wget https://raw.githubusercontent.com/Jesssullivan/misc/master/sel/portal.py

Some distros (Ubuntu and its derivatives on my Macbook for instance) struggle to find a route to the captive portal on public networks (read: Starbucks). Assuming you want to connect the way they intend (via the gateway through the captive portal) because you are a rule abiding patron, all you need to do is visit the address of the gateway. There is no need to fiddle with your network drivers, disable SSL stuff or engage in plebian network tomfoolery.

"""
find and open wifi captive portal (such as Starbucks)
written by Jess Sullivan
"""
from netifaces import gateways
from sys import argv
from time import sleep
import subprocess

help_str = str("\n " +
               'usage: \n ' +
               ' -h : print this message again \n' +
               ' -i : `pip3 install netifaces`  \n' +
               'You may specify a browser argument to complete the portal, such as \n' +
               'google-chrome')

def argtype():
    try:
        if len(argv) > 1:
            use = True
        elif len(argv) == 1:
            use = False
            print(help_str)
        else:
            print('command takes 0 or 1 args, use -h for help')
            raise SystemExit
    except:
        print('arg error... \n command takes 0 or 1 args, use -h for help')
        raise SystemExit
    return use

def main():

    all_gates = gateways()
    target = all_gates['default'][2][0]

    if argtype():

        if argv[1] == '-h':
            print(help_str)
            quit()

        if argv[1] == '-i':
            try:
                subprocess.Popen('pip3 install netifaces',
                                 shell=True,
                                 executable='/bin/bash')
                sleep(1)
                quit()
            except:
                print('err running pip3 install netifaces')
                quit()

        else:

            print(str('opening portal in ' + argv[1]))
            subprocess.Popen(str(argv[1] + ' ' + str(target)),
                             shell=True,
                             executable='/bin/bash')
            sleep(1)
            quit()

    else:

        print(str('\n please visit address ' + target +
                  ' in a browser to complete portal setup \n'))
        quit()

main()