I have signed up with
https://www.opendns.com (free) and have setup DNS restrictions for inappropriate content.
So even if they navigate to the wrong site (for whatever reason) it just shows that you're not allowed..
"This site is blocked due to content filtering."
Very simple and pretty safe, also safe for your day to day to protect you from DNS phishing..
Good luck!
Here are the filtering levels so you get the idea:
High
Protects against all adult-related sites, illegal activity, social networking sites, video sharing sites, and general time-wasters.
Moderate
Protects against all adult-related sites and illegal activity.
Low
Protects against pornography.
None
Nothing blocked.
Custom
Choose the categories you want to block.
In the
moderate level (as an example here are the categories:
Adware
Sites that distribute applications which display advertisements without user's knowledge or choice. Does NOT include sites which serve advertising.
Alcohol
Sites about alcohol use, commercial and otherwise.
Dating
Sites for meeting other people.
Drugs
Sites about illegal or recreational drug use.
Gambling
Sites that offer gambling or information about gambling.
Hate/Discrimination
Sites that promote intolerance based on gender, age, race, nationality, religion, sexual orientation or other group identities.
Weapons
Sites about weapons, commercial and otherwise.
Tasteless
Sites that contain information on such subjects as mutilation, torture, horror, or the grotesque. Includes Pro-Anorexia and Pro-Suicide related sites.
Lingerie/Bikini
Sites displaying or dedicated to lingerie/bikini that could be considered adult-only.
Proxy/Anonymizer
Sites providing proxy bypass information or services. Also, sites that allow the user to surf the net anonymously, including sites that allow the user to send anonymous emails.
Sexuality
Sites that provide information, images or implications of bondage, sadism, masochism, fetish, beating, body piercing or self-mutilation. This category is not intended for LGBT related sites that do not fall under the aforementioned criteria.
Nudity
Sites that provide images or representations of nudity.
Pornography
Anything relating to pornography, including mild depiction, soft pornography or hard-core pornography.