A port protection circuit protecting at least one port adapted to supply power from a power sourcing equipment, PSE, via an Ethernet cable to a powered device, PD, comprising: a first common mode suppression component, a second common mode suppression component, and at least one rectifier bridge (BR1;BRn), where each of the at least one rectifier bridge is in one-to-one correspondence with a port and with a set of direct current output ends of a power over Ethernet, PoE, control chip, wherein a first input end and a second input end of each rectifier bridge is adapted to be connected to a first direct current output end and a second direct current output end of the corresponding set of direct current output ends of the power over Ethernet, PoE, control chip; the first input end of each rectifier bridge is further adapted to be connected via a central tap of a transformer to charged signal lines (1, 2) of the corresponding port and the second input end of each rectifier bridge is further adapted to be connected via a central tap of a further transformer to further charged signal lines (3, 6) of the corresponding port; one of a first output end or a second output end of each rectifier bridge is adapted to be connected to idle signal lines (4, 5, 7, 8) of the corresponding port, wherein the idle signal lines are uncharged signal lines; an end of the first common mode suppression component is connected to the first output end of each rectifier bridge, and another end of the first common mode suppression component is grounded; and an end of the second common mode suppression is connected to the second output end of each rectifier bridge, and another end of the second common mode suppression component is grounded. a first common mode suppression component, a second common mode suppression component, and at least one rectifier bridge (BR1;BRn), where each of the at least one rectifier bridge is in one-to-one correspondence with a port and with a set of direct current output ends of a power over Ethernet, PoE, control chip, wherein a first input end and a second input end of each rectifier bridge is adapted to be connected to a first direct current output end and a second direct current output end of the corresponding set of direct current output ends of the power over Ethernet, PoE, control chip; the first input end of each rectifier bridge is further adapted to be connected via a central tap of a transformer to charged signal lines (1, 2) of the corresponding port and the second input end of each rectifier bridge is further adapted to be connected via a central tap of a further transformer to further charged signal lines (3, 6) of the corresponding port; one of a first output end or a second output end of each rectifier bridge is adapted to be connected to idle signal lines (4, 5, 7, 8) of the corresponding port, wherein the idle signal lines are uncharged signal lines; an end of the first common mode suppression component is connected to the first output end of each rectifier bridge, and another end of the first common mode suppression component is grounded; and an end of the second common mode suppression is connected to the second output end of each rectifier bridge, and another end of the second common mode suppression component is grounded.