RUMP_SP(7)

RUMP_SP(7) | Miscellaneous Information Manual | RUMP_SP(7)

# NAME

`rump_sp` —
rump remote system call support

# DESCRIPTION

The `rump_sp` facility allows clients to attach to a rump kernel server over a socket and perform system calls. While making a local rump system call is faster than calling the host kernel, a remote system call over a socket is slower. This facility is therefore meant mostly for operations which are not performance critical, such as configuration of a rump kernel server.

## Clients

The NetBSD base system comes with multiple preinstalled clients which can be used to configure a rump kernel and request diagnostic information. These clients run as hybrids partially in the host system and partially against the rump kernel. For example, network-related clients will typically avoid making any file system related system calls against the rump kernel, since it is not guaranteed that a rump network server has file system support. Another example is DNS: since a rump server very rarely has a DNS service configured, host networking is used to do DNS lookups.

Some examples of clients include `rump.ifconfig` which configures interfaces, `rump.sysctl` which is used to access the sysctl(7) namespace and `rump.traceroute` which is used to display a network trace starting from the rump kernel.

Also, almost any unmodified dynamically linked application (for example telnet(1) or ls(1)) can be used as a rump kernel client with the help of system call hijacking. See rumphijack(3) for more information.

## Connecting to the server

A remote rump server is specified using an URL. Currently two types of URLs are supported: TCP and local domain sockets. The TCP URL is of the format tcp://ip.address:port/ and the local domain URL is unix://path. The latter can accept relative or absolute paths. Note that absolute paths require three leading slashes.

To preserve the standard usage of the rump clients' counterparts the environment variable `RUMP_SERVER` is used to specify the server URL. To keep track of which rump kernel the current shell is using, modifying the shell prompt is recommended -- this is analogous to the visual clue you have when you login from one machine to another.

## Client credentials and access control

The current scheme gives all connecting clients root credentials. It is recommended to take precautions which prevent unauthorized access. For a unix domain socket it is enough to prevent access to the socket using file system permissions. For TCP/IP sockets the only available means is to prevent network access to the socket with the use of firewalls. More fine-grained access control based on cryptographic credentials may be implemented at a future date.

# EXAMPLES

Get a list of file systems supported by a rump kernel server (in case that particular server does not support file systems, an error will be returned):

    $ env RUMP_SERVER=unix://sock rump.sysctl vfs.generic.fstypes

# SEE ALSO

rump_server(1), rump(3), rumpclient(3), rumphijack(3)

# HISTORY

`rump_sp` first appeared in NetBSD 6.0.

February 7, 2011 | NetBSD 9.4