Is it permitted (while traveling, or anytime really) when using the internet in a public place to use someone elses internet connection? Idont know them or where it comes from and it just shows up on my computer a s a possible connection; can I assume (as it probably doesn’t) affect them and therefore is permissible?
It is permitted to an unprotected wireless connection in a public place. Anybody who has an unsecured wireless connection knows that neighbors or passers-by will be able to utilize it, and their leaving the connection unsecured implies a tacit granting of permission for doing so.
Please see https://dinonline.org/2010/11/11/using-neighbors-wireless-connection/ for a deeper analysis of a slighly more involved question.