Kafka Network Connection Conditions

A client can connect to a Kafka instance in public or private networks. Notes before using a private network:

By default, a client and a Kafka instance are interconnected when they are deployed in a VPC.
If they are not, you need to interconnect them because of isolation among VPCs.

Table 1 lists how a client can connect to a Kafka instance.

**Table 1** Connection modes
Mode	How To Do	Reference
Public access	Enable public access on the Kafka console and configure elastic IPs (EIPs). The client can connect to the Kafka instance through EIPs.	Configuring Kafka Public Access
Public access	Configure port mapping using DNAT. The client can connect to the Kafka instance in a public network.	Accessing Kafka in a Public Network Using DNAT
Private access	A client and a Kafka instance are interconnected when they are deployed in a VPC.	-
	When a client and a Kafka instance are deployed in different VPCs of the same region, connect the client and the Kafka instance across VPCs using a VPC endpoint.	Accessing Kafka Using a VPC Endpoint Across VPCs
	When a client and a Kafka instance are deployed in different VPCs of the same region, interconnect two VPCs using a VPC peering connection.	VPC Peering Connection
	When a client and a Kafka instance are not deployed in the same region, create a cloud connection and load the VPCs that need to communicate with each other to the connection.	Connecting VPCs in the Same Account

Before connecting a client to a Kafka instance, allow accesses for the following security groups.

After a security group is created, its default inbound rule allows communication among ECSs within the security group and its default outbound rule allows all outbound traffic. In this case, you can access a Kafka instance within a VPC, and do not need to add rules according to Table 2.

**Table 2** Security group rules
Direction	Protocol	Port	Source	Description
Inbound	TCP	9094	0.0.0.0/0	Accessing a Kafka instance over a public network (in plaintext)
Inbound	TCP	9092	0.0.0.0/0	Accessing a Kafka instance over a private network within a VPC (in plaintext) Accessing a Kafka instance using a peering connection across VPCs (in plaintext)
Inbound	TCP	9095	0.0.0.0/0	Accessing a Kafka instance over a public network (in ciphertext)
Inbound	TCP	9093	0.0.0.0/0	Accessing a Kafka instance over a private network within a VPC (in ciphertext) Accessing a Kafka instance using a peering connection across VPCs (in ciphertext)
Inbound	TCP	9011	198.19.128.0/17	Accessing a Kafka instance using a VPC endpoint across VPCs (in cipher- or plaintext)
Inbound	TCP	9011	0.0.0.0/0	Accessing a Kafka instance using DNAT (in cipher- or plaintext)