Provided by: nbdkit_1.24.1-2ubuntu4_amd64 
NAME
nbdkit-ip-filter - filter clients by IP address, process ID, user ID or group ID
SYNOPSIS
nbdkit --filter=ip PLUGIN [allow=addr[,addr...]]
[deny=addr[,addr...]]
DESCRIPTION
"nbdkit-ip-filter" can allow or deny client connections by their IP address. Usually it
is better to control this outside nbdkit, for example using TCP wrappers or a firewall,
but this filter can be used if these are not available.
nbdkit ≥ 1.24 added the ability to filter clients connecting over Unix domain sockets by
client process ID, user ID and group ID. Also this version added support for filtering
"AF_VSOCK" sockets by peer CID or port.
EXAMPLES
Filter by IP address
nbdkit --filter=ip [...] allow=127.0.0.1,::1 deny=all
Allow clients to connect on the loopback IPv4 or loopback IPv6 address, deny all other
clients.
nbdkit --filter=ip [...] deny=8.0.0.0/8
Allow any client except connections from the IPv4 "8.0.0.0/8" network.
nbdkit --filter=ip [...] allow=anyipv6 deny=all
Allow IPv6 clients to connect from anywhere, deny all other sources.
Filter by Unix domain socket peer
nbdkit -U $tmpdir/sock --filter=ip [...] allow=uid:`id -u` deny=all
Only allow the current user ("id -u") to connect over the socket.
Layer extra security by creating the socket inside a temporary directory only accessible
by the user.
nbdkit -U $tmpdir/sock --filter=ip [...] allow=gid:`id -g` deny=all
Allow anyone in the same group as the current user to connect to the Unix domain socket.
As in the previous example, layer extra security by creating the socket inside a temporary
directory only accessible by the group.
RULES
When a client connects, this filter checks its source address against the allow and deny
lists as follows:
1. If the address matches any in the allow list, permission is granted.
2. If the address matches any in the deny list, permission is denied.
3. Otherwise permission is granted.
If either the "allow" or "deny" parameter is not present then it is assumed to be an empty
list. The order in which the parameters appear on the command line does not matter; the
allow list is always processed first and the deny list second.
The "allow" and "deny" parameters each contain a comma-separated list of any of the
following:
all
any These keywords (which both have the same meaning) match any source.
allipv4
anyipv4
These keywords match any IPv4 address.
allipv6
anyipv6
These keywords match any IPv6 address.
allunix
anyunix
These keywords match any connection over a Unix domain socket.
allvsock
anyvsock
These keywords match any connection over an "AF_VSOCK" socket.
A.B.C.D
This matches the single IPv4 address "A.B.C.D", for example 127.0.0.1.
A.B.C.D/NN
This matches the range of IPv4 addresses "A.B.C.D/NN", for example "192.168.2.0/24" or
"10.0.0.0/8".
A:B:...
This matches the single IPv6 address "A:B:...". The usual IPv6 address
representations can be used (see RFC 5952).
A:B:.../NN
This matches a range of IPv6 addresses "A:B:.../NN".
pid:PID
(nbdkit ≥ 1.24, Linux only)
This matches the process ID "PID", if the client connects over a Unix domain socket.
Note that process IDs are recycled so this alone is not secure enough to ensure that
only a single desired process can connect. However you could use it as an additional
check.
uid:UID
(nbdkit ≥ 1.24)
This matches the numeric user ID "UID", if the client connects over a Unix domain
socket.
gid:GID
(nbdkit ≥ 1.24)
This matches the numeric group ID "GID", if the client connects over a Unix domain
socket.
vsock-cid:CID
vsock-port:PORT
(nbdkit ≥ 1.24)
These match the CID or port number for "AF_VSOCK" sockets.
Not filtered
If neither the "allow" nor the "deny" parameter is given the filter does nothing.
Unix domain sockets and "AF_VSOCK" sockets were always unfiltered in nbdkit ≤ 1.22. In
nbdkit ≥ 1.24 the ability to filter them was added.
Common patterns of usage
Permit known good connections and deny everything else:
nbdkit --filter=ip ... allow=good1,good2,... deny=all
Block troublemakers but allow everything else:
nbdkit --filter=ip ... deny=bad1,bad2,...
PARAMETERS
allow=addr[,...]
Set list of allow rules. This parameter is optional, if omitted the allow list is
empty.
deny=addr[,...]
Set list of deny rules. This parameter is optional, if omitted the deny list is
empty.
FILES
$filterdir/nbdkit-ip-filter.so
The filter.
Use "nbdkit --dump-config" to find the location of $filterdir.
VERSION
"nbdkit-ip-filter" first appeared in nbdkit 1.18.
SEE ALSO
nbdkit(1), nbdkit-exitlast-filter(1), nbdkit-exitwhen-filter(1), nbdkit-limit-filter(1),
nbdkit-filter(3).
AUTHORS
Richard W.M. Jones
COPYRIGHT
Copyright (C) 2019-2020 Red Hat Inc.
LICENSE
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