January 8, 2016

Network Installation on Linux using NFS

Linux General,

The following package must be installed tftp , tftp server dhcp nfs Configure Dhcp Install dhcp,copy /usr/share/doc/dhcp-xxxx/dhcpd.conf.sample to /etc/dhcp/dhcpd.conf cp -r /usr/share/doc/dhcp-xxxx/dhcpd.conf.sample /etc/dhcp/dhcpd.conf vi dhcpd.conf option domain-name “your domain name”; option domain-name-servers YOUR-SERVER ; default-lease-time 600; max-lease-time 7200; allow bootp; allow booting; ignore client-updates; ddns-update-style none; not authoritative; log-facility local7; subnet YOUR-NETWORK netmask 255.255.255.0 {…

Read more
September 23, 2015

Open VPN Server Configuration on Linux

Linux General,

Install Open VPN RPM. Dependencies openssl lzo pkcs11-helper Download openvpn-<version>.rpm , And install using this command rpm -ivh openvpn-<version>.rpm It will create folder under /etc/openvpn and /usr/share/doc/openvpn-2.1.1 cp -r /usr/share/doc/openvpn-<version>/easy-rsa /etc/openvpn cp -r /usr/share/doc/openvpn-<version>/sample-config-files/server.conf /etc/openvpn we have to copy the “easy-rsa” folder and “server.conf” file from /user/share/doc/openvpn-<version>… to…. /etc/openvpn Then go to /etc/openvpn cd /etc/openvpn…

Read more
September 12, 2015

Networking Concepts, in RHEL 7 or CENTOS7.

Linux General,

Let’s see the networking concepts, in RHEL 7 or CENTOS7. You should concentrate on these if servers upgrade: We usually edit the network configuration file in the older versions to manage IPs. under /etc/sysconfig/network-scripts/ In the new version no more editing is required. We can add, modify, delete the IPs using the tool called NMCLI…

Read more
August 26, 2015

Symbolic link hack and its prevention in cPanel based servers.

Linux General,

Symbolic link: Just like we use shortcut in windows based operating system. Symbolic link (symlink or soft link) is a shortcut like file in linux operating systems. In linux a normal user cannot access server main/root directory. So, they use this symlink option as a tool to hack/gain access to server main/root directory. User will…

Read more
August 14, 2015

DNS Configuration (Internal and External)

Linux General,

The following package must be installed : bind-9.8.2-0.17.rc1.el6_4.6.i686.rpm bind-chroot-9.8.2-0.17.rc1.el6_4.6.i686.rpm bind-utils-9.8.2-0.17.rc1.el6_4.6.i686.rpm bind-libs-9.8.2-0.17.rc1.el6_4.6.i686.rpm Install  DNS:     Install bind and bind-chroot package using bellow command rpm -ivh bind-9.8.2-0.17.rc1.el6_4.6.i686.rpm rpm -ivh bind-chroot-9.8.2-0.17.rc1.el6_4.6.i686.rpm rpm -ivh bind-utils-9.8.2-0.17.rc1.el6_4.6.i686.rpm rpm -ivh bind-libs-9.8.2-0.17.rc1.el6_4.6.i686.rpm Create DNS key using below format: % dnssec-keygen -a hmac-md5 -b 128 -n USER dhcpupdate Kdhcpupdate.+157+14638 This will create a 128bit…

Read more
July 13, 2015

Routing Basics

Network,

Routers in a network discover remote networks in two ways Statically configured routes Dynamic routing protocols By default routers knows only the directly connected networks represented by “C” Static Routing Static route are mainly used when routing from a particular network to a stub network. Stub networks are the networks that can be accessed through…

Read more
July 8, 2015

Routers Basics

Network,

ROUTERS: It is an internetworking component that connects networks at different geographical locations.It has Serial Port Auxillary Port Console Port AUI (Attachment Unit Interface) or Ethernet(which uses RJ45 port) Routers are of two types Fixed -fixed number of slots (series from 700 to 2500, exception 1750, 1751) Modular – Upgradable slots and ports (series from…

Read more
July 1, 2015

Networking Basics

Network,

What is a Network? A network is any collection of independent computers(devices) which are connected to one another to share files and peripherals such as printers, modems, tape drives. Every Network includes: At least two computer server or client work station Network Interface card(NIC) A connection medium(wired or wireless) Network Operating System software Protocols: Protocols…

Read more
June 18, 2015

Iperf

Linux General,

Iperf was developed by NLANR/DAST as a modern alternative for measuring maximum TCP and UDP bandwidth performance. Iperf allows the tuning of various parameters and UDP characteristics. Iperf reports bandwidth, delay jitter, datagram loss. Iperf is available also for Windows The quality of a link can be tested as follows: – Latency (response time or…

Read more
June 2, 2015

MySQLTuner-perl Script

Linux General,

MySQLTuner is a script written in Perl that allows you to review a MySQL installation quickly and make adjustments to increase performance and stability. The current configuration variables and status data is retrieved and presented in a brief format along with some basic performance suggestions. Compatibility: MySQL 3.23, 4.0, 4.1, 5.0, 5.1 (full support) MySQL…

Read more