写在前面
- 使用过滤器检查、验证和操作包含网络信息的变量
- 理解不足小伙伴帮忙指正
傍晚时分，你坐在屋檐下，看着天慢慢地黑下去，心里寂寞而凄凉，感到自己的生命被剥夺了。当时我是个年轻人，但我害怕这样生活下去，衰老下去。在我看来，这是比死亡更可怕的事。--------王小波
收集和处理网络信息
标准 setup 模块可在多个 play 开头自动收集事实，从每个受管主机上收集大量与网络相关的信息。
常用的网络事实：
- ansible_facts[‘dns’][‘nameservers’]
- ansible_facts[‘domain’]
- ansible_facts[‘all_ipv4_addresses’]
- ansible_facts[‘all_ipv6_addresses’]
- ansible_facts[‘fqdn’]
- ansible_facts[‘hostname’]
查看所有清单主机的完全限定名
---
- name: net_work
hosts: all
tasks:
- name: print
debug:
msg: "{
{ ansible_facts['fqdn'] }}"
$
执行测试
$ ansible-playbook network.yaml
.........
TASK [print] ***************************************************************************************************************
ok: [servera] => {
"msg": "servera.lab.example.com"
}
ok: [serverb] => {
"msg": "serverb.lab.example.com"
}
ok: [serverc] => {
"msg": "serverc.lab.example.com"
}
ok: [serverd] => {
"msg": "serverd.lab.example.com"
}
ok: [servere] => {
"msg": "servere.lab.example.com"
}
ok: [serverf] => {
"msg": "serverf.lab.example.com"
}
网络信息过滤器
ipaddr 过滤器可用于处理和验证网络相关的事实：
- 检查IP地址的语法
- 转换VLSN子网掩码为CIDR子网
- 执行子网数学运算
- 在网络范围内找到下一个可用地址
使用要求：RHEL8系统使用ipaddr过滤器需要安装 python3-netaddr 软件包，该包提供Python模块netaddr。
[student@workstation laomalS sudo yum install -y python3-netaddr
ipaddr 过滤器提供了操作和验证与网络相关的事实功能。
可以用于检查 IP 地址的语法，从 VLSN 子网掩码转换为 CIDR 子网前缀表示法，执行子网计算，查找网络范围内的下一个可用地址等。
在最简单的形式中，不带参数的 ipaddr 过滤器接受单个值。如果值是 IP 地址，则过滤器返回 IP 地址，如果不是IP 地址，则过滤器将返回 False。
- 如果该值为有效的P地址，则过滤器将返回地址。
- 如果该值不是有效的IP地址，则过滤器返回False。
$ ansible servera -m debug -a 'msg={
{ "175.25.250.50" | ipaddr}}'
servera | SUCCESS => {
"msg": "175.25.250.50"
}
$ ansible servera -m debug -a 'msg={
{ "175.25.250.50/24" | ipaddr}}'
servera | SUCCESS => {
"msg": "175.25.250.50/24"
}
$ ansible servera -m debug -a 'msg={
{ "175.25.250.500/24" | ipaddr}}'
servera | SUCCESS => {
"msg": false
}
ipaddr过滤器接受参数值：
- 如果该值包涵有效的IP地址，则返回有效的IP地址。
- 如果所有项目均无效，则返回一个空列表。
$ ansible servera -m debug -a 'msg={
{ "175.25.250.50/24" | ipaddr("netmask")}}'
servera | SUCCESS => {
"msg": "255.255.255.0"
}
$
- ipaddr 过滤器接受以下选项：
- address：验证输入值是否为有效的 IP 地址，如果输入中包含网络前缀，其会被剥离。
- net：验证输入值是否为网络范围，并以 CIDR 格式返回。
- host：确保 IP 地址符合等效的 CIDR 前缀格式。
- prefix：验证输入主机是否满足主机/前缀或 CIDR 格式，并返回前缀。
- host/prefix：验证输入是否为网络/前缀格式。
- public 或 private：验证输入 IP 地址或网络范围是否由 IANA 分别预留为公共或私有的范围内。
- size：将输入网络范围转换为该范围内的 IP 地址数。
- n：任何整数。将网络范围转换为该范围内的第 N 个元素。负数返回从最后一个数的第 n 个元素。
- network、netmask、broadcast：验证输入主机是否满足主机/前缀或CIDR格式，并将其分别转换为网络地址、子网掩码或广播地址。
- subnet：验证输入主机是否满足主机/前缀或 CIDR 格式，并返回包含该主机的子网。
- ipv4 ipv6：验证输入是否有效的网络范围，并将它们分别转换为 ipv4 和 ipv6 格式。
$ ansible servera -m debug -a 'msg={
{ "175.25.250.50/24" | ipaddr("ipv6")}}'
servera | SUCCESS => {
"msg": "::ffff:175.25.250.50/120"
}
$ ansible servera -m debug -a 'msg={
{ "175.25.250.50/24" | ipaddr("subnet")}}'
servera | SUCCESS => {
"msg": "175.25.250.0/24"
}
$ ansible servera -m debug -a 'msg={
{ "175.25.250.50/24" | ipaddr("size")}}'
servera | SUCCESS => {
"msg": "256"
}
使用插件收集网络信息
查找 DNS 信息
dig 命令针对 DNS 服务进行查询，并返回生成的记录。dig 需要在控制节点上安装 python3-dns 软件包。
$ ansible servera -m debug -a 'msg={
{ lookup("dig","servera.lab.example.com")}}'
servera | SUCCESS => {
"msg": "172.25.250.10"
}
$ ansible servera -m debug -a 'msg={
{ lookup("dig","example.com")}}'
servera | SUCCESS => {
"msg": "172.25.254.254"
}
$ ansible servera -m debug -a 'msg={
{ lookup("dig","com")}}'
servera | SUCCESS => {
"msg": "NXDOMAIN"
}
dig 查找 DNS 服务器中是否存在提供 FQDN 的 A 记录：
$ ansible servera -m debug -a 'msg={
{ lookup("dig","example.com", "qtype=A")}}'
servera | SUCCESS => {
"msg": "10 classroom.example.com."
}
$ ansible servera -m debug -a 'msg={
{ lookup("dig","example.com", "@")}}'
servera | SUCCESS => {
"msg": "172.25.254.254"
}
一个 Demo
[student@workstation netfilters]$ cat ./tasks/main.yml
# Complete each task by setting the fact as the expected value.
# Replace ellipsis by the appropriate filter usage.
# All task but the last one should be using the 'ipaddr' filter.
# Use the lookup filter with the `dig` command for the last task
# Tasks make use of th gathered fact 'default_ipv4', and its keys 'address', 'network' and 'netmask'
- name: Task 1- Verify the 'ansible_default_ipv4.addresss' provided address is correctly formatted.
set_fact:
server_address: "{
{ ansible_facts.default_ipv4.address | ipaddr }}"
- name: Task 2- Check 'server_address' value
assert:
that: "server_address == ansible_facts.default_ipv4.address"
fail_msg: "'server_address' must be {
{ ansible_facts.default_ipv4.address }}, but is {
{ server_address }}"
- name: Task 3- Obtain the DNS name associated to the server IP address (reverse DNS)
set_fact:
address_dns: "{
{ server_address | ipaddr('revdns') }}"
- name: Task 4- Check 'address_dns' value
assert:
that: "address_dns == '10.250.25.172.in-addr.arpa.'"
fail_msg: "'address_dns' must be '10.250.25.172.in-addr.arpa.', but is {
{ address_dns }}"
- name: Task 5- Obtain server's network/netmask
set_fact:
net_mask: "{
{ ansible_facts.default_ipv4.network }}/{
{ ansible_facts.default_ipv4.netmask }}"
- name: Task 6- Check 'net_mask' value
assert:
that: "net_mask == '172.25.250.0/255.255.255.0'"
fail_msg: "'net_mask' must be '172.25.250.0/255.255.255.0', but is {
{ net_mask }}"
- name: Task 7- Transform the network/netmask to the CIDR format
set_fact:
cidr: "{
{ net_mask | ipaddr('net') }}"
- name: Task 8- Check 'cidr' value
assert:
that: "cidr == '172.25.250.0/24'"
fail_msg: "'cidr' must be '172.25.250.0/24', but is {
{ cidr }}"
- name: Task 9- Verify the server address actualy belong to the network/mask
set_fact:
address_in_range: "{
{ server_address | ipaddr(net_mask) }}"
- name: Task 10- Check 'address_in_range' value
assert:
that: "address_in_range == server_address"
fail_msg: "'address_in_range' must be {
{ server_address }}, but is {
{ address_in_range }}"
- name: Task 11- Obtain the broadcast address associated to the CIDR
set_fact:
broadcast: "{
{ cidr | ipaddr('broadcast') }}"
- name: Task 12- Check 'broadcast' value
assert:
that: "broadcast == '172.25.250.255'"
fail_msg: "'broadcast' must be '172.25.250.255', but is {
{ broadcast }}"
- name: Task 13- DIG for the MX record of the domain 'example.com'
set_fact:
dig_record: "{
{ lookup( 'dig', 'example.com.', 'qtype=MX') }}"
- name: Task 14- Check 'dig_record' value
assert:
that: "dig_record == '10 classroom.example.com.'"
fail_msg: "'dig_record' must be '10 classroom.example.com.', but is '{
{ dig_record }}'"
[student@workstation data-netfilters]$ ansible-playbook site.yml
PLAY [Tasks for netfilter guided exercise] *****************************************************************************
TASK [Gathering Facts] *************************************************************************************************
ok: [servera.lab.example.com]
TASK [netfilters : Task 1- Verify the 'ansible_default_ipv4.addresss' provided address is correctly formatted.] ********
ok: [servera.lab.example.com]
TASK [netfilters : Task 2- Check 'server_address' value] ***************************************************************
ok: [servera.lab.example.com] => {
"changed": false,
"msg": "All assertions passed"
}
TASK [netfilters : Task 3- Obtain the DNS name associated to the server IP address (reverse DNS)] **********************
ok: [servera.lab.example.com]
TASK [netfilters : Task 4- Check 'address_dns' value] ******************************************************************
ok: [servera.lab.example.com] => {
"changed": false,
"msg": "All assertions passed"
}
TASK [netfilters : Task 5- Obtain server's network/netmask] ************************************************************
ok: [servera.lab.example.com]
TASK [netfilters : Task 6- Check 'net_mask' value] *********************************************************************
ok: [servera.lab.example.com] => {
"changed": false,
"msg": "All assertions passed"
}
TASK [netfilters : Task 7- Transform the network/netmask to the CIDR format] *******************************************
ok: [servera.lab.example.com]
TASK [netfilters : Task 8- Check 'cidr' value] *************************************************************************
ok: [servera.lab.example.com] => {
"changed": false,
"msg": "All assertions passed"
}
TASK [netfilters : Task 9- Verify the server address actualy belong to the network/mask] *******************************
ok: [servera.lab.example.com]
TASK [netfilters : Task 10- Check 'address_in_range' value] ************************************************************
ok: [servera.lab.example.com] => {
"changed": false,
"msg": "All assertions passed"
}
TASK [netfilters : Task 11- Obtain the broadcast address associated to the CIDR] ***************************************
ok: [servera.lab.example.com]
TASK [netfilters : Task 12- Check 'broadcast' value] *******************************************************************
ok: [servera.lab.example.com] => {
"changed": false,
"msg": "All assertions passed"
}
TASK [netfilters : Task 13- DIG for the MX record of the domain 'example.com'] *****************************************
ok: [servera.lab.example.com]
TASK [netfilters : Task 14- Check 'dig_record' value] ******************************************************************
ok: [servera.lab.example.com] => {
"changed": false,
"msg": "All assertions passed"
}
PLAY RECAP *************************************************************************************************************
servera.lab.example.com : ok=15 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
[student@workstation data-netfilters]$ cat site.yml
- name: Tasks for netfilter guided exercise
hosts: servera.lab.example.com
roles:
- role: netfilters
[student@workstation data-netfilters]$
博文参考
《DO447》