Town did enough to have won the game again after Collin Quaner’s first goal for the Club but had to settle for third successive draw.
The Huddersfield loanee finished from close range to put Blues in front but Forest were level before the break through Molla Wague.
Town had the far better of the second-half and Jon Nolan headed wide, with Kayden Jackson twice denied by Carlos Pantilimon but Blues couldn’t find that elusive second goal.
Matt Pennington was one of five changes to the side that drew at Bristol City in midweek, with the Everton loanee returning from a sickness bug, Cole Skuse joined Teddy Bishop in the heart of midfield.
Former Town favourite Daryl Murphy started for Forest, ex Blues loanee Jack Colback skippering the visitors with assistant manager Roy Keane back at Portman Road for the first time since departing the Club in January 2011.
Quaner, back from injury, gave Blues the perfect start, sliding the ball in from close range on five minutes after excellent work by Gwion Edwards, Murphy responding with a header from a corner drifting wide, the Republic of Ireland international then the architect for a chance for Colback, Pennington doing superbly to make the block 10 yards out.
Joe Lolley cut in from the right but couldn’t get enough on his shot to test Bart Bialkowski, then at the other end slick play involving Alan Judge and James Bree saw a cross come in that just evaded the advancing Quaner.
Forest were level on the half hour, Lolley’s corner was never dealt with, Bialkowski clawed the ball off the line and Wague toe-poked the ball over the line while sitting down in one of the more bizarre goals of the season.
Just as at the City Ground, Lolley was causing problems down Town’s left, Teddy Bishop hacking clear after Colback had threatened inside the box, Murphy heading just over before Town were forced into a change, the injured Skuse replaced by Chalobah.
Jack Robinson’s long throws - aided by the wind - were a source of threat for Forest and Murphy had the ball in the net from the rebound after Bialkowski had saved superbly but the offside flag curtailed any celebrations as the visitors finished the half strongly.
Nolan got the second-half underway with a header straight at Carlos Pantilimon, Edwards almost forcing his way in on goal after Bree had fed the ball into the box, then Chalobah exploding a volley just wide.
Superb play down the right by Edwards saw Yohan Benaloune, then Chalobah showed a deft touch to beat Lolley, his cross taken by the wind into Pantilimon’s grateful hands before Town made a second change with Jackson on for Quaner on the hour.
Pennington hooked the ball over from the edge of the box, Nolan sending a diving header wide after brilliant work down the right by Judge, Forest then making two substitutions with Joao Carvalho and Matty Cash entering the fray.
Bishop stopping the breaking Lolley with a timely challenge, Jackson testing Pantilimon with a left footer, then Nolan flashed a strike into the roof of the net from Judge’s free-kick but referee Keith Stroud had blown his whistle a split second earlier.
Town were indebted to Bialkowski for a double save, first denying Cash and then Murphy from the rebound but Blues maintained the pressure on the visitors and Jackson forced Pantilimon into a save with his feet.
Pantilimon denied Jackson again when the striker got in on goal, Chalobah’s header deflected wide, then it was Pennington’s turn to go close with a header.
Luke Chambers flashed a header wide at the near post from a corner as Town dominated, Jackson going down in the box but no penalty, with Judge’s free-kick deflected wide with the last kick of the game.
Town: Bialkowski, Bree, Chambers, Pennington, Kenlock, Skuse (Chalobah 41), Edwards, Nolan, Bishop (Nsiala 90), Judge, Quaner (Jackson 58) Subs not used: Gerken, Knudsen, Dozzell, El Mizouni.
Forest: Pantilimon, Colback, Murphy, Osborn (Cash 63), Wague, Robinson, Yates (Carvalho 63), Lolley, Darikwa, Pele (Ansarifard 75), Benalouane. Subs not used: Steele, Guedioura, Watson, Milosevic. Booked: Colback.
Att: 16,709