Famous SELinux Contexts

1. httpd SELinux context

                                        chcon -v --type=httpd_sys_content_t /path/to/dir

2.httpd SELinux context

                   chcon -Rv --type=httpd_sys_content_t /path/to/dir

3. Restore old/default context

                   restorecon -Rv -n /var/www/html


                    ;  -n switch to prevent any relabelling occurring.
4. Changing default port for services permitted SELinux

                                     #  semanage port -l
                    # semanage port -a -t http_port_t -p tcp 81
5. For Nagios

chcon -R -t httpd_sys_content_t /usr/local/nagios

        

  1st command to see what are the supported services. 2nd one changing default port for http service.



Note: Give me time to write them with proper explanation. 

More: http://wiki.centos.org/TipsAndTricks/SelinuxBooleans

Process Management

Hello , My new blogpost is about Process Management and I have gone all concepts of Process Management. I have written this document with help of .Doc and it consists of images. So its hard to maintain the format in blogger too. I am placing the download link , Please use that link to download. I hope it helps you. To Download my post Please click here

Install & configure SSH in CentOS 6.X

Today I am going to start writing an article about SSH installation and configuration in CentOS. SSH means Secure Shell. When ever we are doing any kind of remote transmission though telnet,It will transmit the information as clear text and anybody is in the network can see whats being transferred and username/password and other sensitive information which supposed to be very secure.So to protect remote data operations SSH invented.
For Information : http://en.wikipedia.org/wiki/Secure_Shell
--------------------- How to install SSH ----------------------
Open your terminal and type

yum install openssh-server openssh-clients

After installing it , we have to make it as autostart with system boot. to make it so execute below command
chkconfig sshd on
To start,stop,restart and to know status of service

service sshd start
service sshd stop
service sshd restart
service sshd status

-----------------------------------------------------------------
Now we have to configure SSH.
------------------------------------------------------------------
Main purpose of SSH is remote host access , so to accept remote incoming connections we must allow the port in IPTables. So add the below line IPTables

vim /etc/sysconfig/iptables
-A INPUT -m state --state NEW -m tcp -p tcp --dport 22 -j ACCEPT

Then restart IPTables

service iptables restart

---------------------------------------------------------------------
GIVE ME TIME TO UPDATE IT

FTP in CentOS 6.x with vsftpd,ftp.

In this tutorial I am going to explain about how to install and configure FTP server with Vsftpd and ftp.

To install

yum install vsftpd ftp

Do

setsebool -P ftp_home_dir=1

for SELinux.


after installing edit the configuration file with

vim /etc/vsftpd/vsftpd.conf

For basic secured FTP these are the necessary actions you should follow.

Disable Anonymous login If you want with placing

anonymous_enable=NO

or comment #anonymous_enable=YES.

If you want to restrict users to their home directory Then uncomment

chroot_local_users=YES

For most of the times we generally consider FTP users home directory as their directory. But we can add custom directory location if you want.

syntax:

useradd -d /path/path <username>

ex:

useradd -d /ftp/raja rajapasswd raja

so right now raja user we use to login into FTP and its in a custom directory.

If you want to add vsftpd service as autostart from next restart then you better add it startup list with

chkconfig --levels 235 vsftpd on

there 2,3,5 are runlevels

If you want to start FTP service i.e vsftpd then

service vsftpd start

in the same way restart ,stop,status are as follow

service vsftpd restart service vsftpd stop service vsftpd status

Sometimes we may need to store the local server log time in your log of FTP , so write this line at the end of the configuration file I have mentioned above

use_localtime=YES

Now due to security reasons no one will use default FTP port 21 as their port for service. We can change it.
Open the configuration file of vsftpd and mention at line as

listen_port=2121

or anyportyouwant

then save and close it.

after that restart vsftpd service. But you wont be able to connect . why means here you have changed default port, so automatically you have to update the same port in your IPTables.

open IPtables with

vim /etc/sysconfig/iptables

and write a line like

-A INPUT -p tcp -m state --state NEW -m tcp --dport 2121 -j ACCEPT

Then restart iptables with

service iptables restart

so It will now accepts remote FTP connections through that port.


Here you have to add Boolean to selinux to get allow from it. I have set selinux to permissive from enforcing with

setenforce 0

then check with

getenforce

Now I am going to tell you about how to share single FTP directory for multiple users.

This is pretty simple I am introducing ACL's here. Many people do in their own way and this is mine.

add user first with

useradd -d /ftp/raja raja2

then

setfacl -m u:raja2:rwx /ftp/raja

so for users Raja and Raja2 we are giving same directory for sharing.

How to login ?

If you ware using default port of FTP i.e 21 then assume like your FTP server IP as 192.168.1.1

then in terminal like

ftp 192.168.1.1

then give username and password.

make sure you have followed selinux thing before this to have proper connectivity.

If you have changed default port , the way of connecting will be different a little but , assume your new port is 4545 then you can connect with

ftp 192.168.1.1 4545

Let me give time to arrange this post with proper format.
But I am sure , It is clear enough to read and let me know If I am missing anything I will add it.