AS10615 PAINEWEBBER-ASN

PAINEWEBBER-ASN is now held by UBS AG. PaineWebber was the American brokerage that UBS bought in 2000 and folded into its wealth-management business; the brand is long gone from the market but survives here as the ASN's handle. The reverse DNS is unambiguous about who runs it today: sampled addresses resolve to cgbf-sh90-5005a.ubs.com and ibol18-bs.ibb.ubs.com.

What it's used for

RIS observes 60 IPv4 prefixes carrying 10,240 addresses, no IPv6, and 6 observed BGP neighbours. Sixty prefixes over ten thousand addresses averages out to about a /23 apiece, and the sample confirms it: 151.191.184.0/23, 161.239.224.0/23, 148.112.144.0/23, and dozens more of exactly that size.

That uniform /23 grid is the fingerprint of a bank's site network. Each office, branch, trading floor or data hall gets a fixed-size block from one of a few parent ranges, and the sites are announced individually so traffic to each can be steered across the handful of carriers the firm buys from. Six peers, ten thousand addresses, no customers: an enterprise, closed and multi-homed, not a provider.

Notable

The prefixes come from several distinct legacy ranges — 148.112, 151.191, 161.15, 161.239, 162.65 — which is what happens when a bank absorbs another bank. Address space is the last thing to be renumbered after a merger, and often it never is; a quarter-century after the acquisition, PaineWebber's blocks are still carrying UBS traffic under PaineWebber's ASN.