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slackware-current/source/n/network-scripts/README.networking
Patrick J Volkerding 07ac5d43e5 Mon Mar 1 20:10:44 UTC 2021 
a/e2fsprogs-1.46.2-x86_64-1.txz:  Upgraded.
a/etc-15.0-x86_64-14.txz:  Rebuilt.
  /etc/hosts: added IPv6 loopback addresses.
a/hwdata-0.345-noarch-1.txz:  Upgraded.
ap/hplip-3.20.6-x86_64-7.txz:  Rebuilt.
  Fixed desktop file to show category and icon properly.
  Thanks to upnort and ArTourter.
d/git-2.30.1-x86_64-3.txz:  Rebuilt.
  Make sure the bash-completion file is installed in the proper location.
  Thanks to Robby Workman.
d/python-setuptools-54.0.0-x86_64-1.txz:  Upgraded.
d/vala-0.50.4-x86_64-1.txz:  Upgraded.
l/imagemagick-7.0.11_2-x86_64-1.txz:  Upgraded.
l/python-pillow-8.1.1-x86_64-1.txz:  Upgraded.
n/network-scripts-15.0-noarch-13.txz:  Rebuilt.
  Well, apparently there was a newer branch of this than the one that was
  sitting in my usual pending queue, so here it is. This also includes some
  additional documentation on the new features. NOTE: In order to use SLAAC
  to configure IPv6, you'll need to have USE_SLAAC[x]="yes" for the interface
  in rc.inet1.conf. This is to ensure that nobody is surprised to find their
  machine fully exposed to the internet - better safe than sorry.
  Thanks to Darren "Tadgy" Austin and Robby Workman.
n/wireless_tools-30.pre9-x86_64-4.txz:  Rebuilt.
  This package contains some updates to rc.wireless and rc.wireless.conf.
  Thanks to Darren "Tadgy" Austin.
xfce/mousepad-0.5.3-x86_64-1.txz:  Upgraded.
2021-03-02 08:59:52 +01:00

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Slackware Network Configuration
===============================
Networking in Slackware is configured by the /etc/rc.d/rc.inet1 script, and the
configuration file /etc/rc.d/rc.inet1.conf. Wireless interfaces are configured
just like any network interface, but accept many more configuration parameters.
The rc.inet1.conf file contains a series of variable array definitions, with
each array index corresponding to a single network interface. This means that
each set of parameters with an index of 0 configure the first interface (since
indexing starts at 0), parameters with an index of 1 configure the second
interface, and so on. Not all parameters need to be set for each type of
interface, or interface number. This is better illustrated with examples,
which you will find in the documentation below.
Starting and Stopping Interfaces
--------------------------------
The way to start networking (configuring all NICs, bringing the interfaces up,
and creating a default route, if required) is by running the command:
/etc/rc.d/rc.inet1 start
This command will configure all networking interfaces which are defined in the
configuration file, and is used at boot time to bring networking up.
The counterpart to this is the:
/etc/rc.d/rc.inet1 stop
command, which will bring all networking to a stop. It is advised to use this
with caution as it can make your host completely inaccessable from the network.
Restarting the whole network (all available network interfaces) and resetting
the default gateway (if set) is done in a similar fashion to starting it:
/etc/rc.d/rc.inet1 restart
And will first deconfigure all interfaces, before bringing them back up - which
is functionally equalivant to a 'stop' and 'start' operation.
More specifically speaking, you can start/stop/restart any network interface on
an individual basis using the commands:
/etc/rc.d/rc.inet1 <interface>_start
/etc/rc.d/rc.inet1 <interface>_stop
/etc/rc.d/rc.inet1 <interface>_restart
where <interface> is the name of an existing network interface (eth0, eth1,
wlan0, etc).
Guided Networking Configuration
-------------------------------
The 'netconfig' script is capable of configuring basic networking parameters for
the first ethernet interface of the system, and writing an annotated
/etc/rc.d/rc.inet1.conf configuration file. 'netconfig' is usually invoked
during installation to configure the first ethernet interface of your freshly
installed system.
'netconfig' is capable of configuring a set of IPv4 and/or IPv6 addresses for an
interface, or setting the interface to be configured using DHCP (both DHCPv4 and
DHCPv6) and IPv6 StateLess Address Auto Configuration (SLAAC). The default
gateways and nameservers can also be configured through the guided interface.
The option to use NetworkManager for interface configuration (instead of
rc.inet1.conf) is also available.
For most users with a single ethernet interface, and simple IP configuration
requirements, 'netconfig' can completely configure the networking sub-system for
you.
Deprecated and New IPv4 Configuration Syntax
--------------------------------------------
With the release of Slackware 15.0, several parameters used in older
rc.inet1.conf configurations have become deprecated and are substituted by a
new, singular, IP parameter for v4 addresses.
Specifically, the following parameters used in previous rc.inet1.conf
configurations to configure IPv4 addresses have become deprecated:
IPADDR[x]=""
NETMASK[x]=""
IPALIASES[x]=""
These parameters should no longer be used in new configurations.
New configurations should use the updated syntax parameter:
IPADDRS[x]=""
which can hold multiple, space delimited, IPv4 addresses with their CIDR
masks in order to configure an interface.
The format for the addresses specified in this new parameter is:
IP-address/mask
For example:
IPADDRS[0]="192.168.0.1/24 10.10.10.10/8"
which would be the equilivant of old syntax:
IPADDR[0]="192.168.0.1"
NETMASK[0]="255.255.255.0"
IPALIASES[0]="10.10.10.10/8"
If a mask (in CIDR notation) is not provided with the IP address in IPADDRS, it
is assumed to be /24 (aka, 255.255.255.0). A warning will also be emitted about
the missing mask.
rc.inet1 is fully backwards compatible with the older syntax - old configuration
files will contiinue to be accepted for the foreseeable future, but 'netconfig'
has been adjusted to output the new syntax.
Notes:
* When DHCP or SLAAC is used to dynamically configure the interface, IP
addresses specified in IPADDRS will be added to the interface as alias IPs.
However, any address specified in IPADDR is *not* added to the interface in
order to maintain backwards semantics with the pre 15.0 rc.inet1.
* Should an rc.inet1.conf contain both the IPADDR and IPADDRS parameters
(without DHCP or SLAAC being in use) the addresses listed in IPADDRS will be
added to the interface after the IPADDR address is set.
Manual Networking Configuration
-------------------------------
FIXME
IPv6
----
Overview
~~~~~~~~
With the new IPv4 syntax detailed above, there is the addition of optional
configuration semantics for IPv6.
The IPv6 capabilities in Slackware 15.0+ are as follows:
* Dual stack. Interfaces can be configured with an IPv4 address or an IPv6
address, or both.
* Each interface can have single or multiple v4 and/or v6 IPs.
* Optional StateLess Address Auto Configuration (SLAAC) of v6 IP addresses,
for quick and easy IPv6 configuration on supported networks.
* DHCPv6 support for server controlled dynamic address configuration.
* Fixed IPv6 addresses configured interfaces.
'netconfig' can be used for guided configuration of all of the above features,
or they can be configured manually using the options below.
IPv6 Parameters
~~~~~~~~~~~~~~~
v6 IPs can be configured via SLAAC, DHCP6 or statically using the following
new options for rc.inet1.conf:
USE_SLAAC[x]="" Allow StateLess Address Auto Configuration of a
(potentially) globally routable v6 IP. With this
parameter set to "yes", the interface's v6 IP will ONLY
be configured via SLAAC, even if Router Advertisment
indicates DHCPv6 is available on the network - if SLAAC
is not available on the network, no IPv6 address will be
assigned.
Since 'dhcpcd' is capable of handling SLAAC as well as
DHCPv6, it is better practice to set USE_DHCP6[x]="yes"
to perform full auto configuration instead.
USE_DHCP6[x]="" Use 'dhcpcd' to configure the interface. This will
bring up the interface using DHCPv6, falling back to
SLAAC (if supported on the network), or will leave the
interface unconfigured after a timeout. When this
parameter is set to "yes", the USE_SLAAC[x] option is
ignored.
This is the preferred option to configure an interface
dynamically - whether the network is setup for DHCPv6 or
SLAAC, 'dhcpcd' will be able to configure the interface.
IP6ADDRS[x]="" The static v6 IP addresses for the interface. This
parameter takes a list of v6 IP addresses and prefix
lengths in CIDR notation, in a space delimited list.
For example: IP6ADDRS[x]="a:b:c:d:e::1/48 1:2:3:4::5/64"
If a prefix length is not given (separated from the IP
address with a /), a length of 64 will be assumed, and
a warning emitted about the unset value.
When either the USE_DHCP6[x] or USE_SLAAC[x] options are
set to "yes", the IP addresses listed in this parameter
are also added to the interface, but only upon sucessful
assigning of the dynamic IP address.
A static gateway can be configured using this parameter:
GATEWAY6="" The default IPv6 gateway for the network. This is a
single IPv6 address in standard format, without a
prefix suffix.
The following lesser used misc options can be used for tailouring of the IPv6
configuration process:
USE_RA[x]="" Normally, unless USE_SLAAC[x]="yes" is set, Router
Advertisment (RA) is disabled for the interface as it
can result in extraneous routes being added to the
routing table. With this option set to "yes", RA
packets will be accepted on the interface even when DHCP
or fixed IP addressing is used, and the routes
advertised by the router will be added to the table.
Conversely, if this parameter is explicitly set to "no",
RA will be disabled at all times - meaning SLAAC cannot
be performed even when USE_SLAAC[x]="yes" is set. The
default (unset) is to enable RA when SLAAC is in use,
and to disable it otherwise.
The use of this parameter should rarely be required as
rc.inet1 will do the right thing.
SLAAC_TIMEOUT[x]="" The time to wait (in seconds) for an interface to be
configured by SLAAC. When unset, the default is 15.
Some networks may require a longer period for the router
to broadcast an advertisement packet on the network, so
may need to increase this value.
Disabling IPv6
~~~~~~~~~~~~~~
For some use cases, where IPv6 support is not required at all, disabling IPv6
may be a better option than leaving the interface unconfigured.
There are two similar methods which can be used to disable IPv6. Both of the
options involve creating (or replacing the content if it already exists in)
the file:
/etc/modprobe.d/ipv6.conf
(which overrides any configuration in the /lib/modprobe.d/ipv6.conf file),
with the content:
alias ipv6 off
alias net-pf-10 off
Or:
install ipv6 /bin/true
install net-pf-10 /bin/true
It is important to disable both the 'ipv6' and 'net-pf-10' modules since the
module can be automatically loaded by either name.
Changes From Previous Behaviour
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* Previous to Slackware 15.0, if the network the host is connecting to is set
up for StateLess Address Auto Configuration (SLAAC), the host would bring up
an interface with a (potentially) globally routable IPv6 address with no
configuration by the user. This has been changed so that all network
configuration must be explicitly enabled. Thus, interfaces will no longer
automatically come up with a valid IPv6 address on networks which support
auto configuration, without enabling the USE_SLAAC[x]="yes" parameter for
the interface. This is a security enhancement.
* Unless RA is explicitly enabled using the USE_RA[x]="yes" option, rc.inet1
now disables RA (via the accept_ra tunable in /proc) for an interface before
trying to add any IPs configured for it. This prevents RA on the network
from automatically adding any routes to the table. When USE_SLAAC[x]="yes"
is set, RA is implicitly re-enabled for the interface (since SLAAC and RA
are usually used together on a network), unless explicitly disabled with
USE_RA[x]="no". This is a change from previous versions of Slackware, which
would auto configure routes without any user intevention. This is a
security enhancement.
Caveats
~~~~~~~
* When being configured with the USE_DHCP[x]="yes" and USE_DHCP6[x]="yes"
parameters for an interface (that is, configured to obtain both a v4 and v6
addresses via DHCP), 'dhcpcd' will only wait until one type of IP is
obtained before backgrounding - it will not wait for both a v4 AND v6 to be
configured. This means there is no way to know if the interface has been
completely configured for both types of IP, as one type will continue to be
sought in the background; but MAY ultimately fail. This is an issue with
the way dhcpcd operates, not an issue with rc.inet1.
Bonding / Link Aggregation
--------------------------
Overview
~~~~~~~~
Bonding (or Link Aggregation) is a teccnique for combining two or more
physical interfaces into a single, logical, interface; a logical interface
which has all the capabilities of a single physical interface.
The Slackware bonding options provide full support for the features offered by
the bonding kernel module, in the familiar Slackware parameter configuration
syntax. Included is the ability to select the bonding mode, easy addition of
interfaces to a bond using a new parameter in rc.inet1.conf, and the setting
of bonding module options via a new, generic, IFOPTS[x] parameter.
At this time 'netconfig' is unable to configure bonded interfaces, so they
must be configured manually with the parameters detailed below.
Bonding Parameters
~~~~~~~~~~~~~~~~~~
Bonded interfaces can be configured via two new bond specific parameters for
use in rc.inet1.conf, plus the new, generic, IFOPTS[x] parameter. The new
bonding parameters are:
BONDNICS[x]="" The space delimited list of interfaces to add to this
bond. The interfaces will be brought up and configured
while bringing up the interface, so do not need to be
previously defined in rc.inet1.conf. A bond can be
created with only 1 interface, but does not become
useful until at least 2 interfaces are configured.
BONDMODE[x]="" This parameter sets the bonding mode for the logical
interface. If not specified when BONDNICS[x] has been
used, the default is 'balance-rr'. See below for a
list of all bonding modes available.
Bonding Modes
~~~~~~~~~~~~~
When a bonded logical interface is created, it needs to operate in a
particular mode. By default that mode is 'balance-rr'. The following modes,
along with details of their functionallity, are available using the kernel
bonding driver:
802.3ad Also known as LACP. This mode requires a switch that
supports an IEEE 802.3ad. The physical interfaces must
share the same speed and duplex settings and form a
logical interface which provides fault tolerance and
load balancing.
active-backup When in this mode only one interface set to active,
while all other interfaces are in the backup state. If
the active interface fails, a backup interface replaces
it as the only active interface in the bond. This mode
only provides fault tolerance, no load balancing.
This mode requires that the 'primary <interface>'
option be configured with the IFOPTS[x]="" parameter.
balance-alb The receiving packets are load balanced through Address
Resolution Protocol (ARP) negotiation. This mode
provides fault tolerance and load balancing.
balance-rr This mode is also known as round-robin mode. Packets
are sequentially transmitted and received through each
interface one by one. This mode provides load
balancing functionality along with fault tolerance.
This is the default mode of operation.
balance-tlb This mode ensures that outgoing traffic is distributed
according to the load on each physical interface. If
one interface fails to receive traffic, another
interface is assigned to the receiving role. This mode
provides fault tolerance and load balancing.
balance-xor The source MAC address uses eXclusive OR (XOR) logic
with the destination MAC address in order to determine
which physical interface the packet should be sent via.
This calculation ensures that the same physical (slave)
interface is selected for each destination host. If the
physical interface to be used is in a failed state, one
of the backup interfaces is used instead. This mode
provides fault tolerance and load balancing.
broadcast All packets are sent to all the physical (slaved)
interfaces at once. This mode provides fault tolerence
but may result in duplicate packets arriving at the
destination host, assuming they are not screened out by
networking hardware.
Bonding Options
~~~~~~~~~~~~~~~
Bonding specific options can be set using the the IFOPTS[x]="" paramter (which
takes a pipe (|) delimited list of options) for the interface being
configured. The following are the most useful options (but not an exhaustive
list - see "Further Reading" below for more information) which can be set:
lacp_rate This option specifies the rate at which the host will
ask the switch to transmit LACPDU packets in 802.3ad
mode. Possible values are:
slow Transmit LACPDUs every 30 seconds.
fast Transmit LACPDUs every 1 second.
The default is slow, but fast is recommended for rapid
recovery after a physical link failure.
miimon Specifies the MII link monitoring frequency in
milliseconds. This determines how often the link state
of each physical (slaved) interface is checked for link
failures. A value of zero disables MII link monitoring,
but this is NOT advised. A value of 100 is a good
starting point. The default value is 0, so be sure to
set this option with ALL bonding modes.
primary The physical (slave) interface (eth0, eth1, etc) which
is to be used as the primary interface. The specified
interface will always be the active slave while it is
available. Only when the primary interface is off-line
will alternate interfaces be used. This is useful when
one interface is preferred over another (e.g. when one
interface has higher throughput than another). This
option is only valid for "active-backup", "balance-tlb",
and "balance-alb" bonding modes.
xmit_hash_policy Selects the transmit hash policy to use for interface
selection in "balance-xor", "802.3ad", and "balance-tlb"
bonding modes. Possible values are:
layer2 Use eXclusive OR (XOR) of source and
destination MAC addresses and packet
type ID fields to generate the hash.
This algorithm will place all traffic
to a particular destination on the
same phydivsl (slave) interface.
layer2+3 Use a combination of layer2 and
layer3 protocol information (MAC
addresses and IP addresses) to
generate the hash. This algorithm
will place all traffic to a particular
destination on the same physical
(slave) interface. This policy is
intended to provide a more balanced
distribution of traffic than layer2
alone.
layer3+4 This policy uses upper layer protocol
information, when available, to
generate the hash. This allows for
traffic to a particular destination to
span multiple physical (slave)
interfaces, although a single
connection will not span multiple
slaves.
The default value is layer2. Additional (lesser used)
policies are available - see the "Further Reading"
section below for further details.
Caveats
~~~~~~~
* The IFOPTS[x]="" parameter should always include the 'miimon' option - not
using this option will result in network degradation.
* In "active-backup" mode, the "primary" option should also always be
supplied.
* When using "802.3ad" mode, set "lacp_rate fast" for faster recovery from an
interface failure. In other modes, the 'xmit_hash_policy' should be set.
Examples
~~~~~~~~
FIXME: Add examples.
Further Reading
~~~~~~~~~~~~~~~
Full documentation of the bonding layer is available in the kernel source
documentation at: /usr/src/linux/Documentation/networking/bonding.txt.
VLANs (a.k.a, 802.1q)
---------------------
Overview
~~~~~~~~
Virtual LANs (VLANs) allow the segmentation of physical networks into
multiple, isolated, private virtual networks, whilst using shared network
switches and hardware.
VLANs work by applying tags to network frames to form virtual private LANs.
In this way, VLANs can keep network applications separate despite being
connected to the same physical network, and without requiring multiple sets of
cabling and networking devices to be deployed.
In essence, a VLAN is a collection of devices or network hosts that
communicate with one another as if they make up a single LAN, but utilising
shared network hardware.
Because VLAN frames are tagged with a VLAN ID, it is possible to 'cherry-pick'
those frames from the network by use of a VLAN interface on the host.
Slackware now allows configuration of such interfaces in order to allow a host
to join a specific VLAN or VLANs. The guided deployment in 'netconfig' has
been updated to support the creation of such VLAN interfaces.
The configuration in rc.inet1.conf for VLANs is a simple modification of the
existing support for declaration of a network interface using the standard
Slackware IFNAME[x] parameter. As shown in the examples below, VLANs
interfaces can be built on top on top of regular, physical, interfaces, or on
top of a bond interface to allow for link aggregation.
The new IFOPT[x] generic interface options parameter can be used to customise
the usage and configuration of the VLAN interfaces, but is not required in a
normal configuration setting.
Exposing VLANs
~~~~~~~~~~~~~~
Configuring VLAN interfaces utilises the standard Slackware networking
configuration syntax in rc.inet1.conf; with setting up an interface as simple
as changing the IFNAME[x]="" parameter.
VLAN interfaces can be configured quite simply in rc.inet1.conf, in the
standard Slackware way of defining an interface. The key to the configuration
is to use the correct IFNAME[x]="" parameter for the underlying physical (or
bond) interface and the tagged VLAN ID that should be exposed. For example:
IFNAME[0]="eth0.10"
IFOPTS[0]=""
IPADDRS[0]="192.168.10.1/24"
The VLAN ID is taken from the full interface name, as set in the IFNAME[x]
parameter which is comprised of the underlying physical (or bond) interface
name, a period (.) and the VLAN ID to expose. The above example would use the
physical interface 'eth0', and expose the VLAN with ID 10, and configure the
interface with the IPv4 address 192.168.10.1 with a mask of 24.
IFOPTS[x]="" is a pipe (|) delimited list of VLAN kernel module specific
settings to be applied to the interface. The ip-link(8) man page contains
details of exactly what settings can be used with this option (search for
"VLAN Type Support"). For example:
IFOPTS[x]="protocol 802.1ad | reorder_hdr off"
Under normal circumstances, where a standard VLAN interface is required, no
options need be supplied.
Examples
~~~~~~~~
FIXME: Add examples.
Bridges
-------
Wireless (WiFi) Network Interfaces
----------------------------------
TUN/TAP
-------
Advanced networking configuration
---------------------------------
(stacking interface configs - bond, then VLAN, then bridge)
It is also possible to use a bond as the underlying interface, which allows
link aggregated VLAN interfaces to be created for network redundancy. For
example:
IFNAME[0]="bond0"
BONDNICS[0]="eth0 eth1"
BONDMODE[0]="active-backup"
IFOPTS[0]="miimon 100 | primary eth0"
IFNAME[1]="bond0.5"
IFNAME[2]="br0"
BRNICS[2]="bond0.5"
IPADDRS[2]="192.168.5.10/24"
IP6ADDRS[2]="a:b:c:d::1/64"
Would create a bond interface using the eth0 and eth1 physical ethernet
interfaces, in an "active-backup" redundancy configuration with the primary
interface being "eth0", exposing VLAN ID 5 and setting an IPv4 address of
"192.168.5.10" mask "24", plus an IPv6 address of "a:b:c:d::1" prefix "64"
for the interface.
General Caveats
---------------
The network interface definitions are stored in variable arrays. The bash shell has no facilities to retrieve the largest array index used. There-
fore, the rc.inet1 script makes the assumption that array indexes stay below the value of 6. Effectively this means that you can configure up to 6
network interfaces in rc.inet1.conf by default.
If you want to configure more than six network interfaces, you will have to edit the file /etc/rc.d/rc.inet1.conf and change the value `6' in the
line:
#MAXNICS="6"
(at the very bottom of the file) to a value that is larger than the largest index value you use, and uncomment the line.
The /etc/rc.d/rc.wireless script is not meant to be run on its own by the user!
rc.inet1 does not keep a record of how an interface was configured. If the
interface config is changed in rc.inet1.conf from, say, DHCP to static IP,
restarting networking may fail because the previous type of interface config
cannot be stopped (because its type is unknown). In this instance, it is easier
to reboot to start from fresh. However, if reboot is not possible, it may be
required to bring the interface down manually (either by deconfiguring the IPs,
or killing dhcpcd) before trying to restart the interface.
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