Sefer Ha’mitzvos Ha’Katzar (The concise book of mitzvos)
By the Chofetz Chaim
This book lists the Torah mitzvos that can be observed today
First Section – the Positive Commandments
35. It is a positive commandment to dwell in a Sukkah (booth) for the seven days of Succos
As it says in Vayikra (Leviticus) 23:42, "You shall live in Succos (booths) for seven days." For all seven days of Succos a person should eat, drink, and live in the Succah, day and night. All seven days he should make his home a temporary dwelling and his Succah a permanent dwelling. It is forbidden to eat a meal outside of the Succah. On the first night of Succos, a person is obligated to eat at least a kazi'as (olive size) of bread. After that time, if a person wants to eat bread, he must eat it in the Succah, but if all he wants to eat is fruit, he is allowed to eat it outside of the Succah [but of course, he is certainly allowed to eat it in the Succah if he wants to, and is praiseworthy if he does]. A child who has reached the age of training is obligated in the commandment of Succah according to the Sages.
This is obligated in all places and at all times, for men but not for women.