If your Linux server is opening lots of outgoing network connections, you need to increase local port range. By default range is small. For example a squid proxy server can come under fire if it runs out of ports. Other example includes heavy traffic network servers, like nginx load balancers, LXD vm and more.
How do you install and use rsync to synchronize files and directories from one location (or one server) to another location? – A common question asked by new sys admin.