Hello Tinc list!
I'm trying to set up a Tinc VPN between two KVM host machines so that a
VM on one host can communicate with a VM on the other host. While I do
have a good bit of experience with virtualization, I'm not a
particularly savvy network guy, so this is proving to be a pretty big
challenge.
Requirements:
* ALL VM network traffic must be secure.
* VMs on one host must be able to communicate with VMs on other hosts.
* As I'm using another group's images for the VMs and will have no
control over the VMs once they're up and running, all configuration
needs to happen on the hosts and be invisible to the VMs.
My test setup:
* Two RHEL6.2 hosts, each running KVM with one VM set up on each host.
* Tinc set up on both hosts.
Configurations for each host:
=====
=Host1=
=====
tinc.conf:
Name = host1
ConnectTo = host2
tinc-up:
#!/bin/sh
ifconfig $INTERFACE 10.90.41.241 netmask 255.255.252.0
hosts/host1:
Address = host1.my.domain
Subnet = 10.90.41.241
Port = 655
-----BEGIN RSA PUBLIC KEY-----
keygibberrish
-----END RSA PUBLIC KEY-----
hosts/host2:
Address = host2.my.domain
Subnet = 10.90.42.242/32
Port = 655
-----BEGIN RSA PUBLIC KEY-----
keygibberrish
-----END RSA PUBLIC KEY-----
ifconfig results for VPN:
test Link encap:UNSPEC HWaddr
00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
inet addr:10.90.41.241 P-t-P:10.90.41.241 Mask:255.255.252.0
UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1
RX packets:5 errors:0 dropped:0 overruns:0 frame:0
TX packets:5 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:500
RX bytes:420 (420.0 b) TX bytes:420 (420.0 b)
=====
=Host2=
=====
tinc.conf:
Name = host1
tinc-up:
#!/bin/sh
ifconfig $INTERFACE 10.90.42.242 netmask 255.255.252.0
hosts/host1:
Address = host1.my.domain
Subnet = 10.90.41.241
Port = 655
-----BEGIN RSA PUBLIC KEY-----
keygibberish
-----END RSA PUBLIC KEY-----
hosts/host2:
Address = host2.my.domain
Subnet = 10.90.42.242/32
Port = 655
-----BEGIN RSA PUBLIC KEY-----
keygibberrish
-----END RSA PUBLIC KEY-----
ifconfig results for VPN:
test Link encap:UNSPEC HWaddr
00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
inet addr:10.90.42.242 P-t-P:10.90.42.242 Mask:255.255.252.0
UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1
RX packets:5 errors:0 dropped:0 overruns:0 frame:0
TX packets:5 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:500
RX bytes:420 (420.0 b) TX bytes:420 (420.0 b)
At this point, Tinc seems to work. Pings from host1 to 10.90.42.242 are
replied to, and pings from host2 to 10.90.41.241 are replied to.
Now to set up networking for the VMs...
My first thought was to simply bridge the VM connection to the VPN
interface. So, in virt-manager, I went into the details tab of my VM on
host1, selected the NIC, and chose "Host device test : macvtap" as the
source device and "bridge" for the source mode. Cranked up the vm and
got: "Error starting domain: error creating macvtap type of interface:
Invalid argument."
So I tried to manually create the bridge and add the "test" device to it.
[root@host1 test]# brctl addbr br0
[root@host1 test]# brctl addif br0 test
can't add test to bridge br0: Invalid argument
I did some more research on bridges, and decided that maybe I needed to
specify the deviceType and interface in tinc.conf. So I changed my
tinc.confs:
host1 tinc.conf:
Name = host1
DeviceType = tun
Interface = tun0
ConnectTo = host2
host2 tinc.conf:
Name = host2
DeviceType = tun
Interface = tun0
Restarted Tincd on both hosts and tried my pings again. They worked, so
I tried to bridge the new tun0 device.
[root@host1 test]# brctl addif br0 tun0
can't add tun0 to bridge br0: Invalid argument
No dice, again. So I tried to specify as a tap device in tinc.conf:
host1 tinc.conf:
Name = host1
DeviceType = tap
Interface = tap0
ConnectTo = host2
host2 tinc.conf:
Name = host2
DeviceType = tap
Interface = tap0
Restarted tincd and it cried about /dev/tap0 not existing. So I made it:
mknod /dev/tap0 c 36 16
Restarted tincd and tried my pings again. They went unanswered. =\ Ran a
tracepath on the IP and got:
[root@host1 test]# tracepath 10.90.42.242
1: 10.90.41.241 (10.90.41.241)
0.123ms pmtu 1500
1: 10.90.42.242 (10.90.42.242)
0.524ms pmtu 1445
1: no reply
2: no reply
3: no reply
So it looks like the ping is actually getting from host1 to host2, but
host2 doesn't realize it's there. WTH?
Just for fun I tried to bridge the tap0 interface, and it worked:
[root@host1 test]# brctl addif br0 tap0
[root@host1 test]# brctl show
bridge name bridge id STP enabled
interfaces
br0 8000.120ab67c44bd no
tap0
I found that curious, so checked the ifconfig for tap0 and noticed that
the Link encap was now defined as "Ethernet" where it was "UNSPEC"
before. I can only assume that's why I wasn't able to bridge the VPN
earlier.
tap0 Link encap:Ethernet HWaddr 12:0A:B6:7C:44:BD
inet addr:10.90.41.241 Bcast:10.90.43.255 Mask:255.255.252.0
inet6 addr: fe80::100a:b6ff:fe7c:44bd/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:17 errors:0 dropped:0 overruns:0 frame:0
TX packets:16 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:500
RX bytes:10905 (10.6 KiB) TX bytes:1224 (1.1 KiB)
So that's where I'm at now. It seems that using a tap is getting me 95%
of the way there. Google is not providing me with any more useful
suggestions, so I come to you, the members of this list, with the
following question:
Is there a way to configure Tinc to accomplish what I'm trying to do, or
do I need to try to find some other solution?
Thanks for your time,
Eric
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