The gemara says that ideally one should light his chanuka candles OUTSIDE his front door [or courtyard] in the רשות הרבים [public domain]. Only during a time of religious oppression is it permitted to light inside. The question then presents itself - Why are do many people still have the custom to light inside. There is [thank G-d!!] no longer any fear of repercussions from the Gentiles [except maybe in Iran]?
The Rebbe Shlita says a mind-blowing idea. In the olden days the public domain was public and the private domain was private. When you went home you were freed from any association with the outside world. Today things are different. The רשות הרבים has penetrated our inner sanctum. So when we light inside it is just as if we have lit in the רשות הרבים.
פלאי פלאות.
I would like to add that there is a famous-famous [after all of my readers read this post it will be that much more famous] teshuva of the Dvar Yehoshua [סימן מ of Rav Yehoshua Ehrenberg ztz"l who was a Rov in Europe, survived the holocaust and came to Tel Aviv Hakodesh] where he says a huge chiddush. Not only does he justify the custom to light inside, but he goes further. He says that in our day and age one MUST light inside, otherwise he has not properly fulfilled his obligation. I am not going to tell you his rationale because it is my fervent wish that after getting a daily dose of Mevakesh, people open up tshuvos sefarim and "kinock in lernen" [after the daf yomi, halacha yomis, tehillim yomi, nach yomi, tanya yomi and a regular iyun seder:-)]. With the insight of Mori V'Rabi Shlita maybe we have another reason. People must be reminded today more than ever about the dangers of the רשות הרבים which permeates our homes.
OF COURSE, הלכה למעשה one follows his or her Rov....