Nextelco:Application Server

= Application Server =

The application server is a combination of different services which are necessary for the management of user accounts and devices which provide connectivity to end-users. This are the services offered by the application server:
 * AAA server: provides end-users and devices Authentication, Authorization and Accounting.
 * Billing server:
 * DHCP server: provides different range IP addresses depending on the requesting device.
 * DNS server: provides easy to remember names for devices which compose the service network. Specially interesting for device management and maintenance.
 * Web server: this service will provide the necessary interface to deal with the voucher system.
 * DB server: data base service is necessary to keep all accounting information in a centralized place and access it whatever the service we are using to manage users.
 * Management server: composed by Network Management System (NMS) for Radio Access Network (RAN) and RCMS for Base Station (BS) view and configuration.
 * Maintenance server: different and necessary services for network maintenance such as TFTP, SYSLOG, Time service (NTP), Speed test and File sharing.

The Application Server could be one or a combination of several physical servers. Each server could hold just one machine or a combination of different virtual machines. This will be decided depending on physical servers availability as well as their resources.

System installation
The application server has the following hardware characteristics:
 * Intel Xeon 3.2GHz x 4
 * 4GB RAM
 * Three network interfaces
 * Two Ethernet copper
 * One fiber
 * Two 36GB identical hard drives

Regarding the software, it is based on Debian GNU/Linux 7.5 (wheezy) distribution. Due to fact that the server has two equal hard drives, during Debian installation software based RAID1 has been set up. These are the partitions:
 * 1 -> 100MB /boot
 * 2 -> 8 GB swap
 * 3 -> Rest /



The configuration of RAID1 has been done according to this web page RAID on debian. However there are more useful web pages: After Debian installation it is important to set up GRUB on both hard drives. To do that this is the command that has been used: Additionally, if we want to check RAID status we use this command:
 * Setting up RAID
 * GRUB on RAID
 * 1) dpkg-reconfigure -plow grub-pc
 * 1) cat /proc/mdstat

It is convenient to install a SSH server in order to access the server remotely for any reason. These are the steps followed to install the SSH server:  Install openssh-server together with blacklisted RSA and DSA keys It is convenient to set up shared keys based log in. This increases the security level together with the deny of root login and password-based authentication.   Generate in the local machine a RSA key pair. $ssh-keygen -t rsa Copy on the server the generated public key. $scp path_to_RSA_key username@server:/home/username/.ssh/authorized_keys Edit openssh-server configuration -- change -- to AuthorizedKeysFile  %h/.ssh/authorized_keys -- change: #PasswordAuthentication yes -- to PasswordAuthentication no -- change PermitRootLogin yes -- to PermitRootLogin no Restart sshd server  In order to access the server through SSH this is the necessary command.</li> $ssh -i path_to_id_rsa(private) username@server </ol>
 * 1) apt-get install openssh-server openssh-blacklist openssh-blacklist-extra
 * 1) vi /etc/ssh/sshd_config
 * 1) AuthorizedKeysFile %h/.ssh/authorized_keys
 * 1) invoke-rc.d ssh restart

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