[CLOUDSTACK-8451] Static Nat show wrong remote IP in VM behind VPC

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 4.4.3, 4.3.2, 4.5.1
• Component/s: KVM, Network Controller, Virtual Router
• Security Level: Public (Anyone can view this level - this is the default.)
• Environment: Ubuntu 14.04, ACS 4.5.1-SNAPSHOT
• Assignee: Unassigned
• Reporter: Andrija Panic
• Created: 07/May/15 13:04
• Updated: 09/Mar/17 10:14

Description

When configuring Port FOrwarding or Static NAT on VPC VR, and connect from outside world to VPC IP address, traffic gets forwarded to VM behind VPC.

But if you run "netstat -antup | grep $PORT" (where port is i.e. ssh port) - given result will show that remote connections come from the Source NAT IP of the VR, instead of the real remote client IP.

Example:
private VM: 192.168.10.10
Source NAT IP on VPC VR: 1.1.1.1
Additional Public IP on VPC VR. 1.1.1.2
Remote client public IP: 4.4.4.4 (external to VPC)
Test:
from 4.4.4.4 SSH to 1.1.1.2 port 22 (or any other port)
inside 192.168.10.10 do "netstat -antup | grep 22"
Result: Remote IP show is 1.1.1.1 instead of 4.4.4.4

We found a solution (somwhat tested, and not sure if this would break anything...)

Problem is in VRs iptables NAT table, POSTROUTING chain, rule:
SNAT all – * eth2 0.0.0.0/0 0.0.0.0/0 to:1.1.1.1

where 1.1.1.1 is public IP of VR
eth2: is Public Interface of VR
When this rule is deleted, NAT is working fine.

This is serious issue for anyone using VPC, since there is no way to see real remote client IP, and this no firewall funtionality inside VM, SIP doesnt work, web server logs are useless etc.

I also experienced this problem with 4.3.x releases.

EDIT: this happens when using vlan://untagged for Public network - eth2 device gets passed to VR, and offending iptables rule is created.

When using tagged vlan for Public network - everything is fine.