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From "Sean Lair (JIRA)" <j...@apache.org>
Subject [jira] [Closed] (CLOUDSTACK-10379) Using Source NAT option on Private Gateway does not work
Date Wed, 30 May 2018 13:23:00 GMT

     [ https://issues.apache.org/jira/browse/CLOUDSTACK-10379?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Sean Lair closed CLOUDSTACK-10379.
----------------------------------
    Resolution: Duplicate

Moved to:

https://github.com/apache/cloudstack/issues/2680

 

> Using Source NAT option on Private Gateway does not work
> --------------------------------------------------------
>
>                 Key: CLOUDSTACK-10379
>                 URL: https://issues.apache.org/jira/browse/CLOUDSTACK-10379
>             Project: CloudStack
>          Issue Type: Improvement
>      Security Level: Public(Anyone can view this level - this is the default.) 
>          Components: VPC
>    Affects Versions: 4.9.0, 4.10.0.0
>         Environment: KVM
>            Reporter: Sean Lair
>            Priority: Minor
>              Labels: patch
>   Original Estimate: 24h
>  Remaining Estimate: 24h
>
> There is a bug in the Private Gateway functionality, when Source NAT is enabled for
the Private Gateway.  When the SNAT is added to iptables, it has the source CIDR of the private
gateway subnet.  Since no VMs live in that private gateway subnet, the SNAT doesn’t work. 
Below is an example:
>  
>  * VMs have IP addresses in the 10.0.0.0/24 subnet.
>  * The Private Gateway address is 10.101.141.2/30
>  
> See the outputs below, see how the SOURCE field for the new SNAT (eth3) only matches
if the source is 10.101.141.0/30?  Since the VM has an IP address in 10.0.0.0/24, the VMs
don’t get SNAT’d as they should when talking across the private gateway.  The SOURCE
should be set to ANYWHERE.
>  
> BEFORE ADDING PRIVATE GATEWAY
> -----------------------------------------------
> {code:java}
> Chain POSTROUTING (policy ACCEPT 1 packets, 52 bytes)
> pkts bytes target     prot opt in     out     source              
destination
>     2   736 SNAT       all  --  any    eth2    10.0.0.0/24         
anywhere             to:10.0.0.1
>    16  1039 SNAT       all  --  any    eth1    anywhere            
anywhere             to:46.99.52.18{code}
>  
> AFTER ADDING PRIVATE GATEWAY W/ SNAT
> -----------------------------------------------
> {code:java}
> Chain POSTROUTING (policy ACCEPT 0 packets, 0 bytes)
> pkts bytes target     prot opt in     out     source              
destination
>     0     0 SNAT       all  --  any    eth3    10.101.141.0/30     
anywhere             to:10.101.141.2
>     2   736 SNAT       all  --  any    eth2    10.0.0.0/24         
anywhere             to:10.0.0.1
>    23  1515 SNAT       all  --  any    eth1    anywhere            
anywhere             to:46.99.52.18
> {code}
>  
>  It looks like CsAddress.py treats the creation of the Private Gateway SNAT as if it
is a GUEST network, which works fine, except for the SNAT problem shown above.  Here is the
code from MASTER (line 479 is SNAT rule):
>   
> {code:java}
> if self.get_type() in ["guest"]:
> ...
> ...
>     self.fw.append(["nat", "front",
>         "-A POSTROUTING -s %s -o %s -j SNAT --to-source %s" %
>         (guestNetworkCidr, self.dev, self.address['public_ip'])])
> {code}
>  
> I am thinking we just change that to the following.  I can’t think of any reason we
need the source/guest CIDR specified:
>  
> {code:java}
> if self.get_type() in ["guest"]:
> ...
> ...
>     self.fw.append(["nat", "front",
>         "-A POSTROUTING -o %s -j SNAT --to-source %s" %
>         (self.dev, self.address['public_ip'])])
> {code}
>  
> THE NAT TABLE IF THE ABOVE CODE CHANGE IS MADE
> -----------------------------------------------
> {code:java}
> Chain POSTROUTING (policy ACCEPT 0 packets, 0 bytes)
> pkts bytes target     prot opt in     out     source              
destination
>     0     0 SNAT       all  --  any    eth3    anywhere            
anywhere             to:10.101.141.2
>     2   736 SNAT       all  --  any    eth2    anywhere            
anywhere             to:10.0.0.1
>    23  1515 SNAT       all  --  any    eth1    anywhere            
anywhere             to:46.99.52.18
> {code}
>  



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