Hereford needed some solid defensive work by Trent McClenahan and John McCombe to survive Posh's opening burst and Wayne Brown saved well, dropping on a snap-shot from George Boyd when a stylish four-man move did manage to find a way through.
Although Posh keeper Mark Tyler sometimes looked uncertain dealing with crosses, the greatest first-half threat to the home goal came when defender Chris Westwood sliced a clearance that flashed inches wide of a post.
Darren Ferguson's Posh grabbed the advantage a couple of minutes before the break with Hereford down to ten men while McClenahan received attention to a head injury.
Adam Newton cut in from the right and side-stepped Kris Taylor's lunging challenge before hitting a low cross that Craig Mackail-Smith tapped home from close range.
Charlie Lee and Mackail-Smith were close to adding to the home advantage before Posh tended to sit back and allow Hereford to move forward.
Ben Smith saw a glancing header flash just wide after he connected with a Taylor cross before former Wycombe man Easton brought scores level.
The youngster beat Newton in a tussle for a loose ball and then whacked a low 20-yard drive out of Tyler's reach and into the far corner of the net.
There were late chances at either end with ex-Posh man Trevor Benjamin climbing to head wide following a corner before Boyd lifted a last-minute chance over the Hereford bar.