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Diffstat (limited to 'source/n/network-scripts/README.IPv6')
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diff --git a/source/n/network-scripts/README.IPv6 b/source/n/network-scripts/README.IPv6 new file mode 100644 index 000000000..fe4be5fcf --- /dev/null +++ b/source/n/network-scripts/README.IPv6 @@ -0,0 +1,182 @@ +IPv6 for Slackware +================== + +Features +-------- +* 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. Additional + v4 IPs are added as 'alias' interfaces, whereas v6 IPs are simply added + to the interface. +* Optional StateLess Address Auto Configuration (SLAAC) of v6 IP addresses + (disabled by default). +* DHCPv6 support for server controlled address configuration. +* Fixed IP configuration of IPv6 interfaces. + +Configuration +------------- +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 option + set to "yes", the interface's v6 IP will ONLY be + configured via SLAAC, even if RA indicates DHCP6 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 + DHCP, 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 DHCP6, falling back to SLAAC (if + configured on the network), or will leave the interface + unconfigured after a timeout. When this option 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 DHCP6 or + SLAAC, dhcpcd will be able to configure the interface. + + IP6ADDRS[x]="" The static v6 IP addresses for the interface. This + option 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", this setting is ignored - dynamic + configuration takes precedence over fixed IPs in + Slackware. + + GATEWAY6="" The default IPv6 gateway for the network. This is a + IPv6 address in standard format. + +The following lesser used misc options have been added for use in rc.inet1.conf: + 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 option 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 option 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. + + +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) the +file /etc/modprobe.d/ipv6.conf (which overrides any configuration in the +/lib/modprobe.d/ipv6.conf file), and making the content as follows: + 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 each name. + + +Changes from previous Slackware versions +---------------------------------------- +* Previously, if the network the host is connecting to is configured 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" option 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. This is a security enhancement in the same vein as above. + +* Interfaces will no longer be brought into the 'up' state unless they are + actually configured with an IP address. In previous versions, no matter + whether the interface was assigned an IP (either via DHCP or a fixed IP) or + not, the interface would be left in the 'up' state after executing 'rc.inet1 + start'. This will no longer happen and is considered a clean-up of the + previous behaviour. + +* If no NETMASK[x] is set for an interface, rc.inet1 will now assume a + prefix/netmask of 24 (and will emit a warning). CIDR notation netmasks are now + recommended (with the leading / as optional), but the old style dotted-quad + notation is still accepted for IPv4. This is a configuration enhancement. + +* In previous versions, the IP aliases configuration for IPv4 assumed a netmask + of /32, making the interface only addressable by itself. Now, a netmask of + /24 is assumed where none is provided in the configuration. This is a bugfix. + +* Sometime during this -current cycle, the call to dhcpcd gained a hard coded -L + (disable use of IPv4LL addresses as last resort) parameter which effectively + rendered the DHCP_NOIPV4LL[x] option redundant - the use of -L was not + contingent upon the value of DHCP_NOIPV4LL[x]. The hard coded -L has been + removed from the dhcpcd command line, restoring the behaviour of 14.2 and the + usefulness of the DHCP_NOIPV4LL[x] option. + + +Known issues +------------ +* When being invoked without the -4 or -6 option (that is, when both USE_DHCP[x] + and USE_DHCP6[x] are set), 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 + 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 and not an issue with rc.inet1. + +* Changes in interface configuration type from DHCP to fixed IP or stateless + will cause an issue where the dhcpcd daemon fails to be stopped during a + restart or stop/start operation because rc.inet1 is unaware of how an + interface was previously configured - it can only stop the interface based + upon its current configuration. This is a by-product of the way the rc.inet1 + script is coded (there is no record kept of the previous configuration type of + an interface) and is present (but doesn't seem to be documented anywhere) on + previous versions of Slackware. This particular issue is not specifically + related to IPv6, but is documented here for completeness. + +* When being killed in if_down(), dhcpcd requires some command line options to + match those which were used to invoke it - not only does the interface name + need to match, but also the use of -4/-6. This can cause a problem during a + restart or stop/start of the interface if the configuration for DHCP has + changed. This manifests itself in the same way as the issue detailed above + and is no more serious. In both cases, the end user must kill the dhcpcd + daemon manually. This issue is caused by the new way dhcpcd is invoked when + using/not using IPv6. + + +Thanks +------ +* Robby Workman, for the original iproute2 version of rc.inet1 and advice. +* David Spencer, for advice, debating, and testing the SLAAC implementation. + +-- +Darren 'Tadgy' Austin. +<darren (at) afterdark.org.uk> |