/etc/network/if-up.d/vzifup-post is in vzctl 4.9.4-5.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
1 2 3 4 5 | #!/bin/sh
[ "$ADDRFAM" = "inet" -o "$ADDRFAM" = "inet6" ] || exit 0
exec /usr/sbin/vzifup-post "$IFACE"
|