qemu: Enable guest access to the internet
I would like to configure my host to allow the yocto-built qemu guest access the internet. I'm running qemu with kvm virtualization and slirp, and according to  it should just work. I'd like to find out why it doesn't.
Here's the current situation:
* The guest has ip 10.0.2.15 and can ping my host with `ping 10.0.2.2`.
* The host has no ip 10.0.0.0/16.
* The guest cannot ping my hosts only ipv4 interface (besides lo) `ping 192.168.178.24`.
* The guest cannot ping devices in the same LAN as my host: `ping 192.168.178.101`.
* The host has sysctl configured like so:
net.ipv4.conf.all.accept_source_route = 1
net.ipv4.conf.all.send_redirects = 1
net.ipv4.ip_forward = 1
net.ipv6.conf.all.accept_source_route = 1
net.ipv6.conf.all.forwarding = 1
* The hosts routing table:
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 192.168.178.1 0.0.0.0 UG 600 0 0 wlp3s0
169.254.0.0 0.0.0.0 255.255.0.0 U 1000 0 0 wlp3s0
192.168.178.0 0.0.0.0 255.255.255.0 U 600 0 0 wlp3s0
* runqemu starts qemu with hostfwd=tcp::2222-:22. That is, qemu is instructed to on the host listen on port 2222 and forward packets to port 22 of the guest.
* From the host I can ssh into the guest with `ssh root@localhost -p2222`.
When the ssh connection is up, `netstat -tupen` on the host prints
Proto Recv-Q Send-Q Local Address Foreign Address State User Inode PID/Program name
tcp 0 0 127.0.0.1:2222 127.0.0.1:37548 ESTABLISHED 1000 34788 2301/qemu-system-x8
tcp 0 0 127.0.0.1:37548 127.0.0.1:2222 ESTABLISHED 1000 40091 2331/ssh
`netstat -tuen` inside the guest prints
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 ::ffff:10.0.2.15:22 ::ffff:10.0.2.2:37548 ESTABLISHED
Has anyone any ideas?