nsenter Man page

NSENTER(1) User Commands NSENTER(1)

NAME

nsenter – run program with namespaces of other processes

SYNOPSIS

nsenter [options] [program [arguments]]

DESCRIPTION

Enters the namespaces of one or more other processes and then executes
the specified program. Enterable namespaces are:

mount namespace
Mounting and unmounting filesystems will not affect the rest of
the system (CLONE_NEWNS flag), except for filesystems which are
explicitly marked as shared (with mount –make-shared; see /proc
/self/mountinfo for the shared flag).

UTS namespace
Setting hostname or domainname will not affect the rest of the
system. (CLONE_NEWUTS flag)

IPC namespace
The process will have an independent namespace for System V mes‐
sage queues, semaphore sets and shared memory segments. (CLONE_
NEWIPC flag)

network namespace
The process will have independent IPv4 and IPv6 stacks, IP rout‐
ing tables, firewall rules, the /proc/net and /sys/class/net
directory trees, sockets, etc. (CLONE_NEWNET flag)

PID namespace
Children will have a set of PID to process mappings separate
from the nsenter process (CLONE_NEWPID flag). nsenter will fork
by default if changing the PID namespace, so that the new pro‐
gram and its children share the same PID namespace and are visi‐
ble to each other. If –no-fork is used, the new program will
be exec’ed without forking.

user namespace
The process will have a distinct set of UIDs, GIDs and capabili‐
ties. (CLONE_NEWUSER flag)

See clone(2) for the exact semantics of the flags.

If program is not given, then “${SHELL}” is run (default: /bin/sh).

OPTIONS

-t, –target pid
Specify a target process to get contexts from. The paths to the
contexts specified by pid are:

/proc/pid/ns/mnt the mount namespace
/proc/pid/ns/uts the UTS namespace
/proc/pid/ns/ipc the IPC namespace
/proc/pid/ns/net the network namespace
/proc/pid/ns/pid the PID namespace
/proc/pid/ns/user the user namespace
/proc/pid/root the root directory
/proc/pid/cwd the working directory respectively

-m, –mount[=file] Enter the mount namespace. If no file is specified, enter the
mount namespace of the target process. If file is specified,
enter the mount namespace specified by file.

-u, –uts[=file] Enter the UTS namespace. If no file is specified, enter the UTS
namespace of the target process. If file is specified, enter
the UTS namespace specified by file.

-i, –ipc[=file] Enter the IPC namespace. If no file is specified, enter the IPC
namespace of the target process. If file is specified, enter
the IPC namespace specified by file.

-n, –net[=file] Enter the network namespace. If no file is specified, enter the
network namespace of the target process. If file is specified,
enter the network namespace specified by file.

-p, –pid[=file] Enter the PID namespace. If no file is specified, enter the PID
namespace of the target process. If file is specified, enter
the PID namespace specified by file.

-U, –user[=file] Enter the user namespace. If no file is specified, enter the
user namespace of the target process. If file is specified,
enter the user namespace specified by file. See also the
–setuid and –setgid options.

-G, –setgid gid
Set the group ID which will be used in the entered namespace and
drop supplementary groups. nsenter always sets GID for user
namespaces, the default is 0.

-S, –setuid uid
Set the user ID which will be used in the entered namespace.
nsenter always sets UID for user namespaces, the default is
0.

–preserve-credentials
Don’t modify UID and GID when enter user namespace. The default
is to drops supplementary groups and sets GID and UID to 0.

-r, –root[=directory] Set the root directory. If no directory is specified, set the
root directory to the root directory of the target process. If
directory is specified, set the root directory to the specified
directory.

-w, –wd[=directory] Set the working directory. If no directory is specified, set
the working directory to the working directory of the target
process. If directory is specified, set the working directory
to the specified directory.

-F, –no-fork
Do not fork before exec’ing the specified program. By default,
when entering a PID namespace, nsenter calls fork before calling
exec so that any children will also be in the newly entered PID
namespace.

-Z, –follow-context
Set the SELinux security context used for executing a new
process according to already running process specified by –tar‐
get PID. (The util-linux has to be compiled with SELinux support
otherwise the option is unavailable.)

-V, –version
Display version information and exit.

-h, –help
Display help text and exit.

SEE ALSO

setns(2), clone(2)

AUTHORS
Eric Biederman ⟨biederm@xmission.com⟩
Karel Zak ⟨kzak@redhat.com⟩

AVAILABILITY
The nsenter command is part of the util-linux package and is available
from Linux Kernel Archive ⟨ftp://ftp.kernel.org/pub/linux/utils/util-
linux/⟩.

util-linux June 2013 NSENTER(1)

Ils en parlent aussi

Introducing a *Super* Privileged Container Concept – RHD Blog