[jira] [Created] (CLOUDSTACK-9143) Setup routes for RFC 1918 ip space

["Remi Bergsma (JIRA)" <ji...@apache.org>]

Remi Bergsma created CLOUDSTACK-9143:
----------------------------------------

             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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