Some browsers require server certificates to use a Subject Alternative Name (SAN) to specify the domains the certificate protects, and no longer support certificate matching based on a server certificate Common Name (CN). SANs enable a single server certificate to protect multiple names; CNs are less well-defined than SANs and can protect only a single domain or all first-level subdomains on a domain. However, if a server certificates contains only a CN, browsers that require a SAN will not allow end users to connect to the requested web resource.The firewall can add a SAN to the impersonation certificate it generates to establish itself as a trusted third-party during SSL decryption. When a server certificate contains only a CN, a firewall performing SSL decryption copies the server certificate CN to the impersonation certificate SAN. The firewall presents the impersonation certificate with the SAN to the client, and the browser is able to support the connection. End users can continue to access the resources they need, and the firewall can decrypt the sessions.

To enable SAN support for decrypted SSL traffic, update the decryption profile attached to the relevant decryption policy: select ObjectsDecryption ProfileSSL DecryptionSSL Forward ProxyAppend Certificate’s CN Value to SAN Extension).