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Checking if a port is open using /dev directory

An old but useful tip. You don’t need telnet, nc or other related tool to check if a port is open.

Lets assume you want to check if the port 22 is open at host, perform it:

# echo > /dev/tcp/

Check the return code of the command above

# echo $?

If “0”, port is open, if “1” the port is closed.

That’s all.

; )


mod_fcgid: can’t apply process slot

Suddenly two web servers stopped to work, all networking connectivity was fine, I was able to connect their http port(80), but strange messages was being logged in /var/log/httpd/error.log:

[Sun Mar 25 10:28:18 2012] [warn] mod_fcgid: can’t apply process slot for /var/www/cgi-bin/php.fcgi

[Sun Mar 25 10:28:18 2012] [warn] mod_fcgid: can’t apply process slot for /var/www/cgi-bin/php.fcgi
[Sun Mar 25 10:28:18 2012] [warn] mod_fcgid: can’t apply process slot for /var/www/cgi-bin/php.fcgi
[Sun Mar 25 10:28:18 2012] [warn] mod_fcgid: can’t apply process slot for /var/www/cgi-bin/php.fcgi
[Sun Mar 25 10:28:18 2012] [warn] mod_fcgid: can’t apply process slot for /var/www/cgi-bin/php.fcgi

Searching a bit, I found that could be permissions errors, in fact it was the problem, a simple chmod 755 /var/log/httpd solved all problem.

What is your favorite Linux distribution for use on the desktop?


Let’s vote to Fedora


Click on following link and vote:

Enabling Nginx TLS SNI support on CentOS 5

By default centos 5.5 has openssl-0.9.8e which is not have tls extention for sni support. this is workaround on how to get nginx rpm with TLS SNI enabled

1 – Download SRPM of Nginx and openssl tarball
# wget
# wget

2 – Extract openssl in /usr/local/src and install SRPM
# tar -xzvf -C /usr/local/src
# rpm -ivh nginx-0.8.53-1.el5.src.rpm

3 – Edit nginx.spec (/usr/src/redhat/SPECS/nginx.spec) and add the following lines:
./configure \
–user=%{nginx_user} \
–group=%{nginx_group} \
–prefix=%{nginx_datadir} \
–sbin-path=%{_sbindir}/%{name} \
–conf-path=%{nginx_confdir}/%{name}.conf \
–error-log-path=%{nginx_logdir}/error.log \
–http-log-path=%{nginx_logdir}/access.log \
–http-client-body-temp-path=%{nginx_home_tmp}/client_body \
–http-proxy-temp-path=%{nginx_home_tmp}/proxy \
–http-fastcgi-temp-path=%{nginx_home_tmp}/fastcgi \
–pid-path=%{_localstatedir}/run/%{name}.pid \
–lock-path=%{_localstatedir}/lock/subsys/%{name} \
–with-openssl=”/usr/local/src/openssl-0.9.8l/” \
–with-openssl-opt=”enable-tlsext” \

–with-http_secure_link_module \
–with-http_random_index_module \
–with-http_ssl_module \
–with-http_realip_module \
–with-http_addition_module \
–with-http_sub_module \
–with-http_dav_module \

below change the following line:

make %{?_smp_mflags}



4 – Rebuild the RPM

# rpmbuild -bb nginx.spec

5 – Install and verify the new Nginx
# nginx -V
nginx version: nginx/0.8.53built by gcc 4.1.2 20080704 (Red Hat 4.1.2-48)
TLS SNI support enabled



Fedora 15 codename – I voted

The vote is on! If you are a Fedora Contributor, go to our voting system and vote on the next codename of Fedora!

The choices you have are:


Google Chrome Linux Stable?

After see many times updates for google-chrome as beta (google-chrome-beta) today I’d saw it as stable.

KDE Releases Development Platform, Applications and Plasma Workspaces 4.5.0

KDE today celebrates its semi-annual release event, making available new releases of the Plasma Desktop and Netbook workspacesthe KDE Development Platform and a large number of applications available in their 4.5.0 versions.

In this release, the KDE team focused on stability and completeness of the Desktop experience. More than 16,000 bugs have been fixed, and many feature requests have been filled. The result for the user is a system that feels faster, takes less time to “think”, and works more reliably. The large number of bug fixes goes accompanied with many parts that have got an extra portion of tender loving care. Plasma 4.5.0‘s new notification system is one example here. It is designed to get less in your way, yet to support your workflow as smoothly as possible. Visually, the striking monochromatic icons make for a more consistent look in the notification area. A highlight of the KDE Applications 4.5.0 is surely Marble, which can now be used for map routing as well as viewing. The Konqueror web browser can now also use the WebKit engine to render its content. The KDE Development Platform 4.5.0 offers a new generic cache for applications that need high-speed access to certain data, such as icons or other pre-rendered artwork. The new KSharedDataCache speeds up loading of many components, while the new HTTP scheduler is optimized for concurrent access to web servers, and makes loading of pages in Konqueror and other parts using the KIO HTTP mechanism faster.

Today’s releases are the first in the 4.5 series and will be followed with updated versions approximately monthly that will focus on fixing bugs. The next feature releases are planned for January 2011. If you would like to test-drive 4.5.0, you can do so by installing the packages that should be made available by your operating system vendor. You can also choose to build 4.5.0 from source, the nitty-gritty of that can be found on TechBase. For the impatient, there is also a Live CD available.

Source:KDE news

Finding out your IP address by DNS querying

A little trick to find out your outgoing IP address through a DNS query:

iarlyy@wolfman $ dig +short

This is it!… Happy Linuxing!

Tools for performance monitoring on Linux

For each single thing on Linux has a tool to monitor their performance, below a few:

top – process activity
vmstat – system activity, hardware and system information
uptime – average of system load
ps,pstree – list process
free – memory usage
iostat – average of CPU, disk activity
sar – collect and report system activity
mpstat – multiprocessor usage
pmap – process memory usage
netstat – network statistics
iptraf – real time network statistics
tcpdump – network traffic monitoring
strace – system calls
dstat – Versatile resource statistics
htop – process viewer for Linux, similar to top

Thanks to Scott Baker and Andy Burns for remember me dstat and htop.
Happy hacking!

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Fedora 13, Rock it =)