# FAQ

## Maximum Idle Connection Time for GlobalSSH
It is usually 300 seconds (some forwarding machines may be limited to 90 seconds). If you need to maintain a long connection, enable keepalive on either the client or server side and reduce the probe interval.

## How to Use the GlobalSSH Whitelist Function
This whitelist differs from the firewall whitelist of the origin site and is only used to control the source IP that can access GlobalSSH. In the GlobalSSH management list, click to view details, then on the detail page, edit and add to the whitelist under Basic Information on the left side. Both IPv4 segments and multiple IPv4 addresses are supported.

## GlobalSSH Port is Not Accessible
1) The instance requires one minute of startup time. After exceeding this time, first confirm whether the same port of the origin site can be connected;

2) In the GlobalSSH instance detail page, check the access whitelist. If there is a whitelist configured, only IPs listed in the whitelist can connect;

3) From Mainland China, Ping the GlobalSSH domain name. If it can Ping through, try telnetting the GlobalSSH domain name and port to see if it can connect (provide us if it cannot connect); if it cannot Ping through, please dig the GlobalSSH domain name and provide us with the results.