Palo Alto Networks, maker of hardware firewalls that offer controls over applications, has announced plans to file for an initial public offering (IPO) to raise up to $175 million in stock. According to a Wall Street Journal report, the Santa Clara, Calif.-based company, founded in 2005, reported a $12.5 million loss for the fiscal year ending July 31, but its revenue doubled to nearly $120 million. Founded by Nir Zuk, the vendor dealt with some internal turmoil in December 2010 when CEO Lane Bess suddenly resigned amid disagreements with the board of directors over future direction. He was replaced by former VeriSign CEO Mark McLaughlin. Imperva was the most recent security firm to go public.