Autonomous system detail

AS25

Announced

Operated by UCB - University of California at Berkeley.

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
12
~205.8K 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

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.

14 prefixes total · RIPEstat data · cached, not real-time
// IPv4 prefixes12
  1. 136.152.0.0/16/16
  2. 128.32.0.0/16/16
  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. 192.154.6.0/24/24
  10. 192.12.234.0/24/24
  11. 67.21.36.0/24/24
  12. 192.35.209.0/24/24
// 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 connectionsTop 1 of 1
ASNOperatorRole
AS2152 CENIC-2152 - CENIC upstream
Neighbours observed via public BGP collectors; not a complete peering list.