Support nonMasqueradeCIDRs

[anfernee]

Describe the problem/challenge you have
When a pod talks to an external address, ip-masq-agent controls a list of CIDR ranges no to masquerade by nonMasqueradeCIDRs. It's useful to some cloud providers that controls some internal addresses that are flat to the podCIDR. Antrea provides an option noSNAT, but it applies to all destination addresses.

Describe the solution you'd like
Support ip-masq-agent on windows and linux, or provide an option for nonMasqueradeCIDRs on antrea-agent.

[antoninbas]

Support ip-masq-agent on windows and linux

On Linux:
I believe that when using noEncap mode, you should be able to set noSNAT in the Antrea configuration, while deploying ip-masq-agent alongside Antrea with the desired value for nonMasqueradCIDRs

On Windows:
AFAIK, ip-masq-agent does not work on Windows Nodes. The Antrea noSNAT configuration is ignored on Windows, since we do not support noEncap mode on Windows. This feature request seems to only apply in noEncap mode, so it seems that this issue is dependent on that one: #1632

If you're looking for a unified solution across Linux and Windows, looks like we will need to implement something like nonMasqueradeCIDRs in Antrea directly, once we figure out noEncap & noSNAT on Windows Nodes.

[jianjuns]

Agreed this is can be a good feature. Probably we can extend the noSNAT option for supporting a noSNAT feature.

On Windows, I remember @ruicao93 has a draft PR already, so hopefully we will get it soon.

[github-actions]

This issue is stale because it has been open 180 days with no activity. Remove stale label or comment, or this will be closed in 180 days

[github-actions]

This issue is stale because it has been open 90 days with no activity. Remove stale label or comment, or this will be closed in 90 days