First question here on serverfault, so kind of a newbie, all feedback is welcome.
I have a dedicated server running Debian GNU/Linux 8.4 (jessie) with one public IP and multiple additional public IPs assigned to it. Server has two NICs, eth0 and eth1, server main public IP is routed to eth1). All additional public IPs are assigned to alias interfaces (eth1:0, eth1:1, eth1:2 etc) except for 1 IP, which I want to assign to a KVM guest, but in a routed networking configuration (the datacenter does not allow multiple MAC addresses to connect to the switch ports, so I have no option but to use routing instead of bridging).
I have set up the interface aliases, and I can assign the corresponding public IPs to different virtualhosts under Apache 2.4 (through the use of ISPConfig 3 web hosting control panel). The virtualhosts work fine in this configuration. Yet, when I try to add a routed network bridge (vmbr0) and route the KVM guest traffic through it, I lose connectivity and have to reboot the server. After reboot, the server works for some time (minutes), and loses connectivity again. I can't seem to figure out what is wrong.
Note: I have followed the Hetzner guide [https://wiki.hetzner.de/index.php/Netzkonfiguration_Debian/en#Routed_.28brouter.29] on another host system, and the KVM guests work alright. Only difference is the aliased interfaces I also need to have in this case.
I have created the bridge interface with:
brctl addbr vmbr0
prior to restarting networking with
/etc/init.d/networking restart
Network configuration for the host system:
auto lo
iface lo inet loopback
auto eth0
iface eth0 inet manual
auto eth1
iface eth1 inet static
address AAA.AAA.AAA.AAA
netmask 255.255.255.0
gateway AAA.AAA.AAA.1
pointopoint AAA.AAA.AAA.1
auto eth1:1
iface eth1:1 inet static
address BBB.BBB.BBB.BBB
netmask 255.255.255.255
auto eth1:2
iface eth1:2 inet static
address CCC.CCC.CCC.CCC
netmask 255.255.255.255
auto eth1:3
iface eth1:3 inet static
address DDD.DDD.DDD.DDD
netmask 255.255.255.255
auto eth1:4
iface eth1:4 inet static
address EEE.EEE.EEE.EEE
netmask 255.255.255.255
auto eth1:5
iface eth1:5 inet static
address FFF.FFF.FFF.FFF
netmask 255.255.255.255
auto eth1:6
iface eth1:6 inet static
address GGG.GGG.GGG.GGG
netmask 255.255.255.255
auto eth1:7
iface eth1:7 inet static
address HHH.HHH.HHH.HHH
netmask 255.255.255.255
auto eth1:8
iface eth1:8 inet static
address III.III.III.III
netmask 255.255.255.255
auto eth1:9
iface eth1:9 inet static
address JJJ.JJJ.JJJ.JJJ
netmask 255.255.255.255
auto eth1:10
iface eth1:10 inet static
address KKK.KKK.KKK.KKK
netmask 255.255.255.255
# KVM VM routed (bridge) interface for single IPs
auto vmbr0
iface vmbr0 inet static
address AAA.AAA.AAA.AAA
netmask 255.255.255.0
bridge_ports none
bridge_stp off
bridge_fd 0
# up ip route add ip1_goes_here/32 dev vmbr0
# up ip route add ip2_goes_here/32 dev vmbr0
# up ip route add ip3_goes_here/32 dev vmbr0
I haven't yet created the KVM guest machine. Perhaps I should have a running VM and traffic routed to it BEFORE bringing the vmbr0 bridge up for some reason? If I can make this work, I'll add additional KVM guests with additional public IPs assigned to them.
Last thing to add is, this is a server already running some websites, so if what I need can be done and with minimum downtime that'd be great!
Thanks!