Thursday, March 26, 2015

View systemd information

VIEW systemd INFORMATION

This is for redhat 7 

systemctl list-dependencies
Show a unit’s dependencies
systemctl list-sockets
List sockets and what activates
systemctl list-jobs
View active systemd jobs
systemctl list-unit-files
See unit files and their states
systemctl list-units
Show if units are loaded/active
systemctl get-default
List default target (like run level)

Tuesday, March 24, 2015

Setting Up DNS Server On CentOS 7



DNS Server Installation
Scenario
For the purpose of this tutorial, I will be using three nodes. One will be acting as Master DNS server, the second system will be acting as Secondary DNS, and the third will be our DNS client. Here are my three systems details.

Primary (Master) DNS Server Details:
Operating System     : CentOS 7 minimal server
Hostname             : masterdns.goldenjohn.local
IP Address           : 192.168.1.101/24

Secondary (Slave) DNS Server Details:
Operating System     : CentOS 7 minimal server
Hostname             : secondarydns.goldenjohn.local
IP Address           : 192.168.1.102/24

Client Details:
Operating System     : CentOS 6.5 Desktop  
Hostname             : client.goldenjohn.local
IP Address           : 192.168.1.103/24



Setup Primary (Master) DNS Server
Install bind9 packages on your server.
yum install bind bind-utils -y

1. Configure DNS Server

Edit ‘/etc/named.conf’ file.
vi /etc/named.conf



Add the lines as shown in bold:
//
// named.conf
//
// Provided by Red Hat bind package to configure the ISC BIND named(8) DNS
// server as a caching only nameserver (as a localhost DNS resolver only).
//
// See /usr/share/doc/bind*/sample/ for example named configuration files.
//

options {
    listen-on port 53 { 127.0.0.1; 192.168.1.101;}; ### Master DNS IP ###
#    listen-on-v6 port 53 { ::1; };
    directory     "/var/named";
    dump-file     "/var/named/data/cache_dump.db";
    statistics-file "/var/named/data/named_stats.txt";
    memstatistics-file "/var/named/data/named_mem_stats.txt";
    allow-query     { localhost; 192.168.1.0/24;}; ### IP Range ###
    allow-transfer{ localhost; 192.168.1.102; };   ### Slave DNS IP ###

    /*
     - If you are building an AUTHORITATIVE DNS server, do NOT enable recursion.
     - If you are building a RECURSIVE (caching) DNS server, you need to enable
       recursion.
     - If your recursive DNS server has a public IP address, you MUST enable access
       control to limit queries to your legitimate users. Failing to do so will
       cause your server to become part of large scale DNS amplification
       attacks. Implementing BCP38 within your network would greatly
       reduce such attack surface
    */
    recursion yes;

    dnssec-enable yes;
    dnssec-validation yes;
    dnssec-lookaside auto;

    /* Path to ISC DLV key */
    bindkeys-file "/etc/named.iscdlv.key";

    managed-keys-directory "/var/named/dynamic";

    pid-file "/run/named/named.pid";
    session-keyfile "/run/named/session.key";
};

logging {
        channel default_debug {
                file "data/named.run";
                severity dynamic;
        };
};

zone "." IN {
    type hint;
    file "named.ca";
};

zone "goldenjohn.local" IN {
type master;
file "forward.goldenjohn";
allow-update { none; };
};
zone "1.168.192.in-addr.arpa" IN {
type master;
file "reverse.goldenjohn";
allow-update { none; };
};

include "/etc/named.rfc1912.zones";
include "/etc/named.root.key";







2. Create Zone files
Create forward and reverse zone files which we mentioned in the ‘/etc/named.conf’ file.
2.1 Create Forward Zone
Create forward.goldenjohn file in the ‘/var/named’ directory.
vi /var/named/forward.goldenjohn
Add the following lines:
$TTL 86400
@   IN  SOA     masterdns.goldenjohn.local. root.goldenjohn.local. (
        2011071001  ;Serial
        3600        ;Refresh
        1800        ;Retry
        604800      ;Expire
        86400       ;Minimum TTL
)
@       IN  NS          masterdns.goldenjohn.local.
@       IN  NS          secondarydns.goldenjohn.local.
@       IN  A           192.168.1.101
@       IN  A           192.168.1.102
@       IN  A           192.168.1.103
masterdns       IN  A   192.168.1.101
secondarydns    IN  A   192.168.1.102
client          IN  A   192.168.1.103






2.2 Create Reverse Zone
Create reverse.goldenjohn file in the ‘/var/named’ directory.
vi /var/named/reverse.goldenjohn
Add the following lines:
$TTL 86400
@   IN  SOA     masterdns.goldenjohn.local. root.goldenjohn.local. (
        2011071001  ;Serial
        3600        ;Refresh
        1800        ;Retry
        604800      ;Expire
        86400       ;Minimum TTL
)
@       IN  NS          masterdns.goldenjohn.local.
@       IN  NS          secondarydns.goldenjohn.local.
@       IN  PTR         goldenjohn.local.
masterdns       IN  A   192.168.1.101
secondarydns    IN  A   192.168.1.102
client          IN  A   192.168.1.103
101     IN  PTR         masterdns.goldenjohn.local.
102     IN  PTR         secondarydns.goldenjohn.local.
103     IN  PTR         client.goldenjohn.local.


3. Start the DNS service
Enable and start DNS service:
systemctl enable named
systemctl start named



4. Firewall Configuration
We must allow the DNS service default port 53 through firewall.
firewall-cmd --permanent --add-port=53/tcp



5. Restart Firewall
firewall-cmd --reload


6. Configuring Permissions, Ownership, and SELinux
Run the following commands one by one:
chgrp named -R /var/named
chown -v root:named /etc/named.conf
restorecon -rv /var/named
restorecon /etc/named.conf



7. Test DNS configuration and zone files for any syntax errors
Check DNS default configuration file:
named-checkconf /etc/named.conf
If it returns nothing, your configuration file is valid.
Check Forward zone:
named-checkzone goldenjohn.local /var/named/forward.goldenjohn
Sample output:
zone goldenjohn.local/IN: loaded serial 2011071001
OK
Check reverse zone:
named-checkzone goldenjohn.local /var/named/reverse.goldenjohn 
Sample Output:
zone goldenjohn.local/IN: loaded serial 2011071001
OK
Add the DNS Server details in your network interface config file.
vi /etc/sysconfig/network-scripts/ifcfg-enp0s3
TYPE="Ethernet"
BOOTPROTO="none"
DEFROUTE="yes"
IPV4_FAILURE_FATAL="no"
IPV6INIT="yes"
IPV6_AUTOCONF="yes"
IPV6_DEFROUTE="yes"
IPV6_FAILURE_FATAL="no"
NAME="enp0s3"
UUID="5d0428b3-6af2-4f6b-9fe3-4250cd839efa"
ONBOOT="yes"
HWADDR="08:00:27:19:68:73"
IPADDR0="192.168.1.101"
PREFIX0="24"
GATEWAY0="192.168.1.1"
DNS="192.168.1.101"
IPV6_PEERDNS="yes"
IPV6_PEERROUTES="yes"
Edit file /etc/resolv.conf,
vi /etc/resolv.conf
Add the name server ip address:
nameserver      192.168.1.101
Save and close the file.
Restart network service:
systemctl restart network


8. Test DNS Server
dig masterdns.goldenjohn.local
Sample Output:
; <<>> DiG 9.9.4-RedHat-9.9.4-14.el7 <<>> masterdns.goldenjohn.local
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 25179
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 2

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;masterdns.goldenjohn.local.    IN    A

;; ANSWER SECTION:
masterdns.goldenjohn.local. 86400    IN    A    192.168.1.101

;; AUTHORITY SECTION:
goldenjohn.local.        86400    IN    NS    secondarydns.goldenjohn.local.
goldenjohn.local.        86400    IN    NS    masterdns.goldenjohn.local.

;; ADDITIONAL SECTION:
secondarydns.goldenjohn.local. 86400 IN    A    192.168.1.102

;; Query time: 0 msec
;; SERVER: 192.168.1.101#53(192.168.1.101)
;; WHEN: Wed Aug 20 16:20:46 IST 2014
;; MSG SIZE  rcvd: 125
nslookup goldenjohn.local
Sample Output:
Server:        192.168.1.101
Address:    192.168.1.101#53

Name:    goldenjohn.local
Address: 192.168.1.103
Name:    goldenjohn.local
Address: 192.168.1.101
Name:    goldenjohn.local
Address: 192.168.1.102
Now the Primary DNS server is ready to use.
It is time to configure our Secondary DNS server.



Setup Secondary(Slave) DNS Server

Install bind packages using the following command:
yum install bind bind-utils -y

1. Configure Slave DNS Server
Edit file ‘/etc/named.conf’:
vi /etc/named.conf
Make the changes as shown in bold.
//
// named.conf
//
// Provided by Red Hat bind package to configure the ISC BIND named(8) DNS
// server as a caching only nameserver (as a localhost DNS resolver only).
//
// See /usr/share/doc/bind*/sample/ for example named configuration files.
//
options {
listen-on port 53 { 127.0.0.1; 192.168.1.102; };
listen-on-v6 port 53 { ::1; };
directory "/var/named";
dump-file "/var/named/data/cache_dump.db";
        statistics-file "/var/named/data/named_stats.txt";
        memstatistics-file "/var/named/data/named_mem_stats.txt";
allow-query     { localhost; 192.168.1.0/24; };
.
.
.
.
zone "." IN {
type hint;
file "named.ca";
};
zone "goldenjohn.local" IN {
type slave;
file "slaves/goldenjohn.fwd";
masters { 192.168.1.101; };
};
zone "1.168.192.in-addr.arpa" IN {
type slave;
file "slaves/goldenjohn.rev";
masters { 192.168.1.101; };
};
include "/etc/named.rfc1912.zones";
include "/etc/named.root.key";


2. Start the DNS Service
systemctl enable named
systemctl start named
Now the forward and reverse zones are automatically replicated from Master DNS server to ‘/var/named/slaves/’ in Secondary DNS server.
ls /var/named/slaves/
Sample Output:
goldenjohn.fwd  goldenjohn.rev

3. Add the DNS Server details
Add the DNS Server details in your network interface config file.
vi /etc/sysconfig/network-scripts/ifcfg-enp0s3
TYPE="Ethernet"
BOOTPROTO="none"
DEFROUTE="yes"
IPV4_FAILURE_FATAL="no"
IPV6INIT="yes"
IPV6_AUTOCONF="yes"
IPV6_DEFROUTE="yes"
IPV6_FAILURE_FATAL="no"
NAME="enp0s3"
UUID="5d0428b3-6af2-4f6b-9fe3-4250cd839efa"
ONBOOT="yes"
HWADDR="08:00:27:19:68:73"
IPADDR0="192.168.1.102"
PREFIX0="24"
GATEWAY0="192.168.1.1"
DNS1="192.168.1.101"
DNS2="192.168.1.102"
IPV6_PEERDNS="yes"
IPV6_PEERROUTES="yes"
Edit file /etc/resolv.conf,
vi /etc/resolv.conf
Add the name server ip address:
nameserver      192.168.1.101
nameserver      192.168.1.102
Save and close the file.
Restart network service:
systemctl restart network


4. Firewall Configuration
We must allow the DNS service default port 53 through firewall.
firewall-cmd --permanent --add-port=53/tcp

5. Restart Firewall
firewall-cmd --reload

6. Configuring Permissions, Ownership, and SELinux
chgrp named -R /var/named
chown -v root:named /etc/named.conf
restorecon -rv /var/named
restorecon /etc/named.conf

7. Test DNS Server
dig masterdns.goldenjohn.local
Sample Output:
; <<>> DiG 9.9.4-RedHat-9.9.4-14.el7 <<>> masterdns.goldenjohn.local
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 18204
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 2

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;masterdns.goldenjohn.local.    IN    A

;; ANSWER SECTION:
masterdns.goldenjohn.local. 86400    IN    A    192.168.1.101

;; AUTHORITY SECTION:
goldenjohn.local.        86400    IN    NS    masterdns.goldenjohn.local.
goldenjohn.local.        86400    IN    NS    secondarydns.goldenjohn.local.

;; ADDITIONAL SECTION:
secondarydns.goldenjohn.local. 86400 IN    A    192.168.1.102

;; Query time: 0 msec
;; SERVER: 192.168.1.102#53(192.168.1.102)
;; WHEN: Wed Aug 20 17:04:30 IST 2014
;; MSG SIZE  rcvd: 125
dig secondarydns.goldenjohn.local
Sample Output:
; <<>> DiG 9.9.4-RedHat-9.9.4-14.el7 <<>> secondarydns.goldenjohn.local
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 60819
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 2

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;secondarydns.goldenjohn.local.    IN    A

;; ANSWER SECTION:
secondarydns.goldenjohn.local. 86400 IN    A    192.168.1.102

;; AUTHORITY SECTION:
goldenjohn.local.        86400    IN    NS    masterdns.goldenjohn.local.
goldenjohn.local.        86400    IN    NS    secondarydns.goldenjohn.local.

;; ADDITIONAL SECTION:
masterdns.goldenjohn.local. 86400    IN    A    192.168.1.101

;; Query time: 0 msec
;; SERVER: 192.168.1.102#53(192.168.1.102)
;; WHEN: Wed Aug 20 17:05:50 IST 2014
;; MSG SIZE  rcvd: 125
nslookup goldenjohn.local
Sample Output:
Server:        192.168.1.102
Address:    192.168.1.102#53

Name:    goldenjohn.local
Address: 192.168.1.101
Name:    goldenjohn.local
Address: 192.168.1.103
Name:    goldenjohn.local
Address: 192.168.1.102


Client Side Configuration
Add the DNS server details in ‘/etc/resolv.conf’ file in all client systems
vi /etc/resolv.conf
# Generated by NetworkManager
search goldenjohn.local
nameserver 192.168.1.101
nameserver 192.168.1.102
Restart network service or reboot the system.




Test DNS Server
Now, you can test the DNS server using any one of the following commands:
dig masterdns.goldenjohn.local
dig secondarydns.goldenjohn.local
dig client.goldenjohn.local
nslookup goldenjohn.local
That’s all about now. The primary and secondary DNS servers are ready to use.
Cheers!