DNS缓存服务器是一种不负责域名数据维护的DNS服务器。简单来说，缓存服务器就是把用户经常使用到的域名与IP地址的解析记录保存在主机本地，从而提升下次解析的效率，这次使用unbound这款软件部署缓存服务器
一、 准备工作
1、 实验拓扑
| 节点 | IP地址 | 说明 |
|---|---|---|
| DNS-server | 192.168.0.100 | 缓存服务器 |
| centos2 | 192.168.0.101 | 客户端 |
2、 unbound软件介绍
Unbound是红帽公司（RedHat）默认使用的的DNS服务包,Unbound是一个安全性高、功能强大、配置简单。
3、 使用参数说明
| 参数 | 说明 |
|---|---|
| interface | 监听ip |
| interface-automatic | 如果部署在非默认端口上，例如80/443，则需要禁用此选项 |
| access-control | 允许网段 |
| forward-zone | 允许域名，从哪里缓存 |
二、 ansible文件
1、 目录结构
[root@mmx_ansible dns_automating_unbound]# ls ansible.cfg inventory.yml server.conf.j2 unbound.conf unbound.yml
2、 配置文件
ansible.cfg
[defaults] inventory=./inventory.yml remote_user=root
3、主机清单文件
inventory.yml
home：
caching_dns:
ansible_host: 192.168.0.100
ansible_ssh_password: "密码"
ansible_user: "用户名"
4、 模板文件
server.conf.j2
{# 通过列举出所有的ipv4地址，来写 #}
server:
{% for ip in ansible_facts['all_ipv4_addresses'] %}
interface: {{ ip }}
{% endfor %}
interface-automatic: no
access-control: {{ access_control }}
domain-insecure: {{ domain_insecure }}
forward-zone:
name: "{{ forward_zone_name }}"
forward-addr: {{ forward_addr }}
5、 playbook
unbound.yml
--- - name: ubound is deployed on caching nameservers hosts: caching_dns become: yes vars: forward_addr: "114.114.114.114" access_control: "0.0.0.0/0 allow" domain_insecure: "*" forward_zone_name: "." tasks: - name: unbound is installed(安装软件包) yum: name: unbound state: present - name: unbound configuration is correct(配置unbound文件，当修改该文件时，重启服务) template: src: server.conf.j2 dest: /etc/unbound/conf.d/server.conf owner: root group: unbound mode: '0644' setype: named_conf_t notify: - restart unbound - name: unbound is started and enabled(开启&&开机启动unbound服务) service: name: unbound state: started enabled: yes - name: unbound is started and enabled(确保防火墙开启) service: name: firewalld state: started enabled: yes - name: dns is enabled on the firewalld(放行unbound服务) ansible.posix.firewalld: service: dns state: enabled permanent: yes immediate: yes handlers: # 重启unbound服务 - name: restart unbound service: name: unbound state: restarted
6、 执行playbook
ansible-playbook unbound.yml
[root@mmx_ansible dns_automating_unbound]# ansible-playbook unbound.yml PLAY [ubound is deployed on caching nameservers] ************************************************************************************************************************************************************************************************* TASK [Gathering Facts] *************************************************************************************************************************************************************************************************************************** ok: [caching_dns] TASK [unbound is installed(安装软件包)] ********************************************************************************************************************************************************************************************************** ok: [caching_dns] TASK [unbound configuration is correct(配置unbound文件，当修改该文件时，重启服务)] *************************************************************************************************************************************************************** ok: [caching_dns] TASK [unbound is started and enabled(开启&&开机启动unbound服务)] ********************************************************************************************************************************************************************************* ok: [caching_dns] TASK [unbound is started and enabled(开启&&开机启动unbound服务)] ********************************************************************************************************************************************************************************* ok: [caching_dns] TASK [dns is enabled on the firewalld(放行unbound服务)] ****************************************************************************************************************************************************************************************** ok: [caching_dns] PLAY RECAP *************************************************************************************************************************************************************************************************************************************** caching_dns : ok=6 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
三、测试
1、 客户端
1） 临时修改客户端DNS地址
[root@dns_client ~]# vim /etc/resolv.conf nameserver 192.168.0.100
2） nslookup访问百度
[root@dns_client ~]# nslookup www.baidu.com Server: 192.168.0.100 Address: 192.168.0.100#53 Non-authoritative answer: www.baidu.com canonical name = www.a.shifen.com. Name: www.a.shifen.com Address: 182.61.200.7 Name: www.a.shifen.com Address: 182.61.200.6
2、 缓存服务器
1 ) 查看修改的配置文件
[root@DNS-Server_ubound ~]# cat /etc/unbound/conf.d/server.conf server: interface: 192.168.0.100 interface-automatic: no access-control: 0.0.0.0/0 allow domain-insecure: * forward-zone: name: "." forward-addr: 114.114.114.114
2）查看缓存
unbound-control dump_cache
[root@DNS-Server_ubound ~]# unbound-control dump_cache START_RRSET_CACHE ;rrset 155 1 0 2 3 a.shifen.com. 155 IN SOA ns1.a.shifen.com. baidu_dns_master.baidu.com. 2301200016 5 5 2592000 3600 ;rrset 125 2 0 5 3 www.a.shifen.com. 125 IN A 182.61.200.6 www.a.shifen.com. 125 IN A 182.61.200.7 ;rrset 545 1 0 5 3 www.baidu.com. 545 IN CNAME www.a.shifen.com. END_RRSET_CACHE START_MSG_CACHE msg www.a.shifen.com. IN AAAA 33152 1 155 3 0 1 0 a.shifen.com. IN SOA 4 msg www.baidu.com. IN A 33152 1 125 3 2 0 0 www.baidu.com. IN CNAME 0 www.a.shifen.com. IN A 0 msg www.a.shifen.com. IN A 33152 1 125 0 1 0 0 www.a.shifen.com. IN A 0 END_MSG_CACHE EOF
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