Note:  For more information, see IBM HiperSockets Implementation Guide , SG24-6816. 

## 3.6.3 Security considerations 

Because HiperSockets often are an isolated network with no exposure outside the IBM LinuxONE CPC, security considerations exist for the use of the HiperSockets VSWITCH Bridge. Bridging a HiperSockets CHPID that is used for secure cross-system traffic within an IBM LinuxONE CPC to an external network connection might be a cause of concern that the secure traffic may be exposed. However, because HiperSockets are a LAN segment, security considerations exist whether they are transmitting data in-memory or over OSA CHPIDs. 

Note:  The HiperSockets-VSWITCH Bridge is not a promiscuous bridge; it does not passively transfer all traffic appearing on the HiperSockets onto the VSWITCH or vice versa. It actively sends only frames with destinations that are unknown on the HiperSockets to the VSWITCH. Likewise, the VSWITCH sends only frames to the HiperSockets for addresses that the HiperSockets registered to the VSWITCH. 

Because of the way the function works, it is not feasible that secure traffic on a HiperSockets CHPID might be exposed by the HiperSockets-VSWITCH Bridge. Consider the following points: 

GLYPH<SM590000> The function copies frames only to destinations that are unknown on the HiperSockets over to the VSWITCH. 

GLYPH<SM590000> The HiperSockets network traffic analyzer (NTA) function, which the only method that is available for tracing or ‘sniffing’ traffic on a HiperSockets, only functions with Linux running natively in the LPAR authorized for NTA. 

The number of HiperSockets networks that are available in an IBM LinuxONE CPC makes it possible that a dedicated HiperSockets virtual network might be used for the HiperSockets VSWITCH Bridge function without any perceived risk to the traffic that is carried on HiperSockets that are in use. 

## 3.7 Remote Spooling Communications Subsystem 

Remote Spooling Communications Subsystem (RSCS) Networking for z/VM is a networking program that enables users on a z/VM system to send messages, files, commands, and jobs to other users within a network. It is an easy way to transfer data files (as spool files) among z/VM systems or other systems, such as, z/OS. It also acts as a print server for remote printers that are attached to other z/VM systems or a Internet Protocol network. Through RSCS, users can send and receive messages, files, issue commands, and print and submit jobs within their networks. 

RSCS can communicate with system nodes that are running under the control of network job entry (NJE) compatible subsystems, such as: 

GLYPH<SM590000> JES2 or JES3 

GLYPH<SM590000> RSCS 

GLYPH<SM590000> VSE/POWER 

GLYPH<SM590000> IBM AS/400fi Communications Utilities 

GLYPH<SM590000> Products that provide NJE functions for Linux or IBM AIXfi 

