Blue Coat Systems Inc posted quarterly results that whizzed past Wall Street estimates and forecast a strong third quarter, sending the Internet-monitoring gear maker's shares up 17 percent in extended trade.

The company, which has been struggling to grow revenue and facing increasing competition from a number of more nimble rivals, projected third-quarter revenue of $113-$120 million, compared with analysts' expectations of $108.2 million, according to Thomson Reuters I/B/E/S.

For the August-September quarter, Blue Coat earned $4.6 million, or 10 cents a share, compared with $12 million, or 25 cents a share, a year ago.

Excluding special items, earnings came in at 20 cents a share. Analysts were looking for earnings of 13 cents a share.

Blue Coat, which counts Websense Inc among its rivals, posted sales of $114.1 million, beating sales estimates of $105.5 million. Service revenue rose 8 percent to $51.8 million in the quarter.

Shares of the Sunnyvale, California-based company were up 17 percent to $19.77 in extended trading. They closed at $16.91 on Thursday on Nasdaq.

(Reporting by Siddharth Cavale in Bangalore; Editing by Viraj Nair)