Hmmmm, it looks like a variant of the circular MIL-DTL-38999 connectors. Unfortunately they come in hundreds, if not thousands, of variations according to pin count, pin layout, locking mechanism, material, EMC filters, keyway and so on, ad infinitum! Some of the larger electronics distributors (Farnell/Mouser/Digikey) stock some such connectors, but you're more likely to have to go to a specialist distributor. However, it would be worth having a browse on a manufacturer website, like Amphenol, to compare sizes and so on.
Andrew