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Add required family flag for conntrack IPv6 operation
This change causes kube-proxy to supply the required "-f ipv6"
family flag whenever the conntrack utility is executed and the
associated service is using IPv6.
This change is required for IPv6-only operation.
Note that unit test coverage for the 2-line changes in
pkg/proxy/iptables/proxier.go and /pkg/proxy/ipvs/proxier.go will need
to be added after support for IPv6 service addresses is added to these
files. For pkg/proxy/iptables/proxier.go, this coverage will be added
either with PR #48551.
fixes#52027
**What this PR does / why we need it**:
Kube-proxy is currently not supplying the required "-f ipv6" family flag whenever it
calls the conntrack utility and the associated service is using an IPv6 service IP address.
This means that for IPv6-only operation, conntrack is not properly cleaning up
stale UDP connections, and this may be effecting ip6tables operation.
**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes # 52027
**Special notes for your reviewer**:
**Release note**:
```release-note
NONE
```
The following changes are proposed for the iptables proxier:
* There are three places where a string specifying IP:port is parsed
using something like this:
if index := strings.Index(e.endpoint, ":"); index != -1 {
This will fail for IPv6 since V6 addresses contain colons. Also,
the V6 address is expected to be surrounded by square brackets
(i.e. []:). Fix this by replacing call to Index with
call to LastIndex() and stripping out square brackets.
* The String() method for the localPort struct should put square brackets
around IPv6 addresses.
* The logging in the merge() method for proxyServiceMap should put brackets
around IPv6 addresses.
* There are several places where filterRules destination is hardcoded to
/32. This should be a /128 for IPv6 case.
* Add IPv6 unit test cases
fixes#48550
This change causes kube-proxy to supply the required "-f ipv6"
family flag whenever the conntrack utility is executed and the
associated service is using IPv6.
This change is required for IPv6-only operation.
Note that unit test coverage for the 2-line changes in
pkg/proxy/iptables/proxier.go and /pkg/proxy/ipvs/proxier.go will need
to be added after support for IPv6 service addresses is added to these
files. For pkg/proxy/iptables/proxier.go, this coverage will be added
either with PR #48551.
fixes#52027
This changes the userspace proxy so that it cleans up its conntrack
settings when a service is removed (as the iptables proxy already
does). This could theoretically cause problems when a UDP service
as deleted and recreated quickly (with the same IP address). As
long as packets from the same UDP source IP and port were going to
the same destination IP and port, the the conntrack would apply and
the packets would be sent to the old destination.
This is astronomically unlikely if you did not specify the IP address
to use in the service, and even then, only happens with an "established"
UDP connection. However, in cases where a service could be "switched"
between using the iptables proxy and the userspace proxy, this case
becomes much more frequent.
Jeff Grafton