Involved in the transport of maltose and maltodextrins, indispensable for translocation of dextrins containing more than three glucosyl moieties. A hydrophobic path ('greasy slide') of aromatic residues serves to guide and select the sugars for transport through the channel (By similarity). Homotrimer formed of three 18-stranded antiparallel beta-barrels, containing three independent channels. By maltose. Belongs to the porin LamB (TC 1.B.3) family.