Last time around the Spitfires were one of the most open teams in the National League.
They let in 72 goals - more than any side who finished outside the division’s bottom four.
Hessenthaler has been in charge of Dover Athletic, Leyton Orient and Gillingham and made it his summer question to improve his backline this summer.
Maidstone defender Alex Wynter joins and with Woking’s Joey Jones, the holding central midfielder, on board they should be harder to beat.
But they need injury luck too with centre-backs Ryan Cresswell and Reda Johnson missing large chunks of last season.
The manager said: “It’s not a big secret that defensively we weren’t good enough last season.
“The aim this summer was about putting that right and building a unit at the back which we could rely on. It’s a shame it didn’t work out like it should have done at the back as there weren’t many sides scoring more than us.
“We know our limitations budget-wise, but we have done some good business and we’re confident of having a better season.
“We need to be more consistent, and we need to keep more clean sheets. We know we can score goals so if we do that then who knows.”
Eastleigh begin their season at home to Solihull Moors this Saturday.