Combat Awareness (D20 Modern Feat)
From D&D Wiki
Your battle sense helps minimize the threat of flanking attacks.
Prerequisite: Wis 13+, BAB +1 or higher.
Benefit: Attackers do not gain the usual +2 bonus on their attack rolls when flanking you. This feat grants no effect when you are denied your Dexterity modifier to Defense, such as when you are flat-footed. You may still be sneak attacked when flanked.