TEST_IPV4
SYS(out, "ip -4 addr add %s dev lo", TEST_IPV4);
SYS_NOFAIL("ip -4 addr del %s dev lo", TEST_IPV4);
SYS_NOFAIL("ip -4 addr del %s dev lo", TEST_IPV4);
SYS(fail, "ip -4 addr add %s/8 dev %s1", TEST_IPV4, TEST_IF_PREFIX);
#define SRC4_REWRITE_IP TEST_IPV4