... commonly used protocols from logical link layer to upper application layer,such as TCP/IP/UDP and so on ... L2TP,IPSEC and GRE)(only for VPN version),DHCP server and client,DDNS (dynamic DNS),firewall,NAT and DMZ ... specifying local and remote IPCan be used as PPP server. Support multi authentication method, such as PAP,CHAP,CHAP ... TFTP upgrade firmwareSupport multi OS, such as WINDOWS, LINUX, SCO UNIX etc