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57f9e5505b
patches/packages/network-scripts-15.0-noarch-19_slack15.0.txz: Rebuilt. This update fixes a bug and adds a new feature: Re-add support for the DHCP_IPADDR parameter from rc.inet1.conf. Expand the help text for DHCP_IPADDR in rc.inet1.conf. Add support for a DHCP_OPTS parameter. Thanks to ljb643 and Darren 'Tadgy' Austin. patches/packages/vim-9.0.1667-x86_64-1_slack15.0.txz: Upgraded. This fixes a rare divide-by-zero bug that could cause vim to crash. In an interactive program such as vim, I can't really see this qualifying as a security issue, but since it was brought up as such on LQ we'll just go along with it this time. :) Thanks to marav for the heads-up. (* Security fix *) patches/packages/vim-gvim-9.0.1667-x86_64-1_slack15.0.txz: Upgraded.
182 lines
8.6 KiB
Text
182 lines
8.6 KiB
Text
IPv6 for Slackware
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==================
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Features
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--------
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* Dual stack. Interfaces can be configured with an IPv4 address or an IPv6
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address, or both.
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* Each interface can have single or multiple v4 and/or v6 IPs. Additional
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v4 IPs are added as 'alias' interfaces, whereas v6 IPs are simply added
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to the interface.
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* Optional StateLess Address Auto Configuration (SLAAC) of v6 IP addresses
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(disabled by default).
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* DHCPv6 support for server controlled address configuration.
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* Fixed IP configuration of IPv6 interfaces.
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Configuration
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-------------
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v6 IPs can be configured via SLAAC, DHCP6 or statically using the following new
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options for rc.inet1.conf:
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USE_SLAAC[x]="" Allow StateLess Address Auto Configuration of a
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(potentially) globally routable v6 IP. With this option
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set to "yes", the interface's v6 IP will ONLY be
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configured via SLAAC, even if RA indicates DHCP6 is
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available on the network - if SLAAC is not available on
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the network, no IPv6 address will be assigned.
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Since dhcpcd is capable of handling SLAAC as well as
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DHCP, it is better practice to set USE_DHCP6[x]="yes" to
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perform full auto configuration instead.
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USE_DHCP6[x]="" Use dhcpcd to configure the interface. This will bring
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up the interface using DHCP6, falling back to SLAAC (if
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configured on the network), or will leave the interface
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unconfigured after a timeout. When this option is set
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to "yes", the USE_SLAAC[x] option is ignored.
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This is the preferred option to configure an interface
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dynamically - whether the network is setup for DHCP6 or
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SLAAC, dhcpcd will be able to configure the interface.
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IP6ADDRS[x]="" The static v6 IP addresses for the interface. This
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option takes a list of v6 IP addresses and prefix
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lengths in CIDR notation, in a space delimited list.
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For example: IP6ADDRS[x]="a:b:c:d:e::1/48 1:2:3:4::5/64"
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If a prefix length is not given (separated from the IP
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address with a /), a length of 64 will be assumed, and
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a warning emitted about the unset value.
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When either the USE_DHCP6[x] or USE_SLAAC[x] options are
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set to "yes", this setting is ignored - dynamic
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configuration takes precedence over fixed IPs in
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Slackware.
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GATEWAY6="" The default IPv6 gateway for the network. This is a
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IPv6 address in standard format.
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The following lesser used misc options have been added for use in rc.inet1.conf:
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USE_RA[x]="" Normally, unless USE_SLAAC[x]="yes" is set, Router
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Advertisment (RA) is disabled for the interface as it
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can result in extraneous routes being added to the
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routing table. With this option set to "yes", RA
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packets will be accepted on the interface even when DHCP
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or fixed IP addressing is used, and the routes
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advertised by the router will be added to the table.
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Conversely, if this option is explicitly set to "no", RA
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will be disabled at all times - meaning SLAAC cannot be
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performed even when USE_SLAAC[x]="yes" is set. The
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default (unset) is to enable RA when SLAAC is in use,
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and to disable it otherwise.
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The use of this option should rarely be required as
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rc.inet1 will do the right thing.
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SLAAC_TIMEOUT[x]="" The time to wait (in seconds) for an interface to be
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configured by SLAAC. When unset, the default is 15.
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Some networks may require a longer period for the router
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to broadcast an advertisement packet on the network.
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Disabling IPv6
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--------------
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For some use cases, where IPv6 support is not required at all, disabling IPv6
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may be a better option than leaving the interface unconfigured.
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There are two similar methods which can be used to disable IPv6. Both of the
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options involve creating (or replacing the content if it already exists) the
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file /etc/modprobe.d/ipv6.conf (which overrides any configuration in the
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/lib/modprobe.d/ipv6.conf file), and making the content as follows:
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alias ipv6 off
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alias net-pf-10 off
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Or:
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install ipv6 /bin/true
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install net-pf-10 /bin/true
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It is important to disable both the 'ipv6' and 'net-pf-10' modules since the
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module can be automatically loaded by each name.
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Changes from previous Slackware versions
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----------------------------------------
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* Previously, if the network the host is connecting to is configured for
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StateLess Address Auto Configuration (SLAAC), the host would bring up an
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interface with a (potentially) globally routable IPv6 address with no
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configuration by the user. This has been changed so that all network
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configuration must be explicitly enabled. Thus, interfaces will no longer
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automatically come up with a valid IPv6 address on networks which support auto
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configuration, without enabling the USE_SLAAC[x]="yes" option for the
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interface. This is a security enhancement.
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* Unless RA is explicitly enabled using the USE_RA[x]="yes" option, rc.inet1 now
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disables RA (via the accept_ra tunable in /proc) for an interface before
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trying to add any IPs configured for it. This prevents RA on the network from
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automatically adding any routes to the table. When USE_SLAAC[x]="yes" is set,
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RA is implicitly re-enabled for the interface (since SLAAC and RA are usually
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used together on a network), unless explicitly disabled with USE_RA[x]="no".
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This is a change from previous versions of Slackware, which would auto
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configure routes. This is a security enhancement in the same vein as above.
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* Interfaces will no longer be brought into the 'up' state unless they are
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actually configured with an IP address. In previous versions, no matter
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whether the interface was assigned an IP (either via DHCP or a fixed IP) or
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not, the interface would be left in the 'up' state after executing 'rc.inet1
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start'. This will no longer happen and is considered a clean-up of the
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previous behaviour.
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* If no NETMASK[x] is set for an interface, rc.inet1 will now assume a
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prefix/netmask of 24 (and will emit a warning). CIDR notation netmasks are now
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recommended (with the leading / as optional), but the old style dotted-quad
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notation is still accepted for IPv4. This is a configuration enhancement.
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* In previous versions, the IP aliases configuration for IPv4 assumed a netmask
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of /32, making the interface only addressable by itself. Now, a netmask of
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/24 is assumed where none is provided in the configuration. This is a bugfix.
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* Sometime during this -current cycle, the call to dhcpcd gained a hard coded -L
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(disable use of IPv4LL addresses as last resort) parameter which effectively
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rendered the DHCP_NOIPV4LL[x] option redundant - the use of -L was not
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contingent upon the value of DHCP_NOIPV4LL[x]. The hard coded -L has been
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removed from the dhcpcd command line, restoring the behaviour of 14.2 and the
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usefulness of the DHCP_NOIPV4LL[x] option.
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Known issues
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------------
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* When being invoked without the -4 or -6 option (that is, when both USE_DHCP[x]
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and USE_DHCP6[x] are set), dhcpcd will only wait until one type of IP is
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obtained before backgrounding - it will not wait for both a v4 AND v6 to be
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configured. This means there is no way to know if the interface has been
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configured for both types of IP, as one type will continue to be sought in the
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background; but may ultimately fail. This is an issue with the way dhcpcd
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operates and not an issue with rc.inet1.
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* Changes in interface configuration type from DHCP to fixed IP or stateless
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will cause an issue where the dhcpcd daemon fails to be stopped during a
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restart or stop/start operation because rc.inet1 is unaware of how an
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interface was previously configured - it can only stop the interface based
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upon its current configuration. This is a by-product of the way the rc.inet1
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script is coded (there is no record kept of the previous configuration type of
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an interface) and is present (but doesn't seem to be documented anywhere) on
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previous versions of Slackware. This particular issue is not specifically
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related to IPv6, but is documented here for completeness.
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* When being killed in if_down(), dhcpcd requires some command line options to
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match those which were used to invoke it - not only does the interface name
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need to match, but also the use of -4/-6. This can cause a problem during a
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restart or stop/start of the interface if the configuration for DHCP has
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changed. This manifests itself in the same way as the issue detailed above
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and is no more serious. In both cases, the end user must kill the dhcpcd
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daemon manually. This issue is caused by the new way dhcpcd is invoked when
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using/not using IPv6.
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Thanks
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------
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* Robby Workman, for the original iproute2 version of rc.inet1 and advice.
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* David Spencer, for advice, debating, and testing the SLAAC implementation.
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--
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Darren 'Tadgy' Austin.
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<darren (at) afterdark.org.uk>
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