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Aloha. Opening and closing VPN tunnels results in as many utun interfaces as the amount of times the tunnel has been opened. These interfaces stay present and seem to be removed only upon system reboot. We are using the NetworkExtension as a SystemExtension on macOS to create the virtual interfaces. Is this the normal behaviour. Has anybody else experienced this? utun0: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1380 inet6 fe80::8038:c353:17cd:c422%utun0 prefixlen 64 scopeid 0xf nd6 options=201<PERFORMNUD,DAD> utun1: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 2000 inet6 fe80::cfb6:1324:d7e9:5d5%utun1 prefixlen 64 scopeid 0x10 nd6 options=201<PERFORMNUD,DAD> utun2: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1300 options=6463<RXCSUM,TXCSUM,TSO4,TSO6,CHANNEL_IO,PARTIAL_CSUM,ZEROINVERT_CSUM> utun3: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1300 options=6463<RXCSUM,TXCSUM,TSO4,TSO6,CHANNEL_IO,PARTIAL_CSUM,ZEROINVERT_CSUM> utun4: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1300 options=6463<RXCSUM,TXCSUM,TSO4,TSO6,CHANNEL_IO,PARTIAL_CSUM,ZEROINVERT_CSUM> utun5: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1300 options=6463<RXCSUM,TXCSUM,TSO4,TSO6,CHANNEL_IO,PARTIAL_CSUM,ZEROINVERT_CSUM> utun6: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1300 options=6463<RXCSUM,TXCSUM,TSO4,TSO6,CHANNEL_IO,PARTIAL_CSUM,ZEROINVERT_CSUM> utun7: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1300 options=6463<RXCSUM,TXCSUM,TSO4,TSO6,CHANNEL_IO,PARTIAL_CSUM,ZEROINVERT_CSUM> utun8: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1300 options=6463<RXCSUM,TXCSUM,TSO4,TSO6,CHANNEL_IO,PARTIAL_CSUM,ZEROINVERT_CSUM>

It seems that IPv4 UDP packets that have no checksum set (i.e. checksum = 0x0000) are filtered out and cannot be received via an UDP socket that is listening even though they are valid UDP packets (according to RFC768).We are trying to receive IPSec ESP packets that are UDP encapsulated. In this case RFC3948 prescribes that "the IPv4 UDP Checksum SHOULD be transmitted as a zero value".We are using POSIX sockets (not raw sockets) and are using the NetworkExtension and or developing for macOS.We have triedsudo sysctl net.inet.udp.checksum=0to switch-off the checksum checking, but this didn't seem to make any difference.Is there a way to receive these packets? Preferrably without needing admin rights.Thanks