It is possible on RHEL systems to disable IPv6 autoconfiguration either
system-wide (in /etc/sysconfig/network) or or specific interface (in that
interface's /etc/sysconfig/network-scripts/ifcfg-* file) using the
IPV6_AUTOCONF=[yes/no] statement.
I have been looking for an equivalent mechanism in SLES, so far without
success. Approaches already tried include adding sysctls to /etc/sysctl,
/etc/sysconfig/network/ifsysctl, and interface-specific ifsysctl files under
/etc/sysconfig/network, as well as specifying these sysctls in that
interface's own ifconfig file.
Speicifcally, {net.ipv6.conf.all.autoconf, net.ipv6.conf.default.autoconf,
net.ipv6.conf.all.accept_ra, net.ipv6.default.accept_ra} when attempting to
control this behavior system-wide, and (for example)
{net.ipv6.conf.eth0.autoconf and net.ipv6.conf.eth0.accept_ra} when
attempting to do so on a per-interface basis.
Depending on the timing of when these configuration files are read an
interpreted during the boot process, however, in all cases either the
attempt to apply the sysctls fails because the ipv6 kernel module hasn't yet
been loaded or the relevant sysfs nodes have not yet been created, or
because the sysctls are applied after the network interface has already been
brought online and accepted a router advertisement and global autoconfigured
IPv6 address as per its default behavior.
Disabling these sysctls and then restarting the network (or a specific
interface) will disable autoconfiguration for that interface, but I have not
been able to do so for the first time the interface comes up after boot.
Also, at least in our environment, restarting a network interface causes it
to fail to re-autoconfigure itself even with all the autoconfiguration
sysctls left "on" - such that the interface will not regain an
autoconfigured IPv6 address until after it the Linux has been rebooted. This
behavior has not been seen on our RHEL systems, so I believe it is a symptom
of something happening within the operating system rather than something in
our network's configuration.
Has anyone on this list successfully disabled IPv6 autoconfiguration at* *boot
time for a SLES system, and if so then what approach did you take to do so?
Also, has anyone else seen (and/or found a way to prevent) the issue I've
encountered with interfaces on SLES failing to regain their autoconfigured
network addresses when they or the network service is restarted without
rebooting the Linux?
Thank you.
- Chris
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