2 base baneling rush is one of the hardest rush to stop as a terran. you basically need to have a siege mode orientated opening to counter it. if not, you need to know its coming and have bunkers BEHIND your rax wall......or else you will die. ST july love to do this rush ALOT.

symptoms, more than 8 lings running around for no reason on the field (pro zergs dont make lings for no reason), not alot of drones at nat and finally save your 2nd 50 mana for a scan.

3 things to note in your scan.
-zerg got 3 tech path to choose in ZvT by the time you throw down your scan, (1) starting his lair, (2) roach warren, (3) baneling nest.
-how many gas had he mined? he should have mined about 600 gas b4 his bust. (100 for ling speed, 50 for b nest, about 400 for banelings)
-see whats the next round of unit coming out, drones or lings.

basically if you didnt see a lair, expect a rush coming.

if you 2 rax bunker rushed him and expo behind it, its coming 90% of the time because thats the best thing a Z can do with his extra lings after fending off your push from a hatch first build.

the biggest bust can be up to 20 banelings, enuf to take down the rax wall, thats why you need bunker behind rax....with that double wall, you wont die no matter what and bunker is free teeheee....

but my knowledge of the game had been lacking behind alot...didnt play for almost a month liao, maybe the meta game is diff now.