Your message dated Wed, 10 Jun 2026 17:40:28 +0200 with message-id <aimFbP+zM+30zfO/@rosa.stappers.it> and subject line radvd starts without IP forward enabled has caused the Debian Bug report #701928, regarding radvd: Enforcing IPv6 forwarding in radvd startup script breaks some use cases to be marked as done.
This means that you claim that the problem has been dealt with. If this is not the case it is now your responsibility to reopen the Bug report if necessary, and/or fix the problem forthwith. (NB: If you are a system administrator and have no idea what this message is talking about, this may indicate a serious mail system misconfiguration somewhere. Please contact [email protected] immediately.) -- 701928: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=701928 Debian Bug Tracking System Contact [email protected] with problems
--- Begin Message ---Package: radvd Version: 1:1.8.5-1 Severity: important Tags: ipv6 Hello, I'm setting up an IPv6-only virtual platform on a debian wheezy, with complex networking setup and net namespaces. For doing this, i run a radvd on one of the virtual networks. I experimented on this platform a use case where the constraint of enforcing ipv6 forwarding when radvd starts is harmful. The network where radvd runs is configured with Unique Local Addresses and is not supposed to be used for sending packets outside of the system. This looks like the following: VM1 [ fd00:dead:beef::<EUI64> ] \ VM2 [ fd00:dead:beef::<EUI64> ] --- [ fd00:dead:beef::1 ] Host (forwarding disabled) VM3 [ fd00:dead:beef::<EUI64> ] / This setup is perfectly valid and it is possible to specify in Router Advertisements that the "router" (in the sense of the node that sends router advertisements) should not be considered as a default route. In radvd, it is performed by setting the option "AdvDefaultLifetime" to "0". The hosts are still able to perform SLAAC on this prefix and knows that it is not to be used for default route: root@test:~# ip -6 a show eth0 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qlen 1000 inet6 fd00:dead:beef::5054:ff:fe12:3456/64 scope global dynamic valid_lft 86341sec preferred_lft 14341sec inet6 fe80::5054:ff:fe12:3456/64 scope link valid_lft forever preferred_lft forever root@test:~# ip -6 r fd00:dead:beef::/64 dev eth0 proto kernel metric 256 expires 86285sec fe80::/64 dev eth0 proto kernel metric 256 The RFC is consistent with this behaviour. It states that a node may send Router Advertisements while having its forwarding capabilities disabled, as soon as it sets the Router Lifetime field (AdvDefaultLifetime) to zero. RFC 4861 section 6.2.5: Note that system management may disable a router's IP forwarding capability (i.e., changing the system from being a router to being a host), a step that does not necessarily imply that the router's interfaces stop being advertising interfaces. In such cases, subsequent Router Advertisements MUST set the Router Lifetime field to zero. As a conclusion, i kindly ask you to consider relaxing the constraint of having net.ipv6.conf.all.forwarding enabled. It breaks some use cases were disabling forwarding is intended and legal. Regards. Emmanuel Thierry PS: See below my full radvd configuration interface virbr1 { IgnoreIfMissing off; AdvSendAdvert on; AdvDefaultLifetime 0; prefix fd00:dead:beef::1/64 { AdvOnLink on; AdvAutonomous on; }; RDNSS fd00:dead:beef::1 { }; }; -- System Information: Debian Release: 7.0 APT prefers testing APT policy: (500, 'testing') Architecture: amd64 (x86_64) Kernel: Linux 3.2.0-4-amd64 (SMP w/4 CPU cores) Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8) Shell: /bin/sh linked to /bin/dash Versions of packages radvd depends on: ii adduser 3.113+nmu3 ii libc6 2.13-38 radvd recommends no packages. radvd suggests no packages. -- Configuration Files: /etc/init.d/radvd changed [not included] -- no debconf information
--- End Message ---
--- Begin Message ---Hi, While preparing release 2.21 Jun 10 15:29:15 aantje systemd[1]: Starting radvd.service - Router advertisement daemon for IPv6... Jun 10 15:29:15 aantje radvd[1073]: config file, /etc/radvd.conf, syntax ok Jun 10 15:29:15 aantje radvd[1075]: version 2.21 started Jun 10 15:29:15 aantje radvd[1075]: IPv6 forwarding setting is: 0, should be 1 or 2 Jun 10 15:29:15 aantje radvd[1075]: IPv6 forwarding seems to be disabled, but continuing anyway Jun 10 15:29:15 aantje systemd[1]: Started radvd.service - Router advertisement daemon for IPv6. Hence the To: [email protected] Groeten Geert Stappers Debian Developer Maintainer of radvd -- Silence is hard to parse
--- End Message ---
