OpenDNS, a provider of internet security, has closed a $4.5 million round of funding, according to a filing with the SEC. Sequoia Capital and Greylock Partners participated in the round.

Based in San Francisco, the free Domain Name System (DNS) service provides individuals, schools and businesses with phishing protection, parental controls and typo corrections for misspelled URLs. OpenDNS also operates a web site called the Phish Tank that allows users to submit suspected phishing sites. Earlier this month, the firm announced that it has identified more than 1 million phishing links.

Founded in 2005, OpenDNS generates revenue from ads and first raised $2.5 million from CNET founder Halsey Minor in 2005.