What do I do if the core install on Linux ends with a red line?

Q: What do I do if the core install on Linux ends with a red line?

The core is installed and running on the server, but it has not logged in to the exchange. Do not reinstall: fix the keys and repeat the login. Most often the cause is one of three things: the server's IP is not on the key's whitelist on the exchange (add it to every key), the key does not have the rights it needs (for example, futures), or the key or secret was copied incompletely. If the core is running but the terminal could not reach it, the core's UDP port is blocked by the firewall in the VPS provider's panel.

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