Saturday, September 28, 2013

Useful tricks for a new Linux environment for your applications

Hi guys!

Today I will give some simple devices that can save many hours of research and it might be hard to find out if you are not very familiar with configuring a new Linux server like RHEL (Red Hat Enterprise Linux)(for example, 6.x). People from development that just installed a RHEL instance to do some test might get stuck on this and say  "I can't access my service but it is running! How can this be possible?!".

Well my friends, here you need to checkout if it isn't your Firewall in your Linux. In most of distributions (also known as "distros") there are "iptables" installed. I will give some more details if your case are iptables, but the idea of the instructions is very generic, so you could apply in different Firewalls as well.

You can use "iptables -L" to make iptables to print its rules persisted so far.  You can edit the rules, but to make it simple as the use case for some test/development environment, let's just clean all the rules using " iptables -F". You might also want to turn it off, and in the last version of RHEL it would be "chkconfig iptables off".

You can also get others problems in your way, like SELinux (which is a very advanced and complex system for grant permissions to files in Linux). If you want to just turn it off, you can simply run "setenforce 0". Talking about RHEL, you might want to register your subscription, that is very easy now (if you don't subscribe you will not be able to access latest version of the packages). To register, you can follow the guide below:

This system is not yet registered. Try 'subscription-manager register --help' for more information.
subscription-manager register
Username: rhn-support-lcestari
Password:
The system has been registered with id: 096197b2-0a2c-4a42-b5ec-c23207a04c8c
subscription-manager attach --auto
Installed Product Current Status:
Product Name:         Red Hat Enterprise Linux Server
Status:               Subscribed

This will probably be enough to resgister into Red Hat. There is also some cool stuff that you might need (for example for Fuse) below:

yum install java-1.7.0-openjdk-devel.x86_64 unzip zip wget telnet


Thank you for reading, hope you find some useful informations. Best regards

Luan Cestari

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