In a game of few clear-cut chances Norwich had the better ones with both Iwan Roberts and Darren Kenton unfortunate.
Roberts fired a thumping drive against the bar in the first half from McVeigh's pass, and after the break Kenton's flicked header brought a fine save from Marshall.
Ipswich had the better of the possession over the whole game, and fired in numerous shots but the majority were from distance and posed little threat to Robert Green in the Norwich goal.
Ipswich piled on the pressure as the match moved to towards stoppage time and they felt they should have had a penalty when Hermann Hreidarsson appeared to be barged over in the box.
Referee Paul Durkin rejected that claim, but upheld the next in the fourth extra minute when Adam Drury handled substitute Counago's cross.
Bent struck the post from the spot, Green blocked Darren Ambrose's follow-up, but Spanish Under-21 international Counago was in the right place to fire home from a couple of yards.
Ipswich: Marshall, McGreal, Hreidarsson, Venus, Wright, Ambrose, Holland, Magilton, Clapham, Marcus Bent, Darren Bent. Subs: Pullen, Armstrong, Miller, Counago, Brown.
Norwich: Green, Nedergaard, Mackay, Kenton, Drury, Mulryne, Notman, Holt, Heckingbottom, Roberts, McVeigh. Subs: Nielsen, Emblen, Russell, Easton, Crichton.
Referee: P Durkin (Dorset)