The only way to keep communication truly secure is to use end-to-end encryption. For example, when accessing an internet bank, one would almost always use strong encryption from the web browser and all the way to the bank – thus it shouldn't be risky to do banking over an unencrypted wireless network. The argument is that anyone can sniff the traffic applies to wired networks too, where system administrators and possible hackers have access to the links and can read the traffic. Also, anyone knowing the keys for an encrypted wireless network can gain access to the data being transferred over the network. If services like file shares, access to printers etc. are available on the local net, it is advisable to have authentication (i.e. by password) for accessing it (one should never assume that the private network is not accessible from the outside). Correctly set up, it should be safe to allow access to the local network to outsiders. With the most popular encryption algorithms today, a sniffer will usually be able to compute the network key in a few minutes. It is very common to pay a fixed monthly fee for the Internet connection, and not for the traffic – thus extra traffic will not be detrimental. Where Internet connections are plentiful and cheap, freeloaders will seldom be a prominent nuisance. On the other hand, in some countries including Germany, persons providing an open access point may be made (partially) liable for any illegal activity conducted via this access point. Also, many contracts with ISPs specify that the connection may not be shared with other persons. See also Aircrack-ng Electromagnetic shielding Kismet KRACK List of router firmware projects Mobile security Payment Card Industry Data Security Standard Stealth wallpaper Tempest (codename) Wireless intrusion prevention system Wireless Public Key Infrastructure (WPKI) References Wi-Foo: The Secrets of Wireless Hacking (2004) – Real 802.11 Security: Wi-Fi Protected Access and 802.11i (2003) – Design and Implementation of WLAN Authentication and Security(2010) – Boyle, Randall, Panko, Raymond. Corporate Computer Security. Upper Saddle River, New Jersey. 2015 External links How to Secure Your Wireless Home Network at wikiHow Computer network security Security