VETH1_ADDR6
err = make_sockaddr(AF_INET6, VETH1_ADDR6, 0, &saddr, &saddr_len);
SYS(fail, "ip -6 -net " NS1 " addr add " VETH1_ADDR6 "/64 dev " VETH1 " nodad");
up = !SYS_NOFAIL("ip netns exec " NS0 " ping -6 -c 1 -W 1 " VETH1_ADDR6);