1IP-NETNS(8)                          Linux                         IP-NETNS(8)
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NAME

6       ip-netns - process network namespace management
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SYNOPSIS

9       ip [ OPTIONS ] netns  { COMMAND | help }
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11       ip netns [ list ]
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13       ip netns add NETNSNAME
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15       ip [-all] netns del [ NETNSNAME ]
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17       ip netns set NETNSNAME NETNSID
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19       ip netns identify [ PID ]
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21       ip netns pids NETNSNAME
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23       ip [-all] netns exec [ NETNSNAME ] command...
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25       ip netns monitor
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27       ip netns list-id
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DESCRIPTION

31       A network namespace is logically another copy of the network stack,
32       with its own routes, firewall rules, and network devices.
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34       By default a process inherits its network namespace from its parent.
35       Initially all the processes share the same default network namespace
36       from the init process.
37
38       By convention a named network namespace is an object at
39       /var/run/netns/NAME that can be opened. The file descriptor resulting
40       from opening /var/run/netns/NAME refers to the specified network names‐
41       pace. Holding that file descriptor open keeps the network namespace
42       alive. The file descriptor can be used with the setns(2) system call to
43       change the network namespace associated with a task.
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45       For applications that are aware of network namespaces, the convention
46       is to look for global network configuration files first in
47       /etc/netns/NAME/ then in /etc/.  For example, if you want a different
48       version of /etc/resolv.conf for a network namespace used to isolate
49       your vpn you would name it /etc/netns/myvpn/resolv.conf.
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51       ip netns exec automates handling of this configuration, file convention
52       for network namespace unaware applications, by creating a mount names‐
53       pace and bind mounting all of the per network namespace configure files
54       into their traditional location in /etc.
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56
57       ip netns list - show all of the named network namespaces
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59              This command displays all of the network namespaces in
60              /var/run/netns
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63       ip netns add NAME - create a new named network namespace
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65              If NAME is available in /var/run/netns/ this command creates a
66              new network namespace and assigns NAME.
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69       ip [-all] netns delete [ NAME ] - delete the name of a network names‐
70       pace(s)
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72              If NAME is present in /var/run/netns it is umounted and the
73              mount point is removed. If this is the last user of the network
74              namespace the network namespace will be freed and all physical
75              devices will be moved to the default one, otherwise the network
76              namespace persists until it has no more users. ip netns delete
77              may fail if the mount point is in use in another mount names‐
78              pace.
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80              If -all option was specified then all the network namespace
81              names will be removed.
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83              It is possible to lose the physical device when it was moved to
84              netns and then this netns was deleted with a running process:
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86                 $ ip netns add net0
87                 $ ip link set dev eth0 netns net0
88                 $ ip netns exec net0 SOME_PROCESS_IN_BACKGROUND
89                 $ ip netns del net0
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91              and eth0 will appear in the default netns only after
92              SOME_PROCESS_IN_BACKGROUND will exit or will be killed. To pre‐
93              vent this the processes running in net0 should be killed before
94              deleting the netns:
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96                 $ ip netns pids net0 | xargs kill
97                 $ ip netns del net0
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99
100       ip netns set NAME NETNSID - assign an id to a peer network namespace
101
102              This command assigns a id to a peer network namespace. This id
103              is valid only in the current network namespace.  If the keyword
104              "auto" is specified an available nsid will be chosen.  This id
105              will be used by the kernel in some netlink messages. If no id is
106              assigned when the kernel needs it, it will be automatically
107              assigned by the kernel.  Once it is assigned, it's not possible
108              to change it.
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111       ip netns identify [PID] - Report network namespaces names for process
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113              This command walks through /var/run/netns and finds all the net‐
114              work namespace names for network namespace of the specified
115              process, if PID is not specified then the current process will
116              be used.
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119       ip netns pids NAME - Report processes in the named network namespace
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121              This command walks through proc and finds all of the process who
122              have the named network namespace as their primary network names‐
123              pace.
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125
126       ip [-all] netns exec [ NAME ] cmd ... - Run cmd in the named network
127       namespace
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129              This command allows applications that are network namespace
130              unaware to be run in something other than the default network
131              namespace with all of the configuration for the specified net‐
132              work namespace appearing in the customary global locations. A
133              network namespace and bind mounts are used to move files from
134              their network namespace specific location to their default loca‐
135              tions without affecting other processes.
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137              If -all option was specified then cmd will be executed syn‐
138              chronously on the each named network namespace even if cmd fails
139              on some of them. Network namespace name is printed on each cmd
140              executing.
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143       ip netns monitor - Report as network namespace names are added and
144       deleted
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146              This command watches network namespace name addition and dele‐
147              tion events and prints a line for each event it sees.
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149
150       ip netns list-id - list network namespace ids (nsid)
151
152              Network namespace ids are used to identify a peer network names‐
153              pace. This command displays nsid of the current network names‐
154              pace and provides the corresponding iproute2 netns name (from
155              /var/run/netns) if any.
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EXAMPLES

159       ip netns list
160              Shows the list of current named network namespaces
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162       ip netns add vpn
163              Creates a network namespace and names it vpn
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165       ip netns exec vpn ip link set lo up
166              Bring up the loopback interface in the vpn network namespace.
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168

SEE ALSO

170       ip(8)
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AUTHOR

174       Original Manpage by Eric W. Biederman
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178iproute2                          16 Jan 2013                      IP-NETNS(8)
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