AS131

AS131 is a low-numbered, ARIN-registered Autonomous System held by the University of California, Santa Barbara, where it carries the registry name UCSB-NET-AS. The ARIN record shows an ASN registration event of 1987-09-30 and a most-recent change on 2024-04-26; the 1987 value is the date on the ARIN database object, not an IEEE assignment date (IEEE publishes no such dates for ASNs). In routing terms AS131 is a campus "eyeball" / stub network rather than a transit provider: it carries no customer cone and reaches the wider Internet exclusively through CENIC, the California research-and-education backbone, peering only with the CENIC ASNs AS2152 and AS2153. It originates a stable footprint of five IPv4 prefixes — 128.111.0.0/16, 169.231.0.0/16, 192.150.216.0/23, 192.35.222.0/24, 199.120.153.0/24 — totalling roughly 132,096 addresses, plus the single IPv6 block 2607:f378::/32. One operational nuance is worth flagging for anyone triaging traffic: UCSB's SecLab runs disclosed, benign Internet-wide security scans from AS131 space and publishes an opt-out notice, so AS131 addresses can appear in scan/noise feeds without indicating abuse. No DROP/ASN-DROP listing, spam-blocklist entry, or BGP-hijack incident was found as of 2026-06-12; abuse is handled at security@ucsb.edu.

Operator

University of California, Santa Barbara — UCSB-NET-AS (legal holder: The Regents of the University of California; ARIN OrgId UCSB-Z) [Confirmed] — ARIN RDAP/WHOIS (https://rdap.arin.net/registry/autnum/131)

Country / RIR

US (California), ARIN [Confirmed] — https://rdap.arin.net/registry/autnum/131

Allocated

ARIN ASN registration event 1987-09-30 (ARIN database record date, NOT an IEEE assignment date); ASN last changed 2024-04-26 [Confirmed] — https://rdap.arin.net/registry/autnum/131

Org status

active holder — public research university, part of the University of California system, governed by The Regents [Confirmed] — https://www.ucsb.edu/about

Abuse / NOC

abuse security@ucsb.edu (UCSB SOC, +1-805-893-5080); NOC noc@ucsb.edu, network ops via UCSB Office of Information Technology

Security/abuse context (NEUTRAL, DATED)

no DROP/ASN-DROP, spam-blocklist, or BGP-hijack signal found as of 2026-06-12; only elevated signal is operator-disclosed research scanning (benign). Campus incidents (2021 Accellion via UCOP; Mar-2021 phishing) were not AS131 network-layer abuse [Confirmed for absence as searched; tag Likely on null findings] — https://bgp.tools/as/131, https://it.ucsb.edu/news/ucop-security-incident-news-faqs-and-resources

Network & routing

Network type

education / campus "eyeball" / stub AS; no transit function, no customer cone [Confirmed] — https://bgp.tools/as/131

Size

5 IPv4 prefixes (128.111.0.0/16, 169.231.0.0/16, 192.150.216.0/23, 192.35.222.0/24, 199.120.153.0/24; ~132,096 addrs) + 1 IPv6 (2607:f378::/32) [Confirmed] — RIPEstat announced-prefixes (https://stat.ripe.net/data/announced-prefixes/data.json?resource=AS131), bgp.he.net/AS131

Upstreams / peering

upstream via CENIC — AS2152 (IPv4+IPv6) and AS2153 (IPv4); only BGP peers observed [Confirmed] — https://bgp.he.net/AS131, https://bgp.tools/as/131

Peering policy

no public peering policy and no PeeringDB entry; external connectivity delegated to CENIC (typical campus posture) [Likely] — https://www.peeringdb.com/, https://bgp.tools/as/131

RPKI posture

no ROAs observed (0 valid / 0 invalid) as of 2026-06-12; bgp.he.net flags an "announces bogons" anomaly (prefix unspecified) [Likely] — https://bgp.he.net/AS131

AS rank / customer-cone rank

Unknown — no numeric AS-rank or CAIDA rank returned by sources [Unknown]

Routing status

announced/active (RIPEstat announced=true) as of 2026-06-12 [Confirmed] — https://stat.ripe.net/data/as-overview/data.json?resource=131

Notable usage

campus network for a major public research university (academic, research, ResNet residential, administrative traffic). UCSB SecLab runs disclosed benign Internet-wide scans from AS131 space — IPs may show in scan feeds without being malicious

[Confirmed] — https://abuse.seclab.cs.ucsb.edu/, https://seclab.cs.ucsb.edu/

Related ASNs

AS2152 (CENIC/CalREN upstream), AS2153 (CENIC) [Confirmed] — https://bgp.he.net/AS131

AS-SETs

as-ucnet, as-calren2 [Likely] — https://bgp.tools/as/131

Analyst note

clean, long-established academic stub ASN; sole upstream CENIC; expect SecLab scan traffic from its ranges. AS rank/cone Unknown.