For self-protection one should practise loving-kindness (metta) for the four royal families of snakes:

Virūpakkha

Erāpatha

Chabyāputta

Kaṇhā-gotamaka

It was taught when a monk was bitten by a snake at Sāvatthi. A.ii.72. Cp. Vin.ii.109; SA.ii.144.

Another name for it is the Khandha Paritta.