On this page

Troubleshooting

Show all

Help Center/ NAT Gateway/ FAQs/ SNAT Rules/ What Should I Do If My ECS Fails to Access a Server on the Public Network Through a Public NAT Gateway?

What Should I Do If My ECS Fails to Access a Server on the Public Network Through a Public NAT Gateway?

Updated on 2023-05-09 GMT+08:00

View PDF

TCP connection may fail when an ECS accesses a server on the public network through an SNAT rule. Perform the following steps to locate the fault cause:

Run the following command to check whether tcp_tw_recycle is enabled on the remote server:
sysctl -a|grep tcp_tw_recycle

If tcp_tw_recycle is set to 1, tcp_tw_recycle is enabled.
Run the following command to check the number of lost packets of the remote server:
cat /proc/net/netstat | awk '/TcpExt/ { print $21,$22 }'

If ListenDrops is not set to 0, packet loss occurs, that is, the network is faulty.

Troubleshooting

Method 1: Modifying the kernel parameter of the remote server

Run the following command to temporarily modify the parameters (the modification becomes invalid after the server is restarted):
sysctl -w net.ipv4.tcp_tw_recycle=0

Perform the following operations to permanently modify the parameters:
1. Modify the /etc/sysctl.conf file:
  vi /etc/sysctl.conf
  
  Add the following content to the file:
  
  net.ipv4.tcp_tw_recycle=0
2. Press Esc, enter :wq!, and save the file and exit.
3. Run the following command to make the modification take effect:
  sysctl -p

Method 2: Modifying the kernel parameter of the local client

To temporarily modify parameters (the settings become invalid after the local client is restarted), configure the parameter as follows:
sysctl -w net.ipv4.tcp_timestamps=0

Perform the following operations to permanently modify the parameters:
1. Modify the /etc/sysctl.conf file:
  vi /etc/sysctl.conf
  
  Add the following content to the file:
  
  net.ipv4.tcp_timestamps=0
2. Press Esc, enter :wq!, and save the file and exit.
3. Run the following command to make the modification take effect:
  sysctl -p

Parent topic: SNAT Rules

Feedback

Was this page helpful?

Helpful Not helpful

Provide feedback

Thank you very much for your feedback. We will continue working to improve the documentation.

The system is busy. Please try again later.

Which of the following issues have you encountered?

Content is inconsistent with the product UI

Unclear descriptions

Lack of examples or code

Incorrect steps

Can't find what I need

Lack of best practices

Feedback (optional)

0/500

Select at least one type of issue, and enter your comments or suggestions.

Enter a maximum of 500 characters.

Submit Cancel