1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
|
+++
date = 2022-02-10
title = "Dynamic DNS with Njalla API"
description = "Learn how to dynamically update DNS records for changing IPs with Njalla."
+++
## Njalla's API
As noted in my recent post about [switching to Njalla from
Cloudflare](/blog/ditching-cloudflare/), I was searching for a
way to replace my very easy-to-use bash script to [update Cloudflare's
DNS via their API](/blog/cloudflare-dns-api/).
To reiterate what I said in those posts, this is a common necessity for
those of us who have non-static IP addresses that can change at any
moment due to ISP policy.
In order to keep a home server running smoothly, the server admin needs
to have a process to constantly monitor their public IP address and
update their domain's DNS records if it changes.
This post explains how to use Python to update Njalla's DNS records
whenever a machine's public IP address changes.
### Creating a Token
To use Njalla's API, you will first need to create a token that will be
used to authenticate you every time you call the API. Luckily, this is
very easy to do if you have an account with Njalla.
Simply go the [API Settings](https://njal.la/settings/api/) page and
click the `Add Token` button. Next, enter a name for the
token and click `Add`.
Finally, click the `Manage` button next to your newly created
token and copy the `API Token` field.
### Finding the Correct API Request
Once you have a token, you're ready to call the Njalla API for any
number of requests. For a full listing of available requests, see the
[Njalla API Documentation](https://njal.la/api/).
For this demo, we are using the `list-records` and
`edit-record` requests.
The `list-records` request requires the following payload to
be sent when calling the API:
```txt
params: {
domain: string
}
```
The `edit-record` request requires the following payload to
be sent when calling the API:
```txt
params: {
domain: string
id: int
content: string
}
```
## Server Set-Up
To create this script, we will be using Python. By default, I use Python
3 on my servers, so please note that I did not test this in Python 2,
and I do not know if Python 2 will work for this.
### Creating the Script
First, find a suitable place to create your script. Personally, I just
create a directory called `ddns` in my home directory:
```sh
mkdir ~/ddns
```
Next, create a Python script file:
```sh
nano ~/ddns/ddns.py
```
The following code snippet is quite long, so I won't go into depth on
each part. However, I suggest you read through the entire script before
running it; it is quite simple and contains comments to help explain
each code block.
:warning: **Note**: You will need to update the following variables for
this to work:
- `token`: This is the Njalla API token you created
earlier.
- `user_domain`: This is the top-level domain you want to
modify.
- `include_subdomains`: Set this to `True` if
you also want to modify subdomains found under the TLD.
- `subdomains`: If `include_subdomains` =
`True`, you can include your list of subdomains to be
modified here.
```python
#!/usr/bin/python
# -*- coding: utf-8 -*-
# Import Python modules
from requests import get
import requests
import json
# Set global variables
url = 'https://njal.la/api/1/'
token = '<your-api-token>'
user_domain = 'example.com'
include_subdomains = True
subdomains = ['one', 'two']
# Main API call function
def njalla(method, **params):
headers = {'Authorization': 'Njalla ' + token}
response = requests.post(url, json={'method': method,
'params': params}, headers=headers).json()
if 'result' not in response:
raise Exception('API Error', response)
return response['result']
# Gather all DNS records for a domain
def get_records(domain):
return njalla('list-records', domain=user_domain)
# Update a DNS record for a domain
def update_record(domain, record_id, record_content):
return njalla('edit-record', domain=domain, id=record_id,
content=record_content)
# Get public IP addresses
ipv4 = get('https://api.ipify.org').text
print('IPv4: {}'.format(ipv4))
ipv6 = get('https://api64.ipify.org').text
print('IPv6: {}'.format(ipv6))
# Call API to get all DNS records
data = get_records(user_domain)
# Loop through records and check if each one is IPv4 (A) or IPv6 (AAAA)
# Update only if DNS is different from server IP
for record in data['records']:
if record['name'] == '@' or (include_subdomains and record['name'] \
in subdomains):
if record['type'] == 'A':
if record['content'] == ipv4:
print(record['type'], 'record for', record['name'],
'already matches public IPv4 address. Skipping...'
)
else:
print('IPv4 of', ipv4,
'does not match Njalla's value of',
record['content'], '. Updating...')
update_record(user_domain, record['id'], ipv4)
elif record['type'] == 'AAAA':
if record['content'] == ipv6:
print(record['type'], 'record for', record['name'],
'already matches public IPv6 address. Skipping...'
)
else:
print('IPv6 of', ipv6,
'does not match Njalla's value of',
record['content'], '. Updating...')
update_record(user_domain, record['id'], ipv6)
```
### Running the Script
Once you've created the script and are ready to test it, run the
following command:
```sh
python3 ~/ddns/ddns.py
```
### Setting the Script to Run Automatically
To make sure the scripts run automatically, add it to the
`cron` file so that it will run on a schedule. To do this,
open the `cron` file:
```sh
crontab -e
```
In the cron file, paste the following at the bottom of the editor in
order to check the IP every five minutes:
```sh
*/5 * * * * python3 /home/<your_username>/ddns/ddns.py
```
|
