[Release 1.25] Update Flannel to fix NAT issue with older iptables version

[rbrtbnfgl]

Backport for #7096

[VestigeJ]

Reproduced using VERSION=v1.25.7+k3s1

CENTOS 7.9 Reproduction

bare node installation no configs
$ sudo INSTALL_K3S_VERSION=v1.25.7+k3s1 INSTALL_K3S_EXEC=server ./install-k3s.sh

$ sudo iptables -t nat -vnL | grep -i flannel

Chain FLANNEL-POSTRTG (0 references)

$ iptables --version

iptables v1.4.21

$ k3s -v

k3s version v1.25.7+k3s1 (f7c20e23)
go version go1.19.6

$ grep /etc/os-release -i -e pretty

PRETTY_NAME="CentOS Linux 7 (Core)"

CENTOS 7.9 Validation

upgrade existing single node installation from v1.25.7+k3s1 -> v1.25.8-rc2+k3s1
$ sudo INSTALL_K3S_VERSION=v1.25.8-rc2+k3s1 INSTALL_K3S_EXEC=server ./install-k3s.sh

$ k3s -v

k3s version v1.25.8-rc2+k3s1 (6c5ac022)
go version go1.19.7

$ iptables --version

iptables v1.4.21

$ sudo iptables -t nat -vnL | grep -i flannel

  149  8989 FLANNEL-POSTRTG  all  --  *      *       0.0.0.0/0            0.0.0.0/0            /* flanneld masq */
Chain FLANNEL-POSTRTG (1 references)
    0     0 RETURN     all  --  *      *       0.0.0.0/0            0.0.0.0/0            mark match 0x4000/0x4000 /* flanneld masq */
  115  6900 RETURN     all  --  *      *       10.42.0.0/24         10.42.0.0/16         /* flanneld masq */
    0     0 RETURN     all  --  *      *       10.42.0.0/16         10.42.0.0/24         /* flanneld masq */
    0     0 RETURN     all  --  *      *      !10.42.0.0/16         10.42.0.0/24         /* flanneld masq */
    1    45 MASQUERADE  all  --  *      *       10.42.0.0/16        !224.0.0.0/4          /* flanneld masq */
    0     0 MASQUERADE  all  --  *      *      !10.42.0.0/16         10.42.0.0/16         /* flanneld masq */

Ubuntu 18.04 Reproduction

bare node installation no configs
$ sudo INSTALL_K3S_VERSION=v1.25.7+k3s1 INSTALL_K3S_EXEC=server ./install-k3s.sh

$ sudo iptables -t nat -vnL | grep -i flannel

Chain FLANNEL-POSTRTG (0 references)

$ iptables --version

iptables v1.6.1

$ k3s -v

k3s version v1.25.7+k3s1 (f7c20e23)
go version go1.19.6

$ grep /etc/os-release -i -e pretty

PRETTY_NAME="Ubuntu 18.04.6 LTS"

Ubuntu 18.04 Validation

upgrade existing single node installation

$ sudo INSTALL_K3S_VERSION=v1.25.8-rc2+k3s1 INSTALL_K3S_EXEC=server ./install-k3s.sh

$ k3s -v

k3s version v1.25.8-rc2+k3s1 (6c5ac022)
go version go1.19.7

$ iptables --version

iptables v1.6.1

$ sudo iptables -t nat -vnL | grep -i flannel

   52  3144 FLANNEL-POSTRTG  all  --  *      *       0.0.0.0/0            0.0.0.0/0            /* flanneld masq */
Chain FLANNEL-POSTRTG (1 references)
    0     0 RETURN     all  --  *      *       0.0.0.0/0            0.0.0.0/0            mark match 0x4000/0x4000 /* flanneld masq */
   40  2400 RETURN     all  --  *      *       10.42.0.0/24         10.42.0.0/16         /* flanneld masq */
    0     0 RETURN     all  --  *      *       10.42.0.0/16         10.42.0.0/24         /* flanneld masq */
    0     0 RETURN     all  --  *      *      !10.42.0.0/16         10.42.0.0/24         /* flanneld masq */
    1    45 MASQUERADE  all  --  *      *       10.42.0.0/16        !224.0.0.0/4          /* flanneld masq */
    0     0 MASQUERADE  all  --  *      *      !10.42.0.0/16         10.42.0.0/16         /* flanneld masq */