snowBlog

Linux and F1

2011-04-04T01:27:00.000-07:00

What is the relation between linux and formula one?. Adapted from various sources (please googling:), it mentioned that some current F1 teams have been using linux for purposes of computing systems R & D. Computing systems usually require calculation power generated by a collection of servers that form a cluster.
What is the use of this Linux cluster?, we sort one by one:

McLaren F1 Team
* Using Linux for CFD analysis (Computational Fluid Dynamics). CFD is a field of study involving the modeling of wind currents that pass through objects such as car racing. CFD software is a simulation software to determine and predict the behavior of racing cars in various scenarios of wind currents, so the team can develop the right aero package .
* CFD software provided by SGI and run on an SGI Altix supercomputer which of course use the linux OS.

Renault F1 Team
* Using Linux for analysing the results of telemetry posted on the engine and chassis during the race for later use in optimizing the ability of the machine.
* Telemeteri and database software run on IBM's Linux.

BMW Williams F1 Team
* This team also uses CFD software for design and testing aero package. The applications run on top of the HP XC Linux Cluster

Ferrari F1 Team
* This team uses a Linux cluster for R & D in engine and aerodynamic analysis. It also mentioned that Ferrari has collaborated with AMD and now has a Linux cluster with 500 nodes of server.

Restrict SSH access on linux

2008-11-04T19:22:00.000-08:00

Have you ever thought to restrict login access to a linux server for security reasons?
One way is to delete any accounts who do not require. But for some reason we can not delete the accounts, because it needed for authentication such as POP3/IMAP.

Well, there's one more way to limit logins without the need to remove users from the system, namely restricting ssh access. How do we do?. We need to edit the OpenSSH configuration file.

[root@snowy ~]# vim /etc/ssh/sshd_config

to allow only user1 and user2, add the the directive 'AllowUser', example

AllowUsers user1 user2

or allow group1 and group2:

AllowGroups group1 group2

to block user user1 and user2, use 'DenyUsers'L

DenyUsers user1 user2

or deny group1 and group2

DenyGroups group1 group2

Save the file and restart the SSHD, assuming we use RHEL or Fedora:

[root@snowy ~]# service sshd restart
Stopping sshd: [ OK ]
Starting sshd: [ OK ]

Try login after that.

Argument list too long

2008-11-03T23:02:00.000-08:00

Pernahkah mengalami hal seperti di bawah ini?:

[root@snowy clientmqueue]# rm -f *
-bash: /bin/rm: Argument list too long

Argument apa yg dimaksud?... oh ternyata perintah rm, mv ... dan lainnya (blum coba) punya batasan jumlah file yang bisa di handle. Perkiraan saya adalah 65535 (perlu dibuktikan).

Well, lupakan dulu itu, saya sedang diburu waktu karena file file ngga penting di /var/spool/clientmqueue ternyata menghabiskan space di /var dan bikin aplikasi laen tidak bisa nulis ke direktori itu misalkan syslog, php session etc.

Apa yang harus saya lakukan?. Insting saya mengatakan kita harus baca filenya satu persatu lalu menghapusnya. Ok let's do it (carefully!).

Ok kita coba testing dulu tanpa melakukan delete

cd /var/spool/clientmqueue/
ls -1|while read myfile; do echo $myfile; done

hasilnya:

[root@snowy clientmqueue]# ls -1|while read myfile; do echo $myfile; done
dfk21NE7J8006097
dfk22L2M7P012934
dfk23L27p3009736
dfk24L2KuP029846
dfk25L2Btp009903
dfk26L25hh025984
dfk27L27bF007017
dfk28L2633019792
^C

Sukses!!!.

ok kita tambahkan rm -f di perintah tadi:

[root@snowy clientmqueue]# ls -1|while read myfile;do echo $myfile;rm -f $myfile;done

Selesai!.

Create Yum Repositories

2008-10-28T01:24:00.000-07:00

YUM stands for Yellow Dog Updater, Modified is a tool used to handle package management linux distribution.
You may never have dependencies on other packages when you want to install an rpm package. You then have to install one by one package which may also have individual dependencies on other packages again. Well, here's where you need yum to work for you, simply type:

yum install

Voila, all dependencies resolved. Installation went smoothly with only a single command.
Well, suppose you have just installed a linux system with a minimalist package because of limited space or you want a slim server. Say you as a developer so you simply install the development packages, editor and http packets, and then decides to make Yum repositories at one another webserver to be able to add the package at a later time using Yum.
Langkah-langkah yang bisa anda lakukan untuk membuat Yum repositories:

- make a directory where the files will be saved rpm distribution. For example your web server's document root is / var / www / html:

cd /var/www/html
mkdir -p rhel5/Server

- copy the contents of the CD RHEL5 rpm

cp /mnt/cdrom/Server/*.rpm rhel5/Server

- download source application createrepo from http://createrepo.baseurl.org/download/, direct install:

rpm --rebuild createrepo-0.4.11-1.src.rpm
rpm -ivh /usr/src/redhat/RPMS/noarch/createrepo-0.4.11-1.noarch.rpm

- enter the directory / var/www/html/rhel5/Server and run createrepo

cd /var/www/html/rhel5/Server
createrepo .

- Yum repositories ready

Return to your new Linux system pre-installed, create the file /etc/yum.repos.d/RHEL-os.repo. Example configuration (adjust to your conditions):

[rhel-os]
name=Red Hat Enterprise Linux OS
baseurl=http://10.10.10.10/rhel5/Server/
enabled=1
gpgcheck=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-release

Good luck

Create self-signed Ceritificate

2007-05-01T04:03:00.000-07:00

It turned out pretty simple. See references to redhat at:
http://www.redhat.com/docs/manuals/linux/RHL-9-Manual/custom-guide/s1-secureserver-generatingkey.html

Or do the following:

/ usr / bin / openssl genrsa 1024> / etc / httpd / conf / ssl.key / server.key
chmod go-rwx / etc / httpd / conf / ssl.key / server.key

umask 77; \
/ usr / bin / openssl req-new-key / etc / httpd / conf / ssl.key / server.key-out / etc / httpd / conf / ssl.csr / server.csr

umask 77; \
/ usr / bin / openssl req-new-key / etc / httpd / conf / ssl.key / server.key-x509-days 365-out / etc / httpd / conf / ssl.crt / server.crt

That's it.