Vehicle-mounted Ethernet IP (Internet Protocol) address conflict resolution method and system based on NAT (Network Address Translation)

Abstract

The invention relates to a vehicle-mounted Ethernet IP address conflict solving method and system based on NAT. The system comprises a network stack module NetworkStack, a network daemon process module netd and a network configuration script module. A network stack module NetworkStack monitors a data packet transmitted by a DHCP protocol in a communication process, acquires IP address information provided by a server to the vehicle machine, and judges whether the IP address information conflicts with the IP address information in the vehicle; communicating with a kernel through a network daemon module netd; the network configuration script module uses a packet filtering firewall tool iptables to convert an IP address and a gateway address, uses an address resolution protocol arp related tool to convert an arp request address, and maps the IP address of a network layer into an MAC address of a data link layer. IP addresses are internally converted in combination with an upper-layer NetworkStack module, a middle-layer netd gateway and a plug-in script of the Android, the IP addresses in the system are changed into new configuration information, and when a message is forwarded to the outside, the configuration information is changed back to an original state, so that conflict with a network address in the system is avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of Ethernet IP address conflict resolution method, and in particular relates to a NAT-based vehicle-mounted Ethernet IP address conflict resolution method and system. Background Art

[0002] In the Android vehicle platform, the system does not perform special processing on IP address conflicts by default. The vehicle system memory may contain multiple network types, including wireless WiFi (wlan0 / p2p / hotspot) and Ethernet (veth0 / eth0 / eth1... / usb0 / vlan) wired networks, etc. When networks of different types happen to be assigned to the same IP address segment, the routing of the network with lower priority will fail, causing one of the networks to be unusable.

[0003] Some of the network IP addresses in the car are manually statically configured, while others are dynamically assigned by DHCP. Therefore, there is a possibility of a conflict between the address segment assigned by DHCP and the manually statically configured address segment; in addition, if a wired network (such as USB0) and a wireless network (wifi) are connected at the same time, both networks are assigned IP addresses to the car through the counterpart (such as a router, car tbox, etc.), and both networks need to exist at the same time. If these two IPs are assigned to the same network segment, there will also be a problem that one of the networks with a lower routing priority cannot be used. Currently, the native Android car system does not handle these scenarios.

[0004] Address translation (NAT) when there is an IP address conflict is used in many network scenarios, and it is common to see conflicts between external and internal IP addresses. However, it is rarely used in automotive Ethernet. It mainly moves the reserved network address from 192.168.* to other network segments such as 172.*, but this only reduces the possibility of conflict and does not solve the problem from the fundamental principle. The Android system network module mainly includes the upper-layer java network service, netd acts as the Android gateway, communicates with the kernel, connects the upper layer and the bottom layer, including routing strategies, domain name resolution, firewall strategies, traffic monitoring, etc., and the kernel protocol stack. Assuming that the IP address assigned by the external network conflicts with the existing IP address in the car, all network information configured for the external network needs to be converted, such as dns, ip address, gateway, and arp request.

[0005] Therefore, the present invention provides a method and system for solving the conflict of vehicle-mounted Ethernet IP addresses based on NAT. If some static IP segments need to be built into the vehicle computer, when connecting to certain DCHP networks later, if there is a conflict with the built-in static IP addresses, address conversion is performed to solve the problem that one of the networks cannot access the Internet. If there are wired and wireless networks at the same time, it is necessary to keep the two networks coexisting. If the two networks happen to be divided into the same network segment, address conversion is performed to solve the problem that one of the networks cannot access the Internet. Summary of the invention

[0006] The purpose of the present invention is to provide a method and system for solving the conflict of vehicle Ethernet IP addresses based on NAT, so that if some static IP segments need to be built into the vehicle computer, when connecting to some DCHP networks later, if there is a conflict with the built-in static IP addresses, address conversion is performed to solve the problem that one of the networks cannot access the Internet; and if there are wired and wireless networks at the same time, it is necessary to keep the two networks coexisting at the same time. If the two networks happen to be divided into the same network segment, address conversion is performed to solve the problem that one of the networks cannot access the Internet.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0008] A vehicle Ethernet IP address conflict resolution system based on NAT, comprising a network stack module NetworkStack, a network daemon module netd, and a network configuration script module;

[0009] The network stack module NetworkStack is used to monitor the data packets transmitted by the DHCP protocol in real time during the communication process, obtain the IP address information provided by the server to the vehicle computer, and determine whether the IP address conflicts with the IP address information in the vehicle;

[0010] The network daemon process module netd is used to communicate with the kernel through the network daemon process module netd after being processed by the network stack module NetworkStack of the Java layer, so that the final configuration takes effect in the underlying protocol stack;

[0011] The network configuration script module is used to convert IP addresses and gateway addresses using the packet filtering firewall tool iptables and to convert arp request addresses using address resolution protocol arp related tools, thereby mapping the IP address of the network layer to the MAC address of the data link layer.

[0012] Preferably, when the network stack module NetworkStack monitors the data packets transmitted by the DHCP protocol in real time during the communication process, dns information is added through the network domain name resolution server dnsServers, and the dns address is the same as the gateway address;

[0013] The network stack module NetworkStack also includes an IP client module IpClient, and the IP client module IpClient is used to obtain the IP address information assigned to the vehicle computer by the wifi hotspot.

[0014] Preferably, when the netdIP client module IpClient of the network daemon module netd does not perform address processing, conflict judgment and IP address conversion are performed at the place where the network daemon module netd configures the network card interface to interact with the kernel, and calls the network configuration script related to the packet filtering firewall tool iptables;

[0015] After the network daemon module netd has configured the IP address information related to the network card interface, it performs the relevant configuration of the router static routing command ip route, and calls the relevant configuration script of Arptables to convert the arp request.

[0016] In a second aspect, a method for resolving vehicle Ethernet IP address conflicts based on NAT is provided, which is implemented based on any one of the vehicle Ethernet IP address conflicts based on NAT, and includes the following steps:

[0017] S1: Configure a static Ethernet eth0 in the car with an IP address of 192.168.1.3 to achieve internal LAN communication;

[0018] S2: When the wifi network card wlan0 is turned on to connect to the router or mobile phone hotspot, the IP address assigned to the vehicle computer is 192.168.1.53, the gateway address is 192.168.1.1, and the dns address is the same as the gateway address;

[0019] S3: eth0 and wlan0 are on the same network segment 192.168.1.*. When the priority of wlan0 in the routing table is lower than that of eth0, the data transmitted on the wifi will run on eth0, which will conflict with other IP addresses in the car. The packet filtering firewall tool iptables is used to convert the IP address information of the wifi internally. When the data flows to the car computer, the wifi address is converted to other specified address segments inside the car for processing, so that the address segments of wifi and eth0 are different. When the data flows to the outside, the data is transferred back to the original 192.168.1.53, so that the wifi can be used normally.

[0020] Preferably, in step S3, when the priority of wlan0 in the routing table is lower than that of eth0, and the data transmitted on the wifi will run to eth0, a conflict occurs with other IP addresses in the car. The packet filtering firewall tool iptables or Arptables is used, and the conversion process is performed in combination with the Android native network service.

[0021] Preferably, the packet filtering firewall tool iptables implements control over the entry and exit of network data packets and forwarding, and maintains specified tables and specified chains by default, wherein the NAT table controls the address translation in the data packet, and when data enters, it passes through the packet routing application rule chain PREROUTING or processes the data packet INPUT chain entering the local machine, and when data goes out, it passes through the OUTPUT chain that filters all data packets generated by the local machine or processes the data packet POSTROUTING chain that is about to leave the local machine.

[0022] Preferably, when address conflicts are converted, the DNS is directly replaced by the public domain name of 114.114.114.114 from 192.168.XX.1; the IP address information is internally changed from 192.168.XX. to 172.16.XX., and the source address of the INPUT chain for processing data packets entering the local machine during communication remains unchanged at 192.168.XX, and the destination address is changed to 172.16.XX; the source address of the POSTROUTING chain for processing data packets about to leave the local machine is changed to 172.16.XX, and the destination address is 192.168.XX. When data is inbound and outbound, IP address conflicts are avoided by maintaining two sets of IP address information.

[0023] Preferably, the original DNS address is 192.168.XX.1, which is the same as the gateway, and is resolved by the DNS domain name service of the router or mobile phone, and is replaced with 114.114.114.114, and resolved by the public domain name 114.

[0024] Preferably, data transmission on the IP address is converted by the filtering firewall tool iptables to process the INPUT chain of data packets entering the local machine and the POSTROUTING chain of data packets about to leave the local machine. The outbound and inbound data have two sets of IP addresses to avoid conflicts between the internal and static IP addresses on eth0.

[0025] Preferably, the conversion of the arp request is based on the arp request and reply message of the specific source IP, and the MAC address is updated to the arp table entry of the specific source IP and the specific destination IP address, wherein the specific source IP address and the destination IP address are IP addresses after address conversion.

[0026] The beneficial effects of the present invention include:

[0027] The NAT-based vehicle Ethernet IP address conflict resolution method and system provided by the present invention include a network stack module NetworkStack, a network daemon module netd, and a network configuration script module; the network stack module NetworkStack monitors the data packets transmitted by the DHCP protocol during the communication process, obtains the IP address information provided by the server to the vehicle computer, and determines whether it conflicts with the IP address information in the vehicle; communicates with the kernel through the network daemon module netd; the network configuration script module uses the packet filtering firewall tool iptables to convert the IP address and the gateway address and uses the address resolution protocol arp related tools to convert the arp request address, and maps the IP address of the network layer to the MAC address of the data link layer. Combined with the Android upper-layer NetworkStack module, the middle-layer netd gateway and the plug-in script perform internal conversion on the IP address, and these IP addresses become new configuration information inside the system. When the message is forwarded to the outside, these configuration information changes back to the original state to avoid conflicts with the network address in the system.

[0028] First, when each ECU counterpart in the Ethernet topology, including the vehicle system itself, already has a large number of processes and applications using static IPs on the 192.168. network segment, changing the IP address will be a huge workload, and the present invention uses this address conversion solution to save this workload.

[0029] Secondly, when the vehicle system is connected to a tbox, the tbox dynamically assigns an IP address to the vehicle through Ethernet, and then the vehicle is connected to wifi. It is necessary to keep wifi and tbox coexisting at the same time. WiFi and tbox cannot communicate in advance. When the IP address given to the vehicle is on the same network segment, the network with low routing priority will fail. The present invention solves the problem of failure of the network with low routing priority through address conversion.

[0030] Finally, NAT processing is performed when IP address conflicts occur. This solution combines the Android car system, which not only processes the IP address, but also converts the gateway / dns / arp requests to ensure smooth connection and can be applied to a variety of scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The figure is a schematic diagram of the NAT-based vehicle Ethernet IP address conflict resolution principle of the present invention.

[0032] Figure 2 It is a detailed schematic diagram of the NAT-based vehicle Ethernet IP address conflict resolution principle of the present invention.

[0033] Figure 3 A schematic flow chart of a NAT-based vehicle Ethernet IP address conflict resolution method of the present invention. DETAILED DESCRIPTION

[0034] The following is combined with Figure 1 to Figure 3 The present invention is further described in detail:

[0035] Example 1

[0036] A vehicle Ethernet IP address conflict resolution system based on NAT, including a network stack module NetworkStack, a network daemon module netd, and a network configuration script module. The network stack module NetworkStack is used to monitor the data packets transmitted by the DHCP protocol in the communication process in real time, obtain the IP address information provided by the server to the vehicle computer, and judge the IP address to see if it conflicts with the IP address information in the vehicle. The Android upper network stack module NetworkStack will monitor the DHCP packet and obtain the IP address information provided to the vehicle computer by the server, such as the mobile phone hotspot, and judge the IP address here to see if it conflicts with the IP address information in the vehicle.

[0037] The network daemon module netd is used to communicate with the kernel through a series of processes after being processed by the network stack module NetworkStack of the Java layer, so that the final configuration takes effect in the underlying protocol stack. The network configuration script module is used to convert the IP address and gateway address using the packet filtering firewall tool iptables and convert the arp request address using the address resolution protocol arp related tools, and map the IP address of the network layer to the MAC address of the data link layer.

[0038] In this embodiment, when the network stack module NetworkStack monitors the data packets transmitted by the DHCP protocol in real time during the communication process, dns information is added through the network domain name resolution server dnsServers, and the dns address is the same as the gateway address. The network stack module NetworkStack also includes an IP client module IpClient, and the IP client module IpClient is used to obtain the IP address information assigned to the car computer by the wifi hotspot. Here, when processing the dhcp Packet, dns information will be added through dnsServers. The dns address is generally the same as the gateway address, such as 192.168.1.1, which can be replaced with some public domain names, such as 114.114.114.114. The IpClient module of NetworkStack can obtain the IP address information assigned to the car computer by the wifi hotspot, and address replacement is an option here.

[0039] When the netdIP client module IpClient of the network daemon module netd does not perform address processing, conflict judgment and IP address conversion are performed at the place where the network daemon module netd configures the network card interface to interact with the kernel, and the network configuration script related to the packet filtering firewall tool iptables is called. If address processing has not been performed in the IpClient of NetworkStack before, conflict judgment and IP address conversion can be performed at the place where netd configures the network card (interface) to interact with the kernel, and the network configuration script related to iptables is called. After netd configures the IP address information related to the interface, it will perform routing ip route related configuration, and at this time call Arptables and other related configuration scripts to convert the arp request.

[0040] After the network daemon module netd has configured the IP address information related to the network card interface, it performs the relevant configuration of the router static routing command ip route, and calls the relevant configuration script of Arptables to convert the arp request.

[0041] Example 2

[0042] Based on the real-time example 1, a NAT-based vehicle Ethernet IP address conflict resolution method is implemented based on any one of the NAT-based vehicle Ethernet IP address conflict resolution systems, see Figure 1-Figure 3 , including the following steps:

[0043] S1: Configure a static Ethernet eth0 in the car with an IP address of 192.168.1.3 to achieve internal LAN communication;

[0044] S2: When the wifi network card wlan0 is turned on to connect to the router or mobile phone hotspot, the IP address assigned to the vehicle computer is 192.168.1.53, the gateway address is 192.168.1.1, and the dns address is the same as the gateway address;

[0045] S3: eth0 and wlan0 are on the same network segment 192.168.1.*. When the priority of wlan0 in the routing table is lower than that of eth0, the data transmitted on the wifi will run on eth0, which will conflict with other IP addresses in the car. The packet filtering firewall tool iptables is used to convert the IP address information of the wifi internally. When the data flows to the car computer, the wifi address is converted to other specified address segments inside the car for processing, so that the address segments of wifi and eth0 are different. When the data flows to the outside, the data is transferred back to the original 192.168.1.53, so that the wifi can be used normally.

[0046] In the prior art, most solutions are to change the static IP address on 192.168. to the 172.* network segment, which reduces the probability of IP address conflicts, but does not 100% eliminate the possibility of conflicts. In the Ethernet topology structure of the present invention, each ECU counterpart, including the vehicle system itself, already has a large number of processes and applications that use static IPs on the 192.168. network segment. At this time, changing the IP address will result in a huge workload, and the use of this address conversion solution can save this workload. If the vehicle system is connected to a tbox, this tbox is an IP address dynamically assigned to the vehicle through Ethernet, and then the vehicle is connected to wifi, it is necessary to keep wifi and tbox coexisting at the same time. WiFi and tbox cannot communicate in advance. If the IP addresses they give to the vehicle are also on the same network segment, then the network with a low routing priority will fail. This technical solution can also solve this type of problem. NAT processing is performed when IP address conflicts occur. Although it has been applied in many scenarios, this solution combines the Android car system, which not only processes the IP address, but also converts the gateway / dns / arp requests to ensure smooth connection and can be applied to a variety of scenarios.

[0047] Example 3

[0048] On the basis of Example 1 or Example 2, in step S3, when the priority of wlan0 in the routing table is lower than eth0, and the data transmitted on wifi will run to eth0, it will conflict with other IP addresses in the car, and the packet filtering firewall tool iptables or Arptables is used, and combined with the Android native network service for conversion processing. The packet filtering firewall tool iptables implements the control of network data packets entering and exiting the device and forwarding. It maintains the specified table and the specified chain by default. The NAT table controls the address conversion in the data packet. When the data enters, it will pass through the pre-routing rule chain PREROUTING of the data packet or process the INPUT chain of the data packet entering the local machine. When the data goes out, it will filter all the data packets generated by the local machine through the OUTPUT chain or process the data packets about to leave the local machine through the POSTROUTING chain.

[0049] When address conflicts are converted, DNS is directly replaced by the public domain name 114.114.114.114 from 192.168.XX.1; the IP address information is internally changed from 192.168.XX. to 172.16.XX. During communication, the source address of the INPUT chain for processing data packets entering the local machine remains unchanged at 192.168.XX, and the destination address is changed to 172.16.XX. When processing data packets about to leave the local machine, the source address of the POSTROUTING chain is changed to 172.16.XX, and the destination address is 192.168.XX. When data is entering and leaving the machine, IP address conflicts are avoided by maintaining two sets of IP address information.

[0050] In this embodiment, the original DNS address is 192.168.XX.1, which is the same as the gateway. It is resolved by the dns domain name service of the router or mobile phone, replaced with 114.114.114.114, and resolved by the public domain name 114. The data transmission on the IP address is converted by the filtering firewall tool iptables to process the INPUT chain of the data packet entering the local machine and the POSTROUTING chain of the data packet about to leave the local machine. The outbound and inbound data are two sets of IP addresses to avoid conflicts between the internal and static IP addresses on eth0. The conversion of arp requests is based on the arp request and reply messages of a specific source IP, and the MAC address is updated to the arp table entry of the specific source IP and the specific destination IP address. The specific source IP address and destination IP address are IP addresses that have undergone address conversion.

[0051] In summary, the NAT-based vehicle Ethernet IP address conflict resolution method and system provided by the present invention include a network stack module NetworkStack, a network daemon module netd, and a network configuration script module; the network stack module NetworkStack monitors the data packets transmitted by the DHCP protocol during the communication process, obtains the IP address information provided by the server to the vehicle computer, and determines whether it conflicts with the IP address information in the vehicle; communicates with the kernel through the network daemon module netd; the network configuration script module uses the packet filtering firewall tool iptables to convert the IP address and gateway address and uses the address resolution protocol arp related tools to convert the arp request address, and maps the IP address of the network layer to the MAC address of the data link layer. Combined with the Android upper-layer NetworkStack module, the middle-layer netd gateway and the plug-in script perform internal conversion on the IP address, and these IP addresses become new configuration information inside the system. When the message is forwarded to the outside, these configuration information changes back to the original state to avoid conflicts with the network address in the system.

[0052] When each ECU counterpart in the Ethernet topology, including the vehicle system itself, already has a large number of processes and applications using static IPs on the 192.168. network segment, changing the IP address at this time will result in a huge workload, and the present invention can save this workload by using this address conversion scheme. When the vehicle system is connected to a tbox, the tbox is an IP address dynamically assigned to the vehicle through Ethernet, and then the vehicle is connected to wifi, it is necessary to keep wifi and tbox coexisting at the same time. WiFi and tbox cannot communicate in advance. When the IP address given to the vehicle is on the same network segment, the network with a low routing priority will fail. The present invention solves the problem of failure of the network with a low routing priority by address conversion. NAT processing is performed when the IP address conflicts. This solution combines the Android vehicle system, not only processes the IP address, but also converts the gateway / dns / arp request to ensure smooth connection, which can be applied to a variety of scenarios.

Claims

1. A vehicle Ethernet IP address conflict resolution system based on NAT, characterized in that: Including network stack module NetworkStack, network daemon module netd, network configuration script module; The network stack module NetworkStack is used to monitor the data packets transmitted by the DHCP protocol in real time during the communication process, obtain the IP address information provided by the server to the vehicle computer, and determine whether the IP address conflicts with the IP address information in the vehicle; The network daemon process module netd is used to communicate with the kernel through the network daemon process module netd after being processed by the network stack module NetworkStack of the Java layer, so that the final configuration takes effect in the underlying protocol stack; The network configuration script module is used to convert IP addresses and gateway addresses using the packet filtering firewall tool iptables and to convert arp request addresses using address resolution protocol arp related tools, thereby mapping the IP address of the network layer to the MAC address of the data link layer.

2. The NAT-based vehicle Ethernet IP address conflict resolution system according to claim 1, characterized in that: When the network stack module NetworkStack monitors the data packets transmitted by the DHCP protocol in real time during the communication process, the dns information is added through the network domain name resolution server dnsServers, and the dns address is the same as the gateway address; The network stack module NetworkStack also includes an IP client module IpClient, and the IP client module IpClient is used to obtain the IP address information assigned to the vehicle computer by the wifi hotspot.

3. The NAT-based vehicle Ethernet IP address conflict resolution system according to claim 1, characterized in that: When the netdIP client module IpClient of the network daemon module netd does not perform address processing, conflict judgment and IP address conversion are performed at the place where the network daemon module netd configures the network card interface to interact with the kernel, and calls the network configuration script related to the packet filtering firewall tool iptables; After the network daemon module netd has configured the IP address information related to the network card interface, it performs the relevant configuration of the router static routing command ip route, and calls the relevant configuration script of Arptables to convert the arp request.

4. A NAT-based vehicle Ethernet IP address conflict resolution method, implemented based on a NAT-based vehicle Ethernet IP address conflict resolution system according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1: Configure a static Ethernet eth0 in the car with an IP address of 192.168.1.3 to achieve internal LAN communication; S2: When the wifi network card wlan0 is turned on to connect to the router or mobile phone hotspot, the IP address assigned to the vehicle computer is 192.168.1.53, the gateway address is 192.168.1.1, and the dns address is the same as the gateway address; S3: eth0 and wlan0 are on the same network segment 192.168.1.*. When the priority of wlan0 in the routing table is lower than that of eth0, the data transmitted on the wifi will run on eth0, which will conflict with other IP addresses in the car. The packet filtering firewall tool iptables is used to convert the IP address information of the wifi internally. When the data flows to the car computer, the wifi address is converted to other specified address segments inside the car for processing, so that the address segments of wifi and eth0 are different. When the data flows to the outside, the data is transferred back to the original 192.168.1.53, so that the wifi can be used normally.

5. A method for resolving vehicle Ethernet IP address conflicts based on NAT according to claim 4, characterized in that: In step S3, when the priority of wlan0 in the routing table is lower than that of eth0, the data transmitted on the wifi will run to eth0, which will conflict with other IP addresses in the car. The packet filtering firewall tool iptables or Arptables is used in combination with the Android native network service for conversion processing.

6. A method for resolving vehicle Ethernet IP address conflicts based on NAT according to claim 5, characterized in that: The packet filtering firewall tool iptables implements control over the entry and exit of network data packets and their forwarding. By default, it maintains designated tables and designated chains. The NAT table controls the address translation in data packets. When data enters, it will pass through the packet routing application rule chain PREROUTING or process the data packets entering the local machine INPUT chain. When data goes out, it will filter all data packets generated by the local machine through the OUTPUT chain or process the data packets about to leave the local machine through the POSTROUTING chain.

7. The method for resolving vehicle Ethernet IP address conflicts based on NAT according to claim 5, characterized in that: When address conflicts are converted, DNS is directly replaced by the public domain name 114.114.114.114 from 192.168.XX.1; the IP address information is internally changed from 192.168.XX. to 172.16.XX. During communication, the source address of the INPUT chain for processing data packets entering the local machine remains unchanged at 192.168.XX, and the destination address is changed to 172.16.XX. When processing data packets about to leave the local machine, the source address of the POSTROUTING chain is changed to 172.16.XX, and the destination address is 192.168.XX. When data is entering and leaving the machine, IP address conflicts are avoided by maintaining two sets of IP address information.

8. The method for resolving vehicle Ethernet IP address conflicts based on NAT according to claim 6, characterized in that: The original DNS address is 192.168.XX.1, the same as the gateway. It is resolved through the DNS domain name service of the router or mobile phone. It is replaced with 114.114.114.114 and resolved by the public domain name 114.

9. A method for resolving vehicle Ethernet IP address conflicts based on NAT according to claim 8, characterized in that: The data transmission on the IP address is converted by the filtering firewall tool iptables on the INPUT chain that processes the data packets entering the local machine and the POSTROUTING chain that processes the data packets about to leave the local machine. The outbound and inbound data have two sets of IP addresses to avoid conflicts between the internal and static IP addresses on eth0.

10. The method for resolving vehicle Ethernet IP address conflicts based on NAT according to claim 9, characterized in that: The conversion of the arp request is based on the arp request and reply message of the specific source IP, and the MAC address is updated to the arp table entry of the specific source IP and the specific destination IP address, wherein the specific source IP address and the destination IP address are the IP addresses after the address conversion.

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