Autonomous system detail  ·  US flag US

AS25

Announced

Operated by University of California at Berkeley, US flag US.

Summary

// analyst note
A clean, long-established academic allocation; encountering it indicates UC Berkeley campus space. Routine higher-ed network.
// security note
NEUTRAL/DATED: no notable public abuse signal found as of 2026-06-07; routine higher-ed network (abuse@security.berkeley.edu).
IPv4 prefixes
13
~206.1K addresses
IPv6 prefixes
2
announced
Peer networks
1
1 up · 0 down
IANA block
1-1876
Assigned by ARIN
[ 01 ] — Context

About this ASN.

Updated  ·  Confidence: High  ·  4 sources  ·  How this page is checked

AS25 is the University of California, Berkeley's campus network ASN, an original 1984 allocation registered under ARIN to UC Berkeley's IST–Telecommunications. Berkeley holds a central place in early Internet history as the home of BSD Unix, which carried the reference TCP/IP implementation that propagated across the early Internet, making this a number with genuine heritage behind a routine modern campus network. As of June 2026 it originates about a dozen IPv4 prefixes and two IPv6 prefixes (~202,000 IPv4 addresses), and it is effectively single-homed via CENIC/CalREN (AS2152/AS2153), California's research-and-education backbone. For triage this is a clean, long-established academic allocation: encountering it indicates UC Berkeley campus space, with abuse handled through the university's security team. No notable public abuse signal was found as of June 2026.

Operator
University of California at Berkeley (ARIN OrgId UCAB-1-Z; IST–Telecommunications, Berkeley, CA) [Confirmed] — ARIN RDAP
Country / RIR
US, ARIN [Confirmed]
Allocated
ASN RegDate 1984-08-03; updated 2023-12-14 [Confirmed] — ARIN
Org status
active (UC Berkeley)

Security/abuse context (NEUTRAL, DATED)

no notable public abuse signal found as of 2026-06-07; routine higher-ed network (abuse@security.berkeley.edu) — ipgeolocation.io

Network & routing

Network type
research / education [Confirmed]
Size
~12 IPv4 prefixes, 2 IPv6 (~201,984 IPv4 addrs) — bgp.he.net / bgp.tools (2026-06)
Routing/peering
upstreams CENIC/CalREN (AS2152, AS2153) [Confirmed]; ~1 observed peer (effectively single-homed via CENIC); RPKI partial/Unknown
Notable usage
UC Berkeley campus network ASN; original 1984 allocation; Berkeley = home of BSD Unix (reference TCP/IP stack of the early Internet) — berkeley.edu
Related ASNs
AS393282 (UCB-1, also UC Berkeley) [Confirmed]; LBL/AS16 (Lawrence Berkeley) is a separate UC entity [historical]
Analyst note
A clean, long-established academic allocation; encountering it indicates UC Berkeley campus space. Routine higher-ed network.
[ 02 ] — Announced prefixes

What this network routes.

15 prefixes total · as observed by RouteViews at 2026-09-20 · one collector view, not a global census
// IPv4 prefixes13
  1. 128.32.0.0/16/16
  2. 136.152.0.0/16/16
  3. 169.229.0.0/16/16
  4. 169.229.176.0/20/20
  5. 169.236.240.0/21/21
  6. 208.68.240.0/22/22
  7. 192.150.186.0/23/23
  8. 192.154.4.0/23/23
  9. 192.12.234.0/24/24
  10. 192.154.6.0/24/24
  11. 192.35.209.0/24/24
  12. 209.129.246.0/24/24
  13. 67.21.36.0/24/24
// IPv6 prefixes2
  1. 2607:f140::/32/32
  2. 2607:f140:e000::/48/48
[ 03 ] — Notable peers & upstreams

Who it talks to.

1 observed neighbour
// Notable connections1 of 1 observed

Neighbours observed by RouteViews at 2026-09-20, lowest ASN first. Relationships are inferences from the CAIDA AS Relationships Dataset, 2026-08-01, and establish no commercial arrangement; a dash means the inference did not resolve.

ASNOperatorRole
AS2152 — upstream
Neighbours observed via public BGP collectors; not a complete peering list.