see
linux commit
321827477360934dc040e9d3c626bf1de6c3ab3c
icmp: don't send out ICMP messages with a source address of 0.0.0.0
"RFC7600 reserves a dummy address to be used as a source for ICMP
messages (192.0.0.8/32), so let's teach the kernel to substitute that
address as a last resort if the regular source address selection procedure
fails."
#define INADDR_BROADCAST ((in_addr_t) 0xffffffff)
#define INADDR_NONE ((in_addr_t) 0xffffffff)
#define INADDR_LOOPBACK ((in_addr_t) 0x7f000001)
+#define INADDR_DUMMY ((in_addr_t) 0xc0000008)
#define INADDR_UNSPEC_GROUP ((in_addr_t) 0xe0000000)
#define INADDR_ALLHOSTS_GROUP ((in_addr_t) 0xe0000001)