Category 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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Adding JMX support to your java app

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
and it will also expose the java Mbeans tree which you can browse
with the jconsole app included with any java distribution:
you can either browse and read these attributes,
and in some cases edit them and change the application status.

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Oracle CEO Larry Ellison makes fun of “Cloud Computing”

httpv://www.youtube.com/watch?v=UOEFXaWHppE&feature=share

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… Continue reading Oracle CEO Larry Ellison makes fun of “Cloud Computing”

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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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NFS mount – When Your Shares Go Wrong

From Wikipedia:

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 :

Description

Command

see what the machine is exporting SunOS: # exportfs
Solaris: # share
Print the list of shared file systems showmount -e server_name
Print the list of all clients mounting a directory from the questioned server showmount -a server_name
Print the directory and all the clients that are mounting it curretly – from within the nfs server dfmounts
print the nfs netwrok statistics client side: nfsstat -c
server side: nfsstat -s
To see that nfsd is responding rpcinfo -T udp crimson nfs
To see that mountd is responding rpcinfo -T udp crimson mountd
To see that lockd is responding rpcinfo -T udp crimson nlockmgr

rpcinfo -T udp crimson llockmgr

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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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I Like Good Linux Lists On The Morning

Lists are the magic word for SEO and link bait, and they catch the eye.

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

econtent

and v5 Design

v5design_s

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