############################################
# DNS (DOMAIN NAMING SYSTEM (or) SERVICE) #
############################################
????????
? GOAL ?
????????
--> Multi level domain architechture for "linux-library.com"
IP Details of the sites :
-------------------------
192.168.1.110 : linux-library.com dev1.linux-library.com
192.168.1.120 : asia.linux-library.com prod01.linux-library.com
192.168.1.121 : india.linux-library.com rnd01.linux-library.com
192.168.1.130 : us.linux-library.com cops01.linux-library.com
192.168.1.150 : aus.linux-library.com mfg01.linux-library.com
Notes:
------
Here one of the most important thing we need to know is if we are trying to look for the domain "linux-library.com" it
actually looks for "linux-library.com." The dot after "com" is know as the root. Even we are not typing this dot it will
automatically look for the domain along with the root means "." This dot is very important as this is the place where every
domain begins. As if we compare it with filesystem for understanding this is equal to the root filesystem "/".
************************
* TYPE OF NAME SERVERS *
************************
00. RESOLVING NAME SERVER
01. ROOT NAME SERVER
02. TLD (TOP LEVEL DOMAIN) NAME SERVER
Ex. .com, .org, .net, .edu, .in, etc.(In our case it is ".com")
03. AUTHORITATIVE NAME SERVERS
Ex. The word before the TLD. In our case "linux-library"
Before preparing a domain let us know one of the most important thing in DNS which is Record Types.
Below i am just mentioning only some Record Types which are used for me in this case.
!!!!!!!!!!!!!!!!!!!!
! RESOURCE RECORDS !
!!!!!!!!!!!!!!!!!!!!
TYPE : DESCRIPTION : FUNCTION
---------------------------------------------------------------------------------------------------
A : Address record : Returns a 32-bit IPv4 address, most commonly used to map hostnames to an IP
address of the host, but it is also used for DNSBLs, storing subnet masks in
RFC 1101, etc.
AAAA : IPv6 address record : Returns a 128-bit IPv6 address, most commonly used to map hostnames to an IP
address of the host.
CNAME : Canonical name record : Alias of one name to another: the DNS lookup will continue by retrying the
lookup with the new name.
MX : Mail exchange record : Maps a domain name to a list of message transfer agents for that domain
NS : Name server record : Delegates a DNS zone to use the given authoritative name servers
PTR : Pointer record : Pointer to a canonical name. Unlike a CNAME, DNS processing stops and just the
name is returned. The most common use is for implementing reverse DNS lookups,
but other uses include such things as DNS-SD.
SOA : Start of [a zone of] : Specifies authoritative information about a DNS zone, including the primary
authority record : name server, the email of the domain administrator, the domain serial number,
and several timers relating to refreshing the zone.
$$$$$$$$
$ TASK $
$$$$$$$$
@! : Assume we have a main parent domain "linux-library.com". Also we have some child domains in
"Asia, India, US, Australia"
$0 : Get your machine ready with all the packages needed.
$0.00 : Verify all the packages installed.
$1 : Create a the parent domain (linux-library.com) on "dev1", its zones both Forward(FWD) and Reverse(REV).
$1.01 : Verify and ensure that the parent domain resolution.
$2 : Create the child domain (asia.linux-library.com) on "prod1" with its zones both FWD & REV.
$2.01 : Verify and ensure that the above child domain resolution.
$3 : Create the child domain (india.linux-library.com) on "rnd1" with its zones both FWD & REV.
$3.01 : Verify and ensure that the above child domain resolution.
$4 : Create the child domain (us.linux-library.com) on "cops1" with its zones both FWD & REV.
$4.01 : Verify and ensure that the above child domain resolution.
$5 : Create the child domain (aus.linux-library.com) on "mfg1" with its zones both FWD & REV.
$5.01 : Verify and ensure that the above child domain resolution.
©©©©©©©©©©©©©©©©©©©©©©©©©©©©©
© $0 : Configuring packages ©
©©©©©©©©©©©©©©©©©©©©©©©©©©©©©
==================================================================================
$0. Let us install the packages which are necessary for DNS. Below are the required packages.
P1. bind-9.7.3-2.el6.i686
P2. bind-utils-9.7.3-2.el6.i686
P3. bind-dyndb-ldap-0.2.0-1.el6.i686
P4. bind-chroot-9.7.3-2.el6.i686
P5. bind-libs-9.7.3-2.el6.i686bind-libs
# yum install bind* -y
$0.00. Check whether the packages installed properly or not.
# rpm -qa | grep ^bind
==================================================================================
©©©©©©©©©©©©©©©©©©©©©©©©©©©©©©©©©
© $1 : Configure Parent Domain ©
©©©©©©©©©©©©©©©©©©©©©©©©©©©©©©©©©
==================================================================================
Let us configure our Parent Domain i.e., "linux-library.com" for our Task #1 ($1).
Below is the list of configs to do to complete $1.
©1. Copy the files which starts with "named" from /etc to /var/named/chroot/etc/
Next copy all the contents of /var/named to /var/named/chroot/var/named/
This is because i need to maintain all the config files in /var/named/chroot
to provide security from Hackers.
# cp -prv /etc/named* /var/named/chroot/etc/
# cd /var/named
# tar -cvf named.tar .
# mv named.tar /var/named/chroot/var/named/
# cd /var/named/chroot/var/named/
# tar -xvf named.tar
# rm -rf chroot
==================================================================================
©2. Edit /var/named/chroot/etc/named.conf (DNS Configuration main file) to add the IP of your parent domain and create a
zone with in the file contains details of the parent domain.
Go to the "options" section, locate the following lines
# vi /var/named/chroot/etc/named.conf
listen-on port 53 { 127.0.0.1; 192.168.1.110; }; ---> Provide the Parent domain "linux-library.com".
My IP is "192.168.1.110"
allow-query { any; }; ---> Replace localhost with any.
allow-transfer { 192.168.1.120; }; ---> Provide the IP of the slave machine
==================================================================================
©3. Edit /var/named/chroot/etc/named.rfc1912.zones and add the Forward and Reverse zones
Add a zone section as below which provides the details of the forward lookup zone file.
zone "linux-library.com" IN {
type master;
file "linux-library.com.forward.zone";
allow-update { none; };
};
Add a zone section as below which provides the details of the reverse lookup zone file.
zone "1.168.192.in-addr.arpa" IN {
type master;
file "linux-library.com.reverse.zone";
allow-update { none; };
};
==================================================================================
©4. Create forward lookup zone file and add the details of the parent domain.
Go to /var/named/chroot/var/named/ and make a copy of "named.localhost" to our forward lookup zone file
"linux-library.com.for.zone" and modify that as per our choice.
# cp -prv /var/named/chroot/var/named/named.localhost /var/named/chroot/var/named/linux-library.com.for.zone
# vi /var/named/chroot/var/named/linux-library.com.for.zone
$TTL 1D
@ IN SOA linux-library.com. root.linux-library.com. (
2016051801 ; serial
1D ; refresh
1H ; retry
1W ; expire
3H ) ; minimum
@ IN NS dev1.linux-library.com.
@ IN NS prod1.linux-library.com.
IN A 192.168.1.110
dev1 IN A 192.168.1.110
prod1 IN A 192.168.1.120
asia IN CNAME prod1.linux-library.com.
==================================================================================
©5. Create reverse lookup zone file and add the details of the parent domain.
Go to /var/named/chroot/var/named/ and make a copy of "named.loopback" to our forward lookup zone file
"linux-library.com.reverse.zone" and modify that as per our choice.
# cp -prv /var/named/chroot/var/named/named.loopback /var/named/chroot/var/named/linux-library.com.reverse.zone
# vi /var/named/chroot/var/named/linux-library.com.reverse.zone
$TTL 1D
@ IN SOA linux-library.com. root.linux-library.com. (
2015061801 ; serial
1D ; refresh
1H ; retry
1W ; expire
3H ) ; minimum
@ IN NS dev1.linux-library.com.
@ IN NS prod1.linux-library.com.
A 192.168.1.110
PTR linux-library.com.
110 IN PTR dev1.linux-library.com.
120 IN PTR prod1.linux-library.com.
asia IN CNAME prod1.linux-library.com.
==================================================================================
©©©©©©©©©©©©©©©©©©©©©©©©©©©©©©©©©©©©©©©©
© $2 : Configure Child (PROD1) Domain ©
©©©©©©©©©©©©©©©©©©©©©©©©©©©©©©©©©©©©©©©©
==================================================================================
©1. Get the config files ready. To do this please follow the steps provided in
$1.©1
==================================================================================
©2. Edit /var/named/chroot/etc/named.conf (DNS Configuration main file) to add the IP.
Go to the "options" section, locate the following lines
# vi /var/named/chroot/etc/named.conf
listen-on port 53 { 192.168.1.120; };
allow-query { any; };
==================================================================================
©3. Edit /var/named/chroot/etc/named.rfc1912.zones and add the Forward and Reverse zones
Add a zone section as below which provides the details of the forward lookup zone file.
zone "linux-library.com" IN {
type slave;
file "slaves/linux-library.com.forward.zone";
allow-update { none; };
};
Add a zone section as below which provides the details of the reverse lookup zone file.
zone "1.168.192.in-addr.arpa" IN {
type slave;
file "slaves/linux-library.com.reverse.zone";
allow-update { none; };
};
==================================================================================
©4. Keep in mind that no need of creating the zone files as the zone files will be
replicated from the server automatically.
==================================================================================
As like the configuration for PROD1 we can go ahead with the remaining configs.
----------------------------------------
Explanation of symbols used in this doc.
# - Main heading
? - Our goal
* - Important to know
! - Information for our reference
$ - Task to do
P - Package
© - Configuration Friday 24 June 2016
ELA_34_01_Managing_multiple_Domains_at_zone_level
Wednesday 22 June 2016
Version Control - 05.GitHub_Passwordless_Push
SSH keys to push your commits without asking for password:
While working with your repositories on GitHub you commit your changes locally. And once you feel you are good with the changes then you will push all the local commits to GitHub. But on thing which annoys you at this moment is it will ask for the password everytime.
So, in such cases you can use the SSH-RSA keys to push your changes with out being asked for password.
Below is the complete process of doing that.
| Step 1: Go to ".ssh" dir located in your homedir | |
| Generate an RSA key | |
| # ssh-keygen -t rsa | |
| Now you will have "id_rsa.pub" file. | |
| Copy the contents of it. | |
| Step 2: | |
| Login to your GitHub account | |
| Click on your account and then Click on the Settings button in the right most corner | |
| Select "SSH and GPG keys" | |
| Click on "New SSH Key" | |
| Paste the copied content of "id_rsa.pub" there. | |
| Step 3: | |
| Go to your repository on your host or VM | |
| Configure your Git URL | |
| git remote set-url origin git+ssh://<username>@github.com/<accountname>/<repo_name>.git | |
| You are all set now. Try to push your commits to the remote repo with out giving the password. |
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