Skip to main content

Bind Master-Slave setup on CentOS 7.5

In this article I'm going to set up a master-slave DNS-Server cluster with bind on CentOS 7.5.

Some key data for this setup:
Master-Server IP-Address: 172.31.0.1
Slave-Server IP-Address:    172.31.0.2
Network:                                172.31.0.0/24


Master-Configuration

First install the necessary software.
 [root@ns01 ~]# yum -y install bind bind-utils
OPTIONAL! Create a rndc-key if you want to make updates dynamic:
 [root@ns01 ~]# rndc-confgen -a -b 512 -r /dev/urandom  
 chown root:named /etc/rndc.key  
 chmod 640 /etc/rndc.key
I usually create a directory for the log files and data files (zones) for bind.
 [root@ns01 ~]# mkdir /var/log/named  
 [root@ns01 ~]# chown -R named:named /var/log/named  
 [root@ns01 ~]# mkdir /var/named/data  
 [root@ns01 ~]# chown -R named:named /var/named/data
Edit the Master's /etc/named.conf file. In my case, the named.conf looks like this:
 [root@ns01 ~]# vim /etc/named.conf  

 //  
 // 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.  
 //  
 // See the BIND Administrator's Reference Manual (ARM) for details about the  
 // configuration located in /usr/share/doc/bind-{version}/Bv9ARM.html  
 include "/etc/named.rfc1912.zones";  
 include "/etc/named.root.key";  
 include "/etc/rndc.key";  
 controls {  
     inet 127.0.0.1 port 953 allow { 127.0.0.1; } keys { "rndc-key"; };  
 };  
 acl "trusted" {  
     127.0.0.1;  
     172.31.0.0/24;   
 };  
 options {  
     listen-on port 53 { 127.0.0.1; 172.31.0.1; };  
     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";  
     version none;  
     hostname none;  
     server-id none;  
     /*  
      - 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;  
     allow-recursion { trusted; };  
     allow-query { localhost; trusted; };  
     allow-transfer { localhost; 172.31.0.2; };  
     forward only;  
     forwarders {  
         195.46.39.40;  
         195.46.39.39;  
         };  
     auth-nxdomain no;  
     notify no;  
     dnssec-enable yes;  
     dnssec-validation no;  
     /* 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 "common_log" {  
         file "/var/log/named/named.log" versions 10 size 10m;  
         severity dynamic;  
         print-category yes;  
         print-severity yes;  
         print-time yes;  
     };  
     category default { "common_log"; };  
     category general { "common_log"; };  
     category queries { "common_log"; };  
     category client { "common_log"; };  
     category security { "common_log"; };  
     category query-errors { "common_log"; };  
     category lame-servers { null; };  
 };  
 zone "." IN {  
     type hint;  
     file "named.ca";  
 };  
 zone "archyslife.lan" {  
     type master;  
     file "data/db.archyslife.lan.zone";  
     notify yes;  
 };  
 zone "0.31.172.in-addr.arpa" {  
     type master;  
     file "data/db.0.31.172.in-addr.arpa.zone";  
     notify yes;  
 };
Now create the zone-files for the forward-zone of your network:
 [root@ns01 ~]# vim /var/named/data/db.archyslife.lan.zone  

 $TTL 86400                   ; 1 Day  
 @           IN SOA ns01.archyslife.lan. ns02.archyslife.lan. (  
                 2018062615   ; Serial  
                 3600         ; Refresh (1 Hour)  
                 3600         ; Retry (1 Hour)  
                 604800       ; Expire (1 Week)  
                 3600         ; Minimum (1 Hour)  
 )  
 @           NS   ns01.archyslife.lan.  
 @           NS   ns02.archyslife.lan.  
 ; A Records  
 @           A    172.31.0.1  
 @           A    172.31.0.2  
 ns01        A    172.31.0.1  
 ns02        A    172.31.0.2  
 ldap01      A    172.31.0.5  
 ldap02      A    172.31.0.10  
 ansible     A    172.31.0.6  
 ; SRV Records  
 _ldap._tcp   IN   SRV   0    100   389   ldap01.archyslife.lan.  
 _ldap._tcp   IN   SRV   0    100   389   ldap02.archyslife.lan.
And the reverse-zone for your network:
 [root@ns01 ~]# vim /var/named/data/db.0.31.172.in-addr.arpa.zone  

 $TTL 86400  
 @        IN SOA ns01.archyslife.lan. ns02.archyslife.lan. (  
                     2018062616   ; Serial  
                     3600      ; Refresh (1 Hour)  
                     3600      ; Retry (1 Hour)  
                     604800     ; Expire (1 Week)  
                     3600      ; Minimum (1 Hour)  
 )  
 @        NS    ns01.archyslife.lan.  
 @        NS    ns02.archyslife.lan.  
 ns01     A     172.31.0.1  
 ns02     A     172.31.0.2  
 1        PTR   ns01.archyslife.lan.  
 2        PTR   ns02.archyslife.lan.  
 5        PTR   ldap01.archyslife.lan.  
 10       PTR   ldap02.archyslife.lan.  
 6        PTR   ansible.archyslife.lan.
Set the appropriate SELinux-Contexts for your zone-files:
 [root@ns01 ~]# semanage fcontext -a -t named_zone_t /var/named/data/db.archyslife.lan.zone  
 [root@ns01 ~]# semanage fcontext -a -t named_zone_t /var/named/data/db.0.31.172.in-addr.arpa.zone  
 [root@ns01 ~]# restorecon -Rv /var/named  
 [root@ns01 ~]# setsebool -P named_write_master_zones 1
Restart and enable the named.service
 [root@ns01 ~]# systemctl restart named.service  
 [root@ns01 ~]# systemctl enable named.service
Allow named to communicate through the firewall
 [root@ns01 ~]# firewall-cmd --add-port={53/tcp,53/udp,953/tcp,953/udp} --permanent  
 [root@ns01 ~]# firewall-cmd --reload
Slave-Configuration

 First install the necessary software.
 [root@ns01 ~]# yum -y install bind bind-utils
Edit the Slave's /etc/named.conf file. In my case, it looks like this:
 [root@ns02 ~]# vim /etc/named.conf  

 //  
 // 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.  
 //  
 // See the BIND Administrator's Reference Manual (ARM) for details about the  
 // configuration located in /usr/share/doc/bind-{version}/Bv9ARM.html  
 include "/etc/named.rfc1912.zones";  
 include "/etc/named.root.key";  
 acl "trusted" {  
     127.0.0.1;  
     172.31.0.0/24;  
 };  
 options {  
     listen-on port 53 { 127.0.0.1; 172.31.0.2; };  
     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";  
     version none;  
     hostname none;  
     server-id none;  
     /*  
      - 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;  
     allow-recursion { trusted; };  
     allow-query { localhost; trusted; };  
     allow-transfer { none; };  
     auth-nxdomain no;  
     notify no;  
     dnssec-enable yes;  
     dnssec-validation no;  
     /* 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 "common_log" {  
         file "/var/log/named/named.log" versions 10 size 10m;  
         severity dynamic;  
         print-category yes;  
         print-severity yes;  
         print-time yes;  
     };  
     category default { "common_log"; };  
     category general { "common_log"; };  
     category queries { "common_log"; };  
     category client { "common_log"; };  
     category security { "common_log"; };  
     category query-errors { "common_log"; };  
     category lame-servers { null; };  
 };  
 zone "." IN {  
     type hint;  
     file "named.ca";  
 };  
 zone "archyslife.lan" {  
     type slave;  
     file "data/db.archyslife.lan.zone";  
     masters { 172.31.0.1; };  
     allow-notify { 172.31.0.2; };  
 };  
 zone "0.31.172.in-addr.arpa" {  
     type slave;  
     file "data/db.0.31.172.in-addr.arpa.zone";  
     masters { 172.31.0.1; };  
     allow-notify { 172.31.0.2; };  
 };
Allow named to write it's zones through SELinux:
 [root@ns02 ~]# setsebool -P named_write_master_zones=1
Restart and enable the named.service on the slave:
 [root@ns02 ~]# systemctl restart named.service  
 [root@ns02 ~]# systemctl enable named.service
Allow bind to communicate through the firewall
 [root@ns02 ~]# firewall-cmd --add-port={53/tcp,53/udp,953/tcp,953/udp} --permanent  
 [root@ns02 ~]# firewall-cmd --reload
Feel free to comment and / or suggest a topic.

Labels:

Comments

Post a Comment

Popular posts from this blog

Dynamic DNS with BIND and ISC-DHCP

I personally prefer to work with hostnames instead of ip-addresses. If you have anything like freeipa or active directory, it will do that for you by registering the client you added to your realm to the managed dns and edit the records dynamically. We can achieve the same goal with just bind and isc-dhcp. I'll use a raspberry pi with raspbian 9 for this setup. So here is a quick tutorial on how to configure the isc-dhcp-server to dynamically update bind. First set a static ip to your server. [archy@ddns ~]$ sudo vim /etc/network/interfaces # interfaces(5) file used by ifup(8) and ifdown(8) # Please note that this file is written to be used with dhcpcd # For static IP, consult /etc/dhcpcd.conf and 'man dhcpcd.conf' # Include files from /etc/network/interfaces.d: source-directory /etc/network/interfaces.d auto eth0 iface eth0 inet static address 172.31.30.5 network 172.31.30.0 broadcast 172.31.30.255 netmask 255.255.255.0 ...
Post a Comment
Read more

LACP-Teaming on CentOS 7 / RHEL 7

What is teaming? Teaming or LACP (802.3ad) is a technique used to bond together multiple interfaces to achieve higher combined bandwith. NOTE: every clients speed can only be as high as the single link speed of one of the members. That means, if the interfaces I use in the bond have 1 Gigabit, every client will only have a maximum speed of 1 Gigabit. The advantage of teaming is, that it can handle multiple connections with 1 Gigabit. How many connections depends on the amount of your network cards. I'm using 2 network cards for this team on my server. That means I can handle 2 Gigabit connections at full rate on my server provided the rest of the hardware can deliver that speed. There also exists 'Bonding' in the Linux world. They both do the same in theory but  for a detailed comparison check out this  article about teaming in RHEL7 . To create a teaming-interface, we will first have to remove all the interface configurations we've done on the (soon to be) sla...
8 comments
Read more

Push logs and data into elasticsearch - Part 2 Mikrotik Logs

This is only about the setup of different logging, one being done with Filebeat and the other being done with sending logging to a dedicated port opened in Logstash using the TCP / UDP Inputs. Prerequesites: You'll need a working Elasticsearch Cluster with Logstash and Kibana. Start by getting the Log Data you want to structure parsed correctly. Mikrotik Logs are a bit difficult since they show you Data in the interface which is already enriched with Time / Date. That means a message that the remote logging will send to Logstash will look like this: firewall,info forward: in:lan out:wan, src-mac aa:bb:cc:dd:ee:ff, proto UDP, 172.31.100.154:57061->109.164.113.231:443, len 76 You can check them in the grok debugger and create your own filters and mapping. The following is my example which might not fit your needs. Here are some custom patterns I wrote for my pattern matching: MIKROTIK_DATE \b(?:jan(?:uary)?|feb(?:ruary)?|mar(?:ch)?|apr(?:il)?|may|jun(?:e)?|jul(?...
9 comments
Read more

FreeIPA - Integrating your DHCPD dynamic Updates into IPA

I recently went over my network configuration and noticed that the dhcp-leases were not pushed into the IPA-DNS yet. So I thought, why not do it now. The setup is very similar to setting it up on a single bind instance not managed by IPA (I've already written a guide about this here ). My setup is done with the following hosts: ipa01.archyslife.lan - 172.31.0.1 inf01.archyslife.lan - 172.31.0.5 First of all, create a rndc-key: [archy@ipa01 ~]$ sudo rndc-confgen -a -b 512 This will create the following file '/etc/rndc-key' [archy@ipa01 ~]$ sudo cat /etc/rndc.key key "rndc-key" { algorithm hmac-md5; secret "secret_key_here=="; }; We also need to make named aware of the rndc-key and allow our remote dhcp server to write dns entries: [archy@ipa01 ~]$ sudo vim /etc/named.conf ... include "/etc/rndc-key"; controls { inet 172.31.0.1 port 953 allow { 172.31.0.5; } keys ...
2 comments
Read more

SSSD - Debugging PAM permission denied

Sometimes there's weird errors in IT that occur on random chance. I've had such an encounter with SSSD in combination with IPA(+AD-Trust) recently, where only sometimes, a connection to one of the IPA-Servers would fail with this error: Jul 13 13:36:42 ipa02.archyslife.lan sshd[3478]: pam_sss(sshd:account): Access denied for user runner: 4 (System error) Jul 13 13:36:42 ipa02.archyslife.lan sshd[3478]: fatal: Access denied for user runner by PAM account configuration [preauth] In my case, it was only happening sometimes when running a basic system setup role using ansible on every host in the entire environment. This way, there was no consistent pattern besides being the same host every time if it failed. First up, add the 'debug_level=X' to every section required in the /etc/sssd/sssd.conf where X is a number from 1 to 10 with 10 being the most verbose. Afterward, restart sssd and check the logs for any obvious problems. 1) If you are using local users, check the...
Post a Comment
Read more