When connecting to the New York City Subway's new Transit Wireless service, my iPhone raised these warnings:

Security Recommendation Unsecured Network

Is it dangerous to use this service? Is it really just a normal unsecured wireless network, or is there some security here that iOS is just unaware of?


When you connect to an open public wifi network without any security settings such as your local Starbucks, everything transferred over that network is sent in plaintext. Anyone sniffing the network could intercept the traffic, and potentially modify it. If you're connecting to one of these networks, it's best that you then connect to a VPN to encrypt your traffic so that it can't be captured or modified.

  • And there is no way to secure an open network whatsoever, that could have been implemented in this case (e.g. key exchange like SSL)?
    – JHZ
    Oct 17 '16 at 15:14
  • You are connecting to a public network, so there is no expectation of security/privacy as a general rule. If you are connecting to a specific website using HTTPS, then communications with that particular site will be encrypted. This is a good first step to staying secure on an open network, however any connections to sites that are not using SSL will still be in the clear, and any other non-web related traffic (applications accessing the Internet that are not the web browser) will still be sending data unencrypted, which is why it is best to use a VPN.
    – John
    Oct 17 '16 at 15:26
  • Sorry, what I mean is securing the password-less network entirely (not just HTTPS traffic) by using SSL-like encryption between the router and devices. I can ask that separately, though.
    – JHZ
    Oct 17 '16 at 18:41
  • Seeing as you don't have control over the public network, you will need to find a way to encrypt your traffic before sending it from your device. Without going into the technical details, a virtual private network (VPN) is essentially an encrypted tunnel through which you can pass your data while you're connected to the wifi. Your VPN client encrypts the data before it's sent over the public wifi, and it sends it along to another server, which decrypts it and forwards it to the destination. Some home routers allow you to create a VPN, or you can find a paid service.
    – John
    Oct 19 '16 at 0:03

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