Fixestailscale/tailscale#10393Fixestailscale/corp#15412Fixestailscale/corp#19808
On Apple platforms, exit nodes and subnet routers have been unable to relay pings from Tailscale devices to non-Tailscale devices due to sandbox restrictions imposed on our network extensions by Apple. The sandbox prevented the code in netstack.go from spawning the `ping` process which we were using.
Replace that exec call with logic to send an ICMP echo request directly, which appears to work in userspace, and not trigger a sandbox violation in the syslog.
Signed-off-by: Andrea Gottardo <andrea@gottardo.me>
