Salts are generally stored with the hash, and are only really intended to prevent "rainbow table" attacks. (I.e. use of precomputed hash tables.) Though a predictable and matching salt per entry does mean you can attack all the hashes for a timestamp per hash attempt.
That being said, the previous responder's point still stands that you can brute force the salted IPs at about a second per IP with the colocated salt. Using multiple hash iterations (e.g. 1000x; i.e. "stretching") is how you'd meaningfully increase computational complexity, but still not in a way that makes use of the general "can't be practically reversed" hash guarantees.
That being said, the previous responder's point still stands that you can brute force the salted IPs at about a second per IP with the colocated salt. Using multiple hash iterations (e.g. 1000x; i.e. "stretching") is how you'd meaningfully increase computational complexity, but still not in a way that makes use of the general "can't be practically reversed" hash guarantees.