Category: Desktop

Okay let be clear: i dislike Dell’s iDRAC. Sure unlike ILO there is no license to buy and the interface is pretty convenient, but why something as essential as the console access is so buggy and unreliable ?

Last example: no matter which version of Java i use on my Arch direct crash of the console at startup. After digging a little I luckily came across this link which explain everything and give this workaround :

zapan:~# vi /tmp/idracfix.c
#define _GNU_SOURCE

#include 
#include 
#include 

void *dlopen(const char *filename, int flags) {
    if (filename && !strcmp(filename, "/usr/lib/libssl.so"))
            return NULL;
    void *(*original_dlopen)(const char *, int);
    original_dlopen = dlsym(RTLD_NEXT, "dlopen");
    return (*original_dlopen)(filename, flags);
}

Compile it:

gcc -Wall -fPIC -shared -o idracfix.so idracfix.c -ldl

And for now launch javaws while setting LD_PRELOAD when using iDrac console :

LD_PRELOAD=./idracfix.so javaws viewer.jnlp

Ranger

ranger is a console file manager with vi key bindings. It provides a minimalistic and nice curses interface with a view on the directory hierarchy (Miller column’s style).

Text files are displayed in a simple pager using less. Zipped files are automatically uncompressed and viewed in the same way. If you choose an image file, a preview will be displayed in colored ascii art.

Ranger uses many of the same keybindings as “vim”.
For instance, the movement commands mirror vim closely:

j = Move down
k = Move up
h = Move to parent directory
gg = Go to the top of the list
G = Go to the bottom of the list
-f = Page down
-b = Page up
J = Page down 1/2 page
K = Page up 1/2 page
H = Go back through navigation history
L = Go forward through navigation history

Last File Manager

If you prefer a more ‘traditional’ way of browsing, you can try lfm. It’s a powerful ncurse file manager written in Python. It support 1-pane or 2-pane views, tabs, files filters, bookmarks, history and VFS support for compressed files.

Midnight Commander

Midnight Commander is probably the most well-known application of this kind and probably the most easy to use due to being the closest to old and well know “Norton Commander”. In MC arrow keys control file selection, the insert key is used to select files and the Function Keys perform operations such as renaming, editing and copying files. It also supports mouse operations.

xdiskusage is a graphical tool for displaying disk usage per directory. It’s kind of an ancestor to the more desktop oriented tool baobab and filelight.

One terrific feature for sysadmin of xdiskusage is that it can use a du output file as data source !

First generate an output file on the host to analyse (here foobar-host1) :

# du -ab * > du_foobar-host1.txt

rsync the du output file on your desktop machine, then make a:

# xdiskusage du_foobar-host1.txt

Parallel SSH is a useful tool designed to run a command on multiple servers in parallel. An advantage of PSSH over some alternatives (like DSH) is the manner outputs are stored: all outputs are sent to a folder containing an output file per server.

Using PSSH

First create your servers list, using the syntax host:port user :

vi /tmp/hosts_list.txt
server1
server2
server3:2222 foobar

Then create two directories: one for standard outputs, the second for error outputs.

mkdir /tmp/output
mkdir /tmp/error

Then execute your command:

parallel-ssh -h /tmp/hosts_list.txt -o /tmp/output/ -e /tmp/error/ uptime

Further Reading and sources

• http://code.google.com/p/parallel-ssh
• man parallel-ssh

If you know the Windows program ‘ArtMoney’ you already have an idea what a memory scanner/editor like Scanmem could be used for.

For other people, basically this kind of tools allow you to search for variables in memory of a running process, generally using one initial value and then a second. When you have the precise offset, you can set the value as you wish (and then have a toon of money, lives or ammo).

This kind of tool could also be used to analyze an hostile process on a compromised machine but cheating in games is way more cool ^^

GNU Screen have a very useful feature: sharing the same same session with multiple terminals.

Setting up a shared screen session

The following command sequence sets up a shared screen session named ‘shared’:

screen -d -m -S shared

Listing screen sessions

screen -ls
There is a screen on:
	8632.shared	(Detached)
1 Socket in /var/run/screen/S-pkb.

Attaching an existing session

screen -x shared

Doing the same… with different users

First the bad news : screen sharing with another account requires that the screen command be suid root. That a strong security risk so do it only if you are on a non-critical environment. When it’s done, simply start a new session as usual, then:

Enable multiuser support

Ctrl-A
:multiuser on

Add the user to join your session

Ctrl-A
:acladd foobar

Now the user foobar can join the session shared launched by the user user like this screen -x user/shared.

By default rdesktop try to give you the best image quality which is fine on a LAN but inappropriate in other case. But using some options you can change this behaviour:

• -x disable theming
• -m disable mouse motion events
• -z to enable compression
• -r soundff disable sound
• -P enable bitmap caching

So now i use the following command:

rdesktop -u username -f -m -z -x m -P -r soundff -0 myip

In order to access to all DRAC features through an SSH Tunnel, you need to forward ports TCP 443, 5900 and 5901:

# sudo ssh -L 443:10.10.22.167:443 -L 5900:10.10.22.167:5900 -L 5901:10.10.22.167:5901 root@foobar_vm.foo.fr