Challenge
Veeam Backup & Replication may fail to connect to some Linux servers depending on their firewall configuration.
For example, distributions based on Debian, SLES, or RHEL have default firewall configurations that may block necessary connections.
Cause
Linux OS firewall configuration and/or security rules restrict connections to the required ports.
Solution
Veeam Backup & Replication will attempt to automatically open ports used by the Veeam Data Mover service. However, if that fails, you may need to configure the Linux server's firewall manually. Please review: Adding Linux Servers: Before You Begin for more information.
More Information
Required modules and permissions for Multi-OS FLR and Repository support for Linux
List of ports that Veeam Backup & Replication uses
Redhat KB5494701: How to create its own custom SELinux policy module wisely
