The file transfer server choices for HMC are shown in Figure 10-14. It is highly recommended to keep IBM Z systems, HMC consoles, and SEs on an isolated  network. This approach prevents SEs initiating FTP connections with outside networks and  applies to all supported file transfer protocols (FTP, FTPS, and SFTP).  With z15 HMC, all FTP connections that originate from the SEs are taken to HMC consoles.  Secure FTP server credentials must be imported to one or more managing HMC consoles.  After the HMC console completes all FTP operations, the HMC console performs the FTP  operation on SE’s behalf and returns the results. The IBM Z platform must be managed by at  least one HMC to allow FTP operations. Before the z14 server generation, the HMC consoles used anonymous cipher suites to  establish console-to-console communication. Anonymous cipher suite is a part of SSL/TLS  protocol and it can be used to create point-to-point connections. Anonymous cipher suite  does not exchange certificates, which can be a security exposure.  Similar to z14, the z15 HMC consoles abandon anonymous cipher suite and implement an  industry standard-based, password-driven cryptography system. The Domain Security  Settings are used to provide authentication and high-quality encryption. Because of these  changes, we now recommend that clients use unique Domain Security settings to provide  maximum security. The new system provides greater security than anonymous cipher suites,  even if the default settings are used.  To allow greater flexibility in password selection, the password limit was increased to 64  characters and special characters are allowed for z15 and z14 installations. If communication  with older systems before z14 is needed, the previous password limits must be followed (6 - 8  characters, only uppercase and number characters allowed). For more information about HMC networks, see the following resources: GLYPH<SM590000> The HMC and SE (Version 2.15.0) console help system, or IBM Knowledge Center  GLYPH<SM590000> IBM Z 8561 Installation Manual for Physical Planning,  GC28-7002  Chapter 10. Hardware Management Console and Support Element  423 Secure console-to-console communications FTP through HMC Figure 10-14 FTP protocols drop-down list