George Dunlap dunlapg@umich.edu writes:
*I* care about the documentation that didn't work, so that other people don't trip over the same thing. :-) If you've walked this path and become frustrated, there are probably a dozen other people who have also walked it and just not said anything.
To give an example:
https://www.centos.org/docs/5/html/5.1/Deployment_Guide/s1-networkscripts-st...
[root@charon ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth0 DEVICE="eth0" BOOTPROTO=none DNS1="192.168.178.20" IPADDR="192.168.1.1" NETMASK="255.255.255.255" NM_CONTROLLED=no ONBOOT="yes" TYPE="Ethernet" UUID="1b645d25-9f66-4335-ba0b-939cdd9f553f"
[root@charon ~]# cat /etc/sysconfig/network-scripts/route-eth0 192.168.178.0/24 via 192.168.1.1 eth0 default 192.168.178.200 dev eth0
[root@charon ~]# service network restart Shutting down interface eth0: [ OK ] Shutting down loopback interface: [ OK ] Bringing up loopback interface: [ OK ] Bringing up interface eth0: Determining if ip address 192.168.1.1 is already in use for device eth0... Error: either "to" is duplicate, or "eth0" is a garbage. Error: either "to" is duplicate, or "192.168.178.200" is a garbage. [ OK ] [root@charon ~]# route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface [root@charon ~]#
https://docs.fedoraproject.org/en-US/Fedora/13/html/Deployment_Guide/s1-netw...
"If the default gateway is already assigned from DHCP, the IP command arguments format can cause one of two errors during start-up, or when bringing up an interface from the down state using the ifup command: "RTNETLINK answers: File exists" or 'Error: either "to" is a duplicate, or "X.X.X.X" is a garbage.', where X.X.X.X is the gateway, or a different IP address. These errors can also occur if you have another route to another network using the default gateway. Both of these errors are safe to ignore."
This error is not "save to ignore" because it makes the network unreachable. Without the duplication and only the default route specified, I`m getting the same error, though only once, and still no routing.
Then from https://docs.fedoraproject.org/en-US/Fedora/13/html/Deployment_Guide/s1-netw...:
"You can also use the network/netmask directives format for route-interface files. The following is a template for the network/netmask format, with instructions following afterwards: [...]"
Let`s see ...
[root@charon ~]# cat /etc/sysconfig/network-scripts/route-eth0 ADDRESS0=192.168.178.0 NETMASK0=255.255.255.0 GATEWAY0=192.168.1.1
[root@charon ~]# service network restart Shutting down interface eth0: [ OK ] Shutting down loopback interface: [ OK ] Bringing up loopback interface: [ OK ] Bringing up interface eth0: Determining if ip address 192.168.1.1 is already in use for device eth0... [ OK ] [root@charon ~]# route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 192.168.178.0 192.168.1.1 255.255.255.0 UG 0 0 0 eth0 [root@charon ~]#
So why does the second approach work and the first one doesn`t? It looks still strange since eth0 is configured with 192.168.1.1 anyway --- but perhaps it`s ok since there are two more interfaces.
Figuring this out was even fast; it took less than an hour. Other things take hours over hours, and it goes on and on like this.
For some things, there isn`t even any documentation I could find, like how to make sure that virtual interfaces in dom0 have consistent names and that such interfaces are consistently connected to particular interfaces in particular domUs:
For firewalling and routing, I require a domU with three virtual interfaces and access to a physical one. Obviously, the names of the interfaces must remain consistent rather than change all the time. Otherwise it will be impossible to get the networking for all the guests sorted out.
Like in the above example: How do I make sure that eth0 of the guest will always be connected to a particular bridge and show up as a particular interface in dom0? It`s going to be the interface to the DMZ --- you can imagine what would happen if that interface suddenly shows up as the bridge guests in the LAN will be connected to ...