Control apparatus, access control method, and non-transitory recording medium storing a plurality of instructions

1. A control apparatus for controlling access from a communication terminal to an access target server, the control apparatus comprising circuitry configured to:

transmit, to an administrator terminal, screen data for accepting input of requested settings including host information for identifying the access target server and condition information indicating conditions for controlling access to the access target server;

receive the requested settings from the administrator terminal;

store access control settings associating the host information and the condition information based on the received requested settings;

receive an access request to a particular access target server from the communication terminal;

determine whether the communication terminal is permitted to access the particular access target server based on the received access request and a condition indicated by condition information associated with host information for identifying the particular access target server;

transmit destination information indicating a destination of the particular access target server to the communication terminal in response to a determination that the communication terminal is permitted to access the particular access target server; and

transmit a dummy IP address different from the destination information to the communication terminal in response to a determination that the communication terminal is not permitted to access the particular access target server, the dummy IP address being destination information that does not provide access to the particular access target server and that indicates the control apparatus;

transmit access prohibition screen data to the communication terminal in response to receiving the access request to the destination indicated by the dummy IP address from the communication terminal, the access prohibition screen data indicating prohibition of access to the particular access target server,

wherein the control apparatus is a DNS server.

2. The control apparatus of claim 1 , wherein

the condition information indicates a period for restricting access to the access target server.

3. The control apparatus of claim 1 , wherein

the condition information indicates a period for permitting access to the access target server.

4. The control apparatus of claim 1 , wherein the circuitry is further configured to

determine whether the communication terminal is permitted to access the particular access target server additionally based on one of a time the access request transmitted from the communication terminal and a time the access request is received by the control apparatus.

5. An access control method performed by a DNS server, the method comprising;

transmitting, to an administrator terminal, screen data for accepting input of requested settings including host information for identifying an access target server and condition information indicating conditions for controlling access to the access target server;

receiving the requested settings from the administrator terminal;

storing, in a memory, access control settings associating the host information and the condition information based on the received requested settings;

receiving, from a communication terminal, an access request to a particular access target server;

determining whether the communication terminal is permitted to access the particular access target server based on the received access request and a condition indicated by condition information associated with the host information for identifying the particular access target server;

transmitting destination information indicating a destination of the particular access target server to the communication terminal in response to a determination that the communication terminal is permitted to access the particular access target server; and

transmitting a dummy IP address different from the destination information to the communication terminal in response to a determination that the communication terminal is not permitted to access the particular access target server, the dummy IP address being destination information that does not provide access to the particular access target server and that indicates a control apparatus for controlling access from a communication terminal to the access target server; and

transmitting access prohibition screen data to the communication terminal in response to receiving the access request to the destination indicated by the dummy IP address from the communication terminal, the access prohibition screen data indicating prohibition of access to the particular access target server.

6. A non-transitory recording medium storing a plurality of instructions which, when executed by one or more processors of a DNS server, causes the processors to perform an access control method comprising:

transmitting, to an administrator terminal, screen data for accepting input of requested settings including host information for identifying an access target server and condition information indicating conditions for controlling access to the access target server;

receiving the requested settings from the administrator terminal;

storing, in a memory, access control settings associating the host information and the condition information based on the received requested settings;

receiving, from a communication terminal, an access request to a particular access target server; and

determining whether the communication terminal is permitted to access the particular access target server based on the received access request and a condition indicated by condition information associated with the host information for identifying the particular access target server;

transmitting destination information indicating a destination of the particular access target server to the communication terminal in response to a determination that the communication terminal is permitted to access the particular access target server; and

transmitting a dummy IP address different from the destination information to the communication terminal in response to a determination that the communication terminal is not permitted to access the particular access target server, the dummy IP address being destination information that does not provide access to the particular access target server and that indicates a control apparatus for controlling access from a communication terminal to the access target server; and

transmitting access prohibition screen data to the communication terminal in response to receiving the access request to the destination indicated by the dummy IP address from the communication terminal, the access prohibition screen data indicating prohibition of access to the particular access target server.

7. The control apparatus of claim 2 , wherein

the condition information further indicates a network segment corresponding to a physical location.

8. The control apparatus of claim 3 , wherein

the condition information further indicates a network segment corresponding to a physical location.

9. The access control method according to claim 5 , wherein

the condition information indicates a period for restricting access to the access target server and a network segment corresponding to a physical location.

10. The access control method according to claim 5 , wherein

the condition information indicates a period for permitting access to the access target server and a network segment corresponding to a physical location.

11. The non-transitory recording medium according to claim 6 , wherein

the condition information indicates a period for restricting access to the access target server and a network segment corresponding to a physical location.

12. The non-transitory recording medium according to claim 6 , wherein

the condition information indicates a period for permitting access to the access target server and a network segment corresponding to a physical location.