is not a command line tool – it has a nice GUI. 

this command line jar works like a charm, 
displays all the beans it finds, and allows you to invoke them , 

take a look at :

http://crawler.archive.org/cmdline-jmxclient/

only the cmdline-jmxclient-0.10.3.jar files is available for some reason, 
searches in google didnt find the newer file at all. 

than you run it with :

java -jar cmdline-jmxclient.jar – SERVER:PORT

to get a listing of all the available beens.

more samples are available on the link above. 

works like a charm!

 

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Social Networking Map

social networking map

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?

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solaris 10 and vnc

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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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Linux Commands – Top 20 Most Used

Installing linux on ps3

The history file is a log file of your last used commands on the Linux server,
It can be found in your home directory and is called .bash_history (with the “.” in the start).
You can either read the file itself to see its content, or use the command history which will do the same thing.

When looking at my history files on my Linux servers,
I can see maybe 20 Linux commands which I keep using over and over,
They are the most important tools of my work, and I recommend learning them well to any starting Linux sysadmin.

Files and Directories Management

  • ls – Lists files and directories content, I usually use “ls -la” to have a long listing with all the details and hidden files
  • cd – move from the current directory to a different folder
  • pwd – lists your current location
  • mv – this command can either change the name of a file, or move it to a different location.
  • locate – find any file on the Linux server, to get an updated index of files (if for example you just installed a whole bunch of RPM’s) run the command updatedb
  • ln – create a shortcut to a file or folder
  • tar – create or extract files out of a storage file. with the correct arguments it will also compress the files

Editing and Viewing

  • tail – lists the last 10 lines of a file, but you tell tell it to show any number of last lines
  • vi – the best command line editing software :)  a little hard to learn how to work this one at first, buts its worth the effort
  • cat – list the content of the file. better know how long is the file you are running this command on, or you will get a very long scrolling of lines that will fill up your screen

A Very Good Linux Administration Book

Network

  • nslookup – very important networking tool – this will show you where a DNS name is pointing – to which IP or to another DNS
  • wget – get a file from the web from the command line – if you need to download some RPM directly to the command line without a browser, this is the command you need
  • ping – I think its one of the most used commands, you can check the time it takes you to get via the network to a remote server, whether that server is available, how many packets are getting to the server, etc

Installing linux on ps3

General

  • history – lists the last used commands on your Linux server
  • make – when compiling a software from source, this command will create the binaries
  • id – who am I right now? besides the philosophical angle, this command will show you as which user you will be running commands, I use this to check what is my status, and then sudo to the user I need
  • sudo – execute a command as another user – although  usually use it to change to root
  • ps – list the running processes on the server, it give more info like the process id, the parent process id, running time and much more
  • man – displays a manual page, whenever you are not sure about a specific command or config file, you should run “man command” to get info about it. to search the man database use “whatis command” to find which man file has the info you need
  • df – report file system disk space usage, use “df -h” to get a human formatted listing

Installing linux on ps3

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proxy settings for the command line

  

When using applications from the command line,
you will sometimes need to setup a specific proxy for them to use, if you don’t have a direct access to the Internet from the server you are working on.

in some of these application you can setup this through the app switches itself, but simpler apps just use the system network settings.

to fix this you can first check what current settings you have now with:

ENV | grep -i proxy

this should show you the current proxy settings you have.

to add your own settings do:

export http_proxy=”http://<proxy-server-ip>:<port>”
export ftp_proxy=”http://<proxy-server-ip>:<port>”

for example:

export http_proxy=”http://192.168.0.10:8080″

after that, just run your command line app, it should pick up and use these settings.

   

 

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