The thing uder the nose is : a external fairing for the DISS-7 Doppler navigation radar. All the other Su-22 Fitter Js have it mounted interernally.
The only thing I know about he IFR probes are that they were attached/made by a French company,just 2 were fitted with it. The project was abandoned due to lack of funding. The Su-22s have Israeli SAMP Elisra SPS-20 chaff/flare dispensers.