IP4_ADDR_1
SYS(fail, "ip -n %s a add %s/24 dev veth1", ns1, IP4_ADDR_1);
SYS(fail, "ip route add %s/32 dev veth2 %s", IP4_ADDR_1, vrf);
#define IP4_ADDR_SRC IP4_ADDR_1
SYS(fail, "ip route add %s/32 dev veth4 via %s", IP4_ADDR_1, IP4_ADDR_3);
IP4_ADDR_1, IP4_ADDR_GRE);