Package: ifupdown Version: 0.8.19 Severity: normal Dear Maintainer,
The following command: /sbin/ifup -a --read-environment tries to bring up some GRE tunnels on my system that are already up. Obviously, this fails. One consequence of that is that the systemd "networking" unit is always marked as failed, so systemd never thinks the network is actually up. The relevant bits of the /etc/network/interfaces.d/* looks as follows: auto tun-up-b_ak iface tun-up-b_ak inet static address 100.64.5.59 netmask 255.255.255.254 pre-up ip tunnel add $IFACE mode gre local 51.X.X.X remote 185.X.X.X ttl 255 post-up ip link set $IFACE mtu 1280 post-down ip tunnel del $IFACE iface tun-up-b_ak inet6 static address 2a03:2260:0:ba::2/64 netmask 64 ifup itself shows the following: $ sudo /sbin/ifup -a --read-environment -v ifup: parsing file /etc/network/interfaces.d/ffrl_gre ifup: parsing file /etc/network/interfaces.d/ffrl_gre~ ifup: parsing file /etc/network/interfaces.d/freifunk ifup: parsing file /etc/network/interfaces.d/general ifup: parsing file /etc/network/interfaces.d/inter_gw /bin/run-parts --exit-on-error --verbose /etc/network/if-pre-up.d run-parts: executing /etc/network/if-pre-up.d/bridge run-parts: executing /etc/network/if-pre-up.d/ethtool ifup: configuring interface tun-up-b_ak=tun-up-b_ak (inet) ip tunnel add $IFACE mode gre local 51.X.X.X remote 185.X.X.X ttl 255 add tunnel "gre0" failed: File exists ifup: failed to bring up tun-up-b_ak /bin/run-parts --exit-on-error --verbose /etc/network/if-up.d run-parts: executing /etc/network/if-up.d/ethtool run-parts: executing /etc/network/if-up.d/mountnfs run-parts: executing /etc/network/if-up.d/openssh-server run-parts: executing /etc/network/if-up.d/openvpn run-parts: executing /etc/network/if-up.d/upstart With exactly the same setup (literally -- this is all automatically deployed), I do not get any errors on our jessie systems. Also the stretch system with a slightly older kernel (4.9.0-3) is not affected. The broken machine has 4.9.0-4-amd64. Kind regards, Ralf