Remi Bergsma created CLOUDSTACK-9143:
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Summary: Setup routes for RFC 1918 ip space
Key: CLOUDSTACK-9143
URL: https://issues.apache.org/jira/browse/CLOUDSTACK-9143
Project: CloudStack
Issue Type: Bug
Security Level: Public (Anyone can view this level - this is the default.)
Components: Virtual Router
Reporter: Remi Bergsma
Assignee: Remi Bergsma
Priority: Critical
Fix For: 4.7.0
Setup general route for RFC 1918 space, as otherwise it will be sent to the
public gateway and likely to be dropped (internet providers do not route ip
space that is meant for internal use). More specific routes that may be set
have preference over this generic routes so this works even with private ranges
used for public ip space (as shown below).
When using an internal DNS server some hosts may resolve to an RFC 1918 ip
address. The SSVM has a default gw to public so if it has no route for this ip
address space, it will not work. This PR makes generic RFC 1918 (so all
internal ip adresses like 10.0.0.10 etc) to the local management gateway. This
makes them reachable. Without this fix, it is sent upstream and it is dropped
there.
Should there be a more generic route (smaller prefix), this has preference over
the generic routes.
Example in my dev environment:
```
root@v-1-VM:~# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 192.168.23.1 0.0.0.0 UG 0 0 0 eth2
10.0.0.0 192.168.22.1 255.0.0.0 UG 0 0 0 eth1
169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth0
172.16.0.0 192.168.22.1 255.240.0.0 UG 0 0 0 eth1
192.168.0.0 192.168.22.1 255.255.0.0 UG 0 0 0 eth1
192.168.22.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1
192.168.23.0 0.0.0.0 255.255.255.0 U 0 0 0 eth2
```
Route `192.168.0.0/16` goes via `eth1` but `192.168.23.0/24` is more specific
and has preference and goes via `eth2`. It works:
```
root@v-1-VM:~# ping 8.8.8.8
PING 8.8.8.8 (8.8.8.8): 48 data bytes
56 bytes from 8.8.8.8: icmp_seq=0 ttl=49 time=7.179 ms
^C--- 8.8.8.8 ping statistics ---
1 packets transmitted, 1 packets received, 0% packet loss
round-trip min/avg/max/stddev = 7.179/7.179/7.179/0.000 ms
```
This solves a lot of the 'internal resolving' issues we face.
When the public ip address is RFC1918 itself, we do not set the routes.
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