The communication between System Center Operations Manager Management Server and the UNIX/Linux agents are secured with TLS/SSL. UNIX and Linux agents employ Server Authentication certificates (i.e. “agent certificates”) for the TLS/SSL channel and these certificates are signed by an Operations Manager Management Server’s “signing certificate.”

https://blogs.technet.microsoft.com/momteam/2017/03/01/deprecating-sha1-certificates-in-system-center-operations-manager-for-unixlinux-monitoring/