A network device, comprising: at least one processor; and at least one memory including computer program codes; the at least one memory and the computer program codes configured to, with the at least one processor, cause the network device to: receive, from a terminal device in a group of terminal devices, a connection request comprising an identity of the terminal device and a first signature of the terminal device; obtain a group identity of the group of terminal devices based on the identity of the terminal device; determine a group status of the group based on the group identity, the group status relating to historical access of the group of terminal devices to a network; and transmit, to the terminal device, a response to the connection request at least in part based on the group status of the group, wherein the transmitting of the response to the connection request comprises: - obtain the first signature of the terminal device from the connection request; - verify the first signature; - in response to the first signature being successfully verified and the group status indicating that at least one terminal device in the group of terminal devices has successfully accessed to the network previously, transmit, to the terminal device, the response comprising an approval of the connection request; and - in response to the first signature being successfully verified and the group status indicating that the connection request is associated with an initial access of the group of terminal devices to the network, transmit, to the terminal device, the response comprising a second signature of the network device to be verified by the terminal device. at least one processor; and at least one memory including computer program codes; the at least one memory and the computer program codes configured to, with the at least one processor, cause the network device to: receive, from a terminal device in a group of terminal devices, a connection request comprising an identity of the terminal device and a first signature of the terminal device; obtain a group identity of the group of terminal devices based on the identity of the terminal device; determine a group status of the group based on the group identity, the group status relating to historical access of the group of terminal devices to a network; and transmit, to the terminal device, a response to the connection request at least in part based on the group status of the group, wherein the transmitting of the response to the connection request comprises: - obtain the first signature of the terminal device from the connection request; - verify the first signature; - in response to the first signature being successfully verified and the group status indicating that at least one terminal device in the group of terminal devices has successfully accessed to the network previously, transmit, to the terminal device, the response comprising an approval of the connection request; and - in response to the first signature being successfully verified and the group status indicating that the connection request is associated with an initial access of the group of terminal devices to the network, transmit, to the terminal device, the response comprising a second signature of the network device to be verified by the terminal device. receive, from a terminal device in a group of terminal devices, a connection request comprising an identity of the terminal device and a first signature of the terminal device; obtain a group identity of the group of terminal devices based on the identity of the terminal device; determine a group status of the group based on the group identity, the group status relating to historical access of the group of terminal devices to a network; and transmit, to the terminal device, a response to the connection request at least in part based on the group status of the group, wherein the transmitting of the response to the connection request comprises: - obtain the first signature of the terminal device from the connection request; - verify the first signature; - in response to the first signature being successfully verified and the group status indicating that at least one terminal device in the group of terminal devices has successfully accessed to the network previously, transmit, to the terminal device, the response comprising an approval of the connection request; and - in response to the first signature being successfully verified and the group status indicating that the connection request is associated with an initial access of the group of terminal devices to the network, transmit, to the terminal device, the response comprising a second signature of the network device to be verified by the terminal device. - obtain the first signature of the terminal device from the connection request; - verify the first signature; - in response to the first signature being successfully verified and the group status indicating that at least one terminal device in the group of terminal devices has successfully accessed to the network previously, transmit, to the terminal device, the response comprising an approval of the connection request; and - in response to the first signature being successfully verified and the group status indicating that the connection request is associated with an initial access of the group of terminal devices to the network, transmit, to the terminal device, the response comprising a second signature of the network device to be verified by the terminal device.