During the first half-hour after the Hanukah candles are lit, they may not be used for other purposes than publicizing the Hanukah miracle. Clearly, then, one may not light a cigarette, for example, from the Hanukah candles. Strictly speaking, it is permissible to make personal use of the candles after they have burned for a half-hour. Preferably, however, one should avoid making personal use of the candles at any point, out of respect for the Misva.
The Shulhan Aruch (Orah Haim 672) rules that one may light one of the Hanukah candles directly from another Hanukah candle. This means that after one lit the first candle, for example, he may extend the wick of that candle to the adjacent candle to light it. Although it is forbidden to use the Hanukah candles, as they are designated exclusively for the Misva, one may use a candle to light another candle, since this is for the purpose of the Misva. And although only the first candle is needed to fulfill the strict obligation, and the others are lit only for the sake of "Hiddur" (glorifying the Misva), nevertheless, all the candles relate to the Misva, and thus lighting any of the candles is considered a Misva. It is therefore permissible to light any of the Hanukah candles from any of the other Hanukah candles.
However, this applies only to the candles lit for the Misva. If the Shamosh is extinguished, one may not relight it from one of the Hanukah candles, as he would then be using a candle of Misva for a non-Misva purpose, since the Shamosh is not part of the Misva.
Furthermore, this Halacha applies only to lighting a candle for the first time. If, however, a Hanukah candle was lit and subsequently extinguished, one may not relight it from one of the other Hanukah candles. This is the ruling of the Magen Abraham (Rabbi Abraham Gombiner, Poland, 1637-1683), who explains that Halacha follows the view of "Kabeta En Zakuk Lah" meaning, if a Hanukah candle is extinguished, then one does not have to rekindle it. As long as the candle was lit with enough oil and under conditions that ordinarily allow it to burn for at least a half-hour, one does not have to rekindle it if it happens to be extinguished. Accordingly, the Magen Abraham notes, if a candle is extinguished, relighting it does not fulfill a Misva, and therefore another Hanukah candle may not be used for this purpose. One would have to use the Shamosh to relight the candle, or strike a match to make a new flame with which to rekindle the extinguished flame.
Summary: It is forbidden to use the Hanukah candles for any purpose during the first half-hour after they are lit, and, preferably, even after the first half-hour. One may, however, use a Hanukah candle to light one of the other Hanukah candles (but not the Shamosh). If a Hanukah candle was already lit and subsequently extinguished, one may not relight it from another Hanukah candle.
