How can I see if there's an available and active network connection in Python?

Question

I want to see if I can access an online API, but for that, I need to have Internet access. How can I see if there's a connection available and active using Python?

Accepted Answer

Perhaps you could use something like this:

```
from urllib import request

def internet_on():
    try:
        request.urlopen('http://216.58.192.142', timeout=1)
        return True
    except request.URLError as err: 
        return False
```

For Python 2.x replace the import statement by `import urllib2 as request`:

Currently, 8.8.8.8 is one of the IP addresses from Google. Change `http://8.8.8.8` to whatever site can be expected to respond quickly.

This fixed IP will not map to google.com forever. So this code is not robust -- it will need constant maintenance to keep it working.

The reason why the code above uses a fixed IP address instead of fully qualified domain name (FQDN) is because a FQDN would require a DNS lookup. When the machine does not have a working internet connection, the DNS lookup itself may block the call to `urllib_request.urlopen` for more than a second. Thanks to @rzetterberg for pointing this out.

If the fixed IP address above is not working, you can find a current IP address for google.com (on unix) by running

```
% dig google.com  +trace 
...
google.com.     300 IN  A   216.58.192.142
```

How can I see if there's an available and active network connection in Python?

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