--- name: "rscsi" section: "1" platform: "linux" package: "cdrtools" version: "3.02a09-6" release: "Arch Linux 2026-11-01" platforms: ["linux"] url: "https://new.carta.tech/rscsi" --- # rscsi(1) remote generic SCSI transport protocol server ## NAME rscsi - remote generic SCSI transport protocol server ## SYNOPSIS **/opt/schily/sbin/rscsi** ## DESCRIPTION The **rscsi** command is a remote generic SCSI transport server program. **rscsi** is a program that is run locally on the machine with SCSI devices, it is used by remote programs like [**cdrecord**(1)](/cdrecord/1.md), [**cdda2wav**(1)](/cdda2wav/1.md), [**readcd**(1)](/readcd/1.md), and **sformat**(1) that like to access SCSI devices through an interprocess communication connection via **libscg**. **rscsi** is normally started up with an [**rexec**(3)](/rexec/3.md) or [**rcmd**(3)](/rcmd/3.md) call but it may also be connected via an internal pipe to an [**ssh**(1)](/ssh/1.md) session that was set up by the remote user. The **rscsi** program accepts **scg\_open**, **scg\_close**, **scg\_cmd** and similar requests that are all related to the interface of **libscg**. **rscsi** performs the commands and then responds with a status indication. The **rscsi** program is prepared to be installed as a **user shell** in the passwd file to create remote SCSI specific logins and security checking. All requests are send to the **rscsi** program in ASCII and thus are byte order and machine independent. All responses are send back in ASCII and in one of the following two forms. All successful commands (except for the "S" command that sends SCSI commands) have responses of - **A***number\\n* where *number* is the ASCII representation of a decimal number that usually is the return code of the corresponding system call or function. All unsuccessful commands are responded to with - **E***error-number***\\n***error-message***\\n***xerror-len**\\n**xerror-txt* where *error-number* is one of the possible error numbers described in [**intro**(2)](/intro/2.md), and *error-message* is the corresponding error string as retrieved by [**strerror**(3)](/strerror/3.md), *xerror-len* is the length of the additional error text *xerror-txt* and may be 0. In case *xerror-len* is 0, no *xerror-txt* is send. Note that a failed SCSI command that returned SCSI sense data counts as a successful command and does not use the default error format. The **rscsi** protocol implements the following commands: - **V***what***\\n** Return the **version** for several instances of the software in the **rscsi** server. The parameter **what** may have the following values: - **0** Return **SCG\_VERSION** from **libscg** on the **rscsi** server. This returns the version string for the low level SCSI transport adaptation layer. - **1** Return **SCG\_AUTHOR** from **libscg** on the **rscsi** server. This returns the author name for the low level SCSI transport adaptation layer. - **2** Return **SCG\_SCCS\_ID** from **libscg** on the **rscsi** server. This returns the SCCS version string for the low level SCSI transport adaptation layer. - **20** Return **SCG\_KVERSION** from **libscg** on the **rscsi** server. This returns the version of kernel instance of the driver that is underneath the low level SCSI transport adaptation layer. This call may not be supported for all operating systems. This command corresponds to the **scg\_version**(3) function from **libscg**. - **O***device***\\n** Open the specified SCSI *device*. See the description of the **dev=** option in [**cdrecord**(1)](/cdrecord/1.md) for more information on possible values of the *device* parameter. If a device is already open, it is closed before a new open is performed. This command corresponds to the **scg\_open**(3) function from **libscg**. The return value in case of success is 0.\ - **C***device***\\n** Close the currently open device or file. The argument *device* is ignored. This command corresponds to the **scg\_close**(3) function from **libscg**. The return value is the return value from the **scg\_close**(3) function.\ - **D***size***\\n** Set up the maximum DMA size for the currently open SCSI device. The *size* parameter is the desired DMA size in bytes. This command corresponds to the **scg\_bufsize**(3) function from **libscg**. The returned value is the actual DMA size that could be set up. This value may be lower than the *size* parameter.\ - **M***size***\\n** Allocate a buffer suitable for SCSI DMA transfers. This command corresponds to the **scg\_getbuf**(3) function from **libscg**. The returned value is the actual DMA size that could be set up. This value may be lower than the *size* parameter.\ - **F\\n** Free a previously allocated buffer. This command corresponds to the **scg\_freebuf**(3) function from **libscg**. The return value in case of success is 0.\ - **N\\n** Retrieve the maximum permitted value for the SCSI bus number. This command corresponds to the **scg\_numbus**(3) function from **libscg**. The return value is the return value from the **scg\_numbus**(3) function.\ - **B***busno***\\n***chan***\\n** Checks whether there is a SCSI bus with a busnumber that is equal to *busno*. The *chan* parameter is currently ignored. This command corresponds to the **scg\_havebus**(3) function from **libscg**. The return value is the return value from the **scg\_havebus**(3) function.\ - **T***busno***\\n***chan***\\n***target**\\n**lun**\\n*** Set the SCSI target address to *busno*, *target*, *lun*. The parameter *chan* is currently ignored. This command corresponds to the **scg\_settarget**(3) function from **libscg**. The return value is the return value from the **scg\_havebus**(3) function.\ - **I\\n** Retrieve the SCSI initiator ID for the current SCSI bus. This command corresponds to the **scg\_initiator\_id**(3) function from **libscg**. The return value is the return value from the **scg\_initiator\_id**(3) function.\ - **A\\n** Check whether the current target is or may be an ATAPI device. This command corresponds to the **scg\_isatapi**(3) function from **libscg**. The return value is the return value from the **scg\_isatapi**(3) function.\ - **R***what***\\n** Perform a SCSI reset. The parameter *what* may have the following values: - 0 Test whether a SCSI reset is supported as with the **SCG\_RESET\_NOP** parameter. - 1 Perform a SCSI target reset as with the **SCG\_RESET\_TGT** parameter. - 2 Perform a SCSI bus reset as with the **SCG\_RESET\_BUS** parameter. This command corresponds to the **scg\_reset**(3) function from **libscg**. The return value is the return value from the **scg\_reset**(3) function. - **S***count***\\n***flags***\\n*cdb\_len*\\n*sense\_len*\\n*timeout*\\n** Send a SCSI command to the currently selected target. This command takes the following parameters: - **count** The DMA count for this command. If the command is a command that transfers data to the target, the related data is send directly after the SCSI command descriptor block. that is described above. - **flags** The flags that apply to this SCSI command: - **1** Tell the kernel that the SCSI command will transfer data from the target to the host. This corresponds to the flag value **SCG\_RECV\_DATA**. - **2** Tell the kernel to send the SCSI command with disconnect/reconnect enabled. This corresponds to the flag value **SCG\_DISRE\_ENA**. This flag is not supported on all platforms. - **4** Make the kernel silent on SCSI errors. This corresponds to the flag value **SCG\_SILENT**. This flag is not supported on all platforms. - **8** Tell the kernel to retry the SCSI command in case of a retryable SCSI transport error. This corresponds to the flag value **SCG\_CMD\_RETRY**. This flag is not supported on all platforms. - **16** Tell the kernel to send the SCSI command with parity disabled. This corresponds to the flag value **SCG\_NOPARITY**. This flag is not supported on all platforms. - **cdb\_len** The SCSI command descriptor length for this command. The SCSI command descriptor has to be send with the correct length directly after the new line past the **timeout** value. - **sense\_len** The amount of sense data that is expected in return of a failed SCSI command that produces SCSI sense data. - **timeout** The timeout for the SCSI command in seconds. Fractions of a second may be specified by sending a floating point number. The reply for a SCSI command that could be send to the target is: **A***count***\\n***error***\\n*errno*\\n*scb*\\n*sense\_count*\\n** - **count** The DMA count of any data returned from the target. If this count is nonzero, the data is send back directly after the reply block mentioned above. - **error** A SCSI error classification from one of the following values: - **0** No error occurred. This value corresponds to the value **SCG\_NO\_ERROR .** - **1** A retryable error occurred while trying to transport the SCSI command to the target. This value corresponds to the value **SCG\_RETRYABLE .** - **2** A fatal error occurred while trying to transport the SCSI command to the target. This value corresponds to the value **SCG\_FATAL .** - **3** A SCSI timeout occurred. This value corresponds to the value **SCG\_TIMEOUT .** - **errno** Any possible **UNIX errno** value for the SCSI command. - **scb** The SCSI status byte - **sense\_count** The sense count returned for the SCSI command. The SCSI sense data is send back directly after any possible SCSI DMA data received from the target. This command corresponds to the **scg\_cmd**(3) function from **libscg**. The return value is the return value from the **scg\_cmd**(3) function. Any other command causes **rscsi** to exit. ## FILES - /etc/default/rscsi Default values can be set for the following options in /etc/default/rscsi. For example: **DEBUG=**/tmp/rscsi.debug\ **USER=**rscsi\ **ACCESS=**rscsi myhost.mydomain.org 1 -1 3 0 All keywords must be on the beginning of a line. - **DEBUG** If you like to get debug information, set this to a file name where **rscsi** should put debug information. - **USER** The name of a user (local to the RSCSI server) that may use the services of the **rscsi** server. More than one **USER=***name* line is possible. A line **USER=**\* grants access to all users. - **ACCESS** This keyword is followed by six parameters separated by a TAB. The **name** of a user (local to the RSCSI server host) that may use the services of the **rscsi** server followed by the **name of a host** from where operation is granted followed by a **SCSI device** specification that is made of **bus-number** **channel** (ignored for now) **target-id** and **lun** that specify a SCSI device that may be accessed if this **ACCESS** line matches. If one or more entries of the **bus-number** **channel** **target-id** **lun** specification is set to -1, this matches any possible value for the related part of the SCSI device specification. More than one **ACCESS=***name host SCSI-device* line is possible. If standard input of **rscsi** is not a socket from a remote host, **rscsi** will compare the **host entry** from **/etc/default/rscsi** with the following strings: - **PIPE** If **stdin** is a UNIX pipe. If you like to allow remote connections that use the **ssh** protocol, you need to use the word **PIPE** instead of the real hostname in the matching **ACCESS=** line. - **ILLEGAL\_SOCKET** If **getpeername()** does not work for **stdin**. - **NOT\_IP** If **getpeername()** works for **stdin** but is not connected to an internet socket. ## SEE ALSO [**cdrecord**(1)](/cdrecord/1.md), [**cdda2wav**(1)](/cdda2wav/1.md), [**readcd**(1)](/readcd/1.md), **sformat**(1), [**ssh**(1)](/ssh/1.md), [**intro**(2)](/intro/2.md), [**open**(2)](/open/2.md), [**close**(2)](/close/2.md), [**read**(2)](/read/2.md), [**write**(2)](/write/2.md), [**ioctl**(2)](/ioctl/2.md), **getpeername(3)** [**rcmd**(3)](/rcmd/3.md), [**rexec**(3)](/rexec/3.md), [**strerror**(3)](/strerror/3.md) ## DIAGNOSTICS All responses are send to the network connection. They use the form described above. ## NOTES The possibility to create a debug file by calling **rscsi** *file* has been disabled for security reasons. If you like to debug **rscsi** edit **/etc/default/rscsi** and insert a **DEBUG** entry. ## BUGS None known. ## HISTORY The **rscsi** command has been developed by Joerg Schilling in June 2000. ## AUTHOR ``` Joerg Schilling Seestr. 110 D-13353 Berlin Germany ``` Mail bugs and suggestions to: **joerg.schilling@fokus.fraunhofer.de** or **js@cs.tu-berlin.de** or **joerg@schily.isdn.cs.tu-berlin.de**\ ## INTERFACE STABILITY The interfaces provided by **rscsi** are designed for long term stability. As **rscsi** depends on interfaces provided by the underlying operating system, the stability of the interfaces offered by **rscsi** depends on the interface stability of the OS interfaces. Modified interfaces in the OS may enforce modified interfaces in **rscsi**.