[SOLVED] Switching to TUN / TAP for KVM / QEMU

fruitwerks · 09-17-2014, 03:18 PM

Hi All as the title says I am wanting to try tun / tap for my virtual machines. I have a very static config that I have used for years. Right now my box is up to date and bridged networking is getting to be a pain as far as performance.

What I have right now is the host machine that is also a firewall / router. I have about 20 devices connected and a few virtual machines, I have one subnet for everything. Two dd-wrt routers and a dual nic are working for me as far as that goes.

Lets assume I have all the kernel & utilities installed. A static IP for my LAN of 192.168.0.1 - "eth0" and a DHCP address for my internet on "eth1".

Other than the firewall script, here is what I have right now for my net config:

Code:

config_enp4s0="null"
bridge_brkvm="enp4s0"
config_brkvm="192.168.0.1/24"
brctl_brkvm="setfd 0 sethello 30 stp off"

I like to use static for always on devices, and wifi / on demand stuff is handled by one of three DHCP servers - yes three, and one subnet, something broke a while back and this was my fix.

Now I need everything to be able to talk to each other, and I am open to using another subnet given the above, if that makes things easier.

Unfortunately all I am finding are conflicting docs and stuff from like 2004, or recent stuff that doesn't cover my situation. I need to be able to reach any device from any device and all traffic needs to eventually use 192.168.0.1 as the gateway. All help / suggestions are welcome.

Thanks

fruitwerks · 09-19-2014, 11:49 PM

Anyway.. This was solved.. please reply if you were curious - If not I will update this in a few days with my solution.

fruitwerks · 09-21-2014, 08:16 PM

Since this post I have moved the firewall role off of this machine. Although before I did that I changed to tun tap. Ping times lowered, but overall performance (network) did not improve.

End Result:

Code:

config_enp4s0="null"
config_tap0="null"
modules_tap0="!dhclient !dhcpcd !ifconfig iproute2 !pump !udhcpc !wireless"
tuntap_tap0="tap"

bridge_br0="enp4s0 tap0"
modules_br0="!dhclient !dhcpcd !ifconfig iproute2 !pump !udhcpc !wireless"
rc_net_br0_need="net.tap0 net.enp4s0"
config_br0="192.168.0.2/24"
routes_br0="default via 192.168.0.1"

I now get transfers of ~100mb read / write - and the disk can do much more than that so more testing is required, as this is literally a 100x improvement I am happy for now.