What is the firewall in TypeII?

Routing is the basic element of data communication networks. It is the process of selecting paths on a network along which packets are sent from a source to a destination. Routes are classified into the following types based on the destination address: -Network segment route: The destination is a network segment. The subnet mask of an IPv4 destination address is less than 32 bits or the prefix length of an IPv6 destination address is less than 128 bits. -Host route: The destination is a host. The subnet mask of an IPv4 destination address is 32 bits or the prefix length of an IPv6 destination address is 128 bits. Routes are classified into the following types based on whether the destination is directly connected to a router: -Direct route: The router is directly connected to the network where the destination is located. -Indirect route: The router is indirectly connected to the network where the destination is located. Routes are classified into the following types based on the destination address type: -Unicast route: The destination address is a unicast address. -Multicast route: The destination address is a multicast address.

Default routes are special routes. Generally, administrators can manually configure default static routes. Default routes can also be generated through dynamic routing protocols, such as OSPF and IS-IS. Default routes are described as follows: To put it in a simple way, default routes are used only when packets to be forwarded do not match any routing entry in a routing table. In a routing table, a default route is the route to network 0.0.0.0 (with the mask 0.0.0.0). You can run the display ip routing-table command to check whether a default route is configured. If the destination address of a packet does not match any entry in the routing table, the packet is sent through a default route. If no default route exists and the destination address of the packet does not match any entry in the routing table, the packet is discarded. An Internet Control Message Protocol (ICMP) packet is then sent, informing the originating host that the destination host or network is unreachable.

NAT traversal on the USG What is IPSec NAT traversal? When a NAT device is deployed between IPSec peers, NAT traversal must be enabled at both ends. Authentication Header (AH) hashes the entire IP packet (including the IP address in the IP header) to authenticate data integrity. If NAT is deployed, the IP address changes after NAT, and the hash values will also change, causing an authentication failure. Therefore, the IPSec tunnel that uses AH cannot traverse the NAT gateway. Encapsulating Security Payload (ESP) hashes the payload only. Therefore, IP address changes will not affect the ESP authentication. ESP is a Layer 3 protocol that has no port. Therefore, ESP cannot apply to Network Address Port Translation (NAPT). To resolve this issue, NAT traversal adds a UDP header to the ESP packet. In transport mode, a standard UDP header is inserted between the IP header of the original packet and the ESP header. In tunnel mode, a standard UDP header is inserted between the new IP header and the ESP header. When an ESP packet traverses a NAT device, the NAT device translates the IP address in the outer IP header and the port in the UDP header. The peer end of the IPSec tunnel processes the translated packet as a common IPSec packet. A UDP header is also inserted between the IP header and the ESP header of the reply packet.

A file system consists of storage media and the files stored on the storage media. You can manage the storage media and the files stored on the storage media.

The licenses of firewalls are classified into the following types: -Commercial license It refers to a license purchased with a formal contract. If you need to use functions or features, or extra resources controlled by a license, you need to purchase a license. The commercial licenses are classified into commercial permanent license and commercial temporary license. In principle, license certificates must be issued for commercial permanent licenses (commercial license for short. If otherwise specified, the commercial licenses mentioned in this document refer to commercial permanent license), and license files are issued as e-copies. Generally, commercial temporary licenses are used in the trial or trial before payment scenario. -Non-commercial license It refers to a license used for non-sales purposes such as internal testing, demonstration, or training. No contract is required. The non-commercial license has a certain use period. In principle, the user period of a non-commercial license cannot exceed three months.