https://github.com/hdfgroup/dynamic-dns
A dynamic DNS server for mapping files to DNS entries
https://github.com/hdfgroup/dynamic-dns
Last synced: 12 months ago
JSON representation
A dynamic DNS server for mapping files to DNS entries
- Host: GitHub
- URL: https://github.com/hdfgroup/dynamic-dns
- Owner: HDFGroup
- License: other
- Created: 2016-01-11T04:29:12.000Z (over 10 years ago)
- Default Branch: master
- Last Pushed: 2016-07-12T04:37:44.000Z (almost 10 years ago)
- Last Synced: 2025-02-12T18:32:14.052Z (over 1 year ago)
- Language: Python
- Size: 8.79 KB
- Stars: 4
- Watchers: 5
- Forks: 0
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: COPYING
Awesome Lists containing this project
README
********************
Dynamic DNS
********************
A simple dynamic DNS server server that returns the host IP address for any sub-domain.
This DNS server can optionally be used with the HDF Server (see https://github.com/HDFGroup/h5serv)
if you would like to display data from h5serv using a web browser without needing to specify a "host"
query parameter.
Background
-----------
The HDF5 REST api exposes each HDF5 file as a domain object. E.g.
If the file "hdf_data.h5" is in the data directory, and the 'domain' config in server.py
is set to "mydata.myorg.org", the file is mapped to the domain path:
*hdf_data.mydata.myorg.org*.
When the HDF REST Service is accessed programmatically, the http request can be sent
to the endpoint where h5serv is running and dynamic_dns.py is not needed. In this case it is
important that the request host header provide the domain path above.
Example:
.. code-block:: http
GET / HTTP/1.1
Host: hdf_data.myserv.myorg.org
The service will look at the Host header line to determine which HDF5 file the ``GET /``
request refers to and return the appropriate response.
However, if you type `http://hdf_data.mydata.myorg.org` in your favorite web browser you
will most likely get a DNS lookup failure. These is because the DNS server your browser
is talking to doesn't know how to resolve the domain name: `hdf_data.mydata.myorg.org`.
You can verify this by running: `nslookup hdf_data.mydata.myorg.org`, you should see a response:
`** server can't find hdf_data.mydata.myorg.org`.
You can imagine getting around this by configuring special DNS lookup rules for each
HDF5 file managed by h5serv, but this would require a config update every time a new
file was created (say by a ``PUT /`` request).
The DNS server in this repository, dynamic_dns.py, avoids this issue by simply
responding to any DNS request with the configured base domain name to the IP address of h5serv.
Any request that doesn't map to the base domain name will be forwarded to a regular DNS
server.
So a request to resolve `hdf_data.myserv.myorg.org` would return the IP address of h5serv,
while a request to resolve `www.google.com` would be forwarded to a standard DNS server.
Running dynamic_dns
-------------------
Before starting the dynamic_dns server, update the local_ip, and default_dns config values
in config.py to what makes sense for your network. Using the above example, domain would
be myserv.myorg.org and local_ip can be left as just 127.0.0.1 if we are running h5serv and
dynamic_dns on the same host.
Next, start the dynamic_dns server: `sudo python dynamic_dns.py`
*Note:* You will need to run as root since dynamic_dns using port 53 (the standard DNS port).
Now when you run: `nslookup hdf_data.mydata.myorg.org 127.0.0.1`, you should see a response:
`Non-authoritative answer:`
`Name: hdf_data.mydata.myorg.org`
`Address: 127.0.0.1`
dynamic_dns has resolved the domain name hdf_data.mydata.myorg.org to the local ip address.
If at this point you modify your machine's dns configuration to use the IP address where
dynamic_dns.py is running, you'll be able to use: hdf_data.mydata.myorg.org/ as a browser
url and see the JSON response.
Integrating with you organization's network
-------------------------------------------
If you would like *any* computer to recognize the domain name of hdf_data.myserv.myorg.org
you will need to have your system admin update your organization's master DNS server to
configure "myserv" as a zone of "myorg". In our example, this would have the effect
of any sub-domain of "myserv.myorg" managed by its own DNS server. In our case, the DNS
server will be dynamic_dns.py. Details of how zone's are setup will vary based on
what DNS server software your network is running. Your sysadmin should be able to help.
An Example
----------
As an example of how this would work we can look at the h5serv instance setup by The HDF
Group. Entering http://tall.data.hdfgroup.org:7253/ in your browser will return the JSON
domain response for tall.h5.
If we trace the chain of events in displaying this page it
would be something like this (the actual IP address may be different than what you see here):
1. User enters `http://tall.data.hdfgroup.org:7253` in the browser
2. The browser sends the domain "tall.data.hdfgroup.org" to its normal DNS server
3. If the DNS server is not familiar with "hdfgroup.org" it forwards the request to the root domain server
4. The root domain server resolves "hdfgroup.org" the IP address 50.28.50.143
5. The HDFGroup DNS server at 50.28.50.143 gets the request to resolve "data.hdfgroup.org"
6. The HDF Group DNS server sees that "data" maps to a zone managed by the DNS server (dynamic_dns) at IP address 54.174.38.12
7. Finally, the dynamic_dns.py service gets the DNS request and resolves the name "tall.data.hdfgroup.org" and returns the IP address 54.174.38.12 and returns the requested IP to the browser
8. With the dns name resolved, the browser sends the original http request to port 7253 on the machine with IP address 54.174.38.12.
9. This request is processed by h5serv which returns a http status of 200 followed by the response body
10. The browser renders the response:
```
{
root: "345239f2-963f-11e4-b8cf-06fc179afd5e",
created: "2015-01-07T07:31:33.294348Z",
lastModified: "2015-01-07T07:31:33.294348Z",
hrefs: [
{href: "http://tall.data.hdfgroup.org:7253/", rel: "self"},
{href: "http://tall.data.hdfgroup.org:7253/datasets", rel: "database"},
{href: "http://tall.data.hdfgroup.org:7253/groups", rel: "groupbase"},
{href: "http://tall.data.hdfgroup.org:7253/datatypes",rel: "typebase"},
{href: "http://tall.data.hdfgroup.org:7253/groups/345239f2-963f-11e4-b8cf-06fc179afd5e",rel: "root"}
]
}
```