# ip-netns

## NAME



           ip-netns - process network namespace management
    


## SYNOPSIS



           **ip**[ _OPTIONS_ ] **netns**{ _COMMAND_ | **help**}
    
           **ip netns**[ **list**]
    
           **ip netns add** _NETNSNAME_
    
           **ip netns attach** _NETNSNAME PID_
    
           **ip [-all] netns del**[ _NETNSNAME_ ]
    
           **ip netns set** _NETNSNAME NETNSID_
    
           _NETNSID_ := _auto_ | _POSITIVE-INT_
    
           **ip netns identify**[ _PID_ ]
    
           **ip netns pids** _NETNSNAME_
    
           **ip [-all] netns exec**[ _NETNSNAME_ ] _command_...
    
           **ip netns monitor**
    
           **ip netns list-id**[ target-nsid _POSITIVE-INT_ ] [ nsid _POSITIVE-INT_
                   ]
    


## DESCRIPTION



           A network namespace is logically another copy of the network
           stack, with its own routes, firewall rules, and network devices.
    
           By default a process inherits its network namespace from its
           parent. Initially all the processes share the same default network
           namespace from the init process.
    
           By convention a named network namespace is an object at
           **/var/run/netns/** NAME that can be opened. The file descriptor
           resulting from opening **/var/run/netns/** NAME refers to the specified
           network namespace. Holding that file descriptor open keeps the
           network namespace alive. The file descriptor can be used with the
           setns(2) system call to change the network namespace associated
           with a task.
    
           For applications that are aware of network namespaces, the
           convention is to look for global network configuration files first
           in **/etc/netns/** NAME**/** then in **/etc/**.  For example, if you want a
           different version of **/etc/resolv.conf** for a network namespace used
           to isolate your vpn you would name it
           **/etc/netns/myvpn/resolv.conf.**
    
           **ip netns exec** automates handling of this configuration, file
           convention for network namespace unaware applications, by creating
           a mount namespace and bind mounting all of the per network
           namespace configure files into their traditional location in /etc.
    
           **ip netns list - show all of the named network namespaces**
    
                  This command displays all of the network namespaces in
                  /var/run/netns
    
           **ip netns add NAME - create a new named network namespace**
    
                  If NAME is available in /var/run/netns this command creates
                  a new network namespace and assigns NAME.
    
           **ip netns attach NAME PID - create a new named network namespace**
    
                  If NAME is available in /var/run/netns this command
                  attaches the network namespace of the process PID to NAME
                  as if it were created with ip netns.
    
           **ip [-all] netns delete [ NAME ] - delete the name of a network**
           **namespace(s)**
    
                  If NAME is present in /var/run/netns it is umounted and the
                  mount point is removed. If this is the last user of the
                  network namespace the network namespace will be freed and
                  all physical devices will be moved to the default one,
                  otherwise the network namespace persists until it has no
                  more users. ip netns delete may fail if the mount point is
                  in use in another mount namespace.
    
                  If **-all** option was specified then all the network namespace
                  names will be removed.
    
                  It is possible to lose the physical device when it was
                  moved to netns and then this netns was deleted with a
                  running process:
    
                     $ ip netns add net0
                     $ ip link set dev eth0 netns net0
                     $ ip netns exec net0 SOME_PROCESS_IN_BACKGROUND
                     $ ip netns del net0
    
                  and eth0 will appear in the default netns only after
                  SOME_PROCESS_IN_BACKGROUND will exit or will be killed. To
                  prevent this the processes running in net0 should be killed
                  before deleting the netns:
    
                     $ ip netns pids net0 | xargs kill
                     $ ip netns del net0
    
           **ip netns set NAME NETNSID - assign an id to a peer network**
           **namespace**
    
                  This command assigns a id to a peer network namespace. This
                  id is valid only in the current network namespace.  If the
                  keyword "auto" is specified an available nsid will be
                  chosen.  This id will be used by the kernel in some netlink
                  messages. If no id is assigned when the kernel needs it, it
                  will be automatically assigned by the kernel.  Once it is
                  assigned, it's not possible to change it.
    
           **ip netns identify [PID] - Report network namespaces names for**
           **process**
    
                  This command walks through /var/run/netns and finds all the
                  network namespace names for network namespace of the
                  specified process, if PID is not specified then the current
                  process will be used.
    
           **ip netns pids NAME - Report processes in the named network**
           **namespace**
    
                  This command walks through proc and finds all of the
                  process who have the named network namespace as their
                  primary network namespace.
    
           **ip [-all] netns exec [ NAME ] cmd ... - Run cmd in the named**
           **network namespace**
    
                  This command allows applications that are network namespace
                  unaware to be run in something other than the default
                  network namespace with all of the configuration for the
                  specified network namespace appearing in the customary
                  global locations. A network namespace and bind mounts are
                  used to move files from their network namespace specific
                  location to their default locations without affecting other
                  processes.
    
                  If **-all** option was specified then **cmd** will be executed
                  synchronously on the each named network namespace even if
                  **cmd** fails on some of them. Network namespace name is
                  printed on each **cmd** executing.
    
           **ip netns monitor - Report as network namespace names are added and**
           **deleted**
    
                  This command watches network namespace name addition and
                  deletion events and prints a line for each event it sees.
    
           **ip netns list-id [target-nsid POSITIVE-INT] [nsid POSITIVE-INT] -**
           **list network namespace ids (nsid)**
    
                  Network namespace ids are used to identify a peer network
                  namespace. This command displays nsids of the current
                  network namespace and provides the corresponding iproute2
                  netns name (from /var/run/netns) if any.
    
                  The **target-nsid** option enables to display nsids of the
                  specified network namespace instead of the current network
                  namespace. This **target-nsid** is a nsid from the current
                  network namespace.
    
                  The **nsid** option enables to display only this nsid. It is a
                  nsid from the current network namespace. In combination
                  with the **target-nsid** option, it enables to convert a
                  specific nsid from the current network namespace to a nsid
                  of the **target-nsid** network namespace.
    


## EXAMPLES



           ip netns list
                  Shows the list of current named network namespaces
    
           ip netns add vpn
                  Creates a network namespace and names it vpn
    
           ip netns exec vpn ip link set lo up
                  Bring up the loopback interface in the vpn network
                  namespace.
    
           ip netns add foo
           ip netns add bar
           ip netns set foo 12
           ip netns set bar 13
           ip -n foo netns set foo 22
           ip -n foo netns set bar 23
           ip -n bar netns set foo 32
           ip -n bar netns set bar 33
           ip netns list-id target-nsid 12
                  Shows the list of nsids from the network namespace foo.
           ip netns list-id target-nsid 12 nsid 13
                  Get nsid of bar from the network namespace foo (result is
                  23).
    


* * *