How Do I Configure Port Mapping?

Description

How do I configure public access to the EIP and port on ECS 1 to be automatically redirected to a specific port on ECS 2?

Linux

For example, to redirect port 1080 on ECS 1 to port 22 on ECS 2 with the following configurations:

Private IP address and EIP of ECS 1: 192.168.72.10 and 123.xxx.xxx.456

Private IP address of ECS 2: 192.168.72.20

• Ensure that the desired ports have been enabled on the ECS security group and firewall.
• The operations involve modifying kernel parameters, which may cause kernel instability. Evaluate risks before performing this operation.

1. Log in to Linux ECS 1.
   1. Run the following command to modify the configuration file:

      vi /etc/sysctl.conf

   2. Add net.ipv4.ip_forward = 1 to the file.
   3. Run the following command to complete the modification:

      sysctl -p /etc/sysctl.conf

2. Run the following commands to add rules to the nat table in iptables so that the access to port 1080 on ECS 1 can be redirected to port 22 on ECS 2:

   iptables -t nat -A PREROUTING -d 192.168.72.10 -p tcp --dport 1080 -j DNAT --to-destination 192.168.72.20:22

   iptables -t nat -A POSTROUTING -d 192.168.72.20 -p tcp --dport 22 -j SNAT --to 192.168.72.10

3. Run the following command to log in to port 1080 on ECS 1 for check:

   ssh -p 1080 123.xxx.xxx.456

   Figure 1 Port redirections on Linux
   

   Enter the password to log in to ECS 2 with hostname ecs-inner.

   Figure 2 Logging in to ECS 2