AS343

AS343 is a legacy autonomous system number registered under ARIN to the United States Department of Defense (DoD) and operated through the Defense Information Systems Agency (DISA) — specifically DISA-Columbus and the DoD Network Information Center (DoD NIC). It is not a standalone registry record: ARIN returns the parent block DNIC-ASBLK-00306-00371, which spans AS306 through AS371 and was registered on 1989-06-30, making it one of the oldest ASN allocations on the Internet. Operationally AS343 is a single-homed stub network. It originates two legacy /16 IPv4 prefixes in the DoD-held 55.0.0.0/8 space (55.55.0.0/16 and 55.94.0.0/16, roughly 131,072 addresses) plus one IPv6 block (2608:14b:6300::/40), and its only observed BGP neighbor is AS306, also a DoD/DNIC system. The prefixes are attributed in third-party data to Headquarters, USAISC (U.S. Army Information Systems Command). RIPEstat's as-overview snapshot on 2026-06-28 reports the AS as not currently announced (announced=false, zero announced space), yet announced-prefixes shows the three prefixes routing as recently as 2026-06-26 with near-full RIS visibility (324/326 IPv4 peers, 324/324 IPv6), so the withdrawal appears very recent rather than long dormant. No RPKI ROAs cover the prefixes (bgp.he.net shows 0 valid / 0 invalid and flags bogon announcements). No notable public abuse signal was found as of 2026-06-28: AS343 is absent from the Spamhaus ASN-DROP feed and surfaces no AbuseIPDB, GreyNoise, or NANOG hits for the AS or its ranges — consistent with a closed government/military network.

Operator

United States Department of Defense (DoD), operated by DISA (Defense Information Systems Agency) / DoD Network Information Center, DISA-Columbus [Confirmed] — ARIN RDAP autnum/343 (registrant USDDD), ipinfo.io/AS343, bgp.tools/as/343

Country / RIR

US, ARIN [Confirmed] — ARIN RDAP autnum/343; RIPEstat abuse-contact-finder (authoritative_rir: arin)

Allocated

1989-06-30 (ARIN autnum top-level registration event for block DNIC-ASBLK-00306-00371, which covers AS306–AS371 including AS343); last changed 2025-09-12 [Confirmed] — ARIN RDAP autnum/343 top-level events

Org status

active U.S. federal government agency (DoD); registrant handle USDDD; org address 3990 E. Broad Street, Columbus, OH 43218; NOC/technical DISA-Columbus, 300 North James Road, Whitehall, OH 43213 [Confirmed] — ARIN RDAP autnum/343, entity/USDDD

Contacts

abuse/hostmaster disa.columbus.ns.mbx.hostmaster-dod-nic@mail.mil; registrations disa.columbus.ns.mbx.arin-registrations@mail.mil; +1-844-347-2457 ext2 [Confirmed] — ARIN RDAP autnum/343, RIPEstat abuse-contact-finder

Security/abuse context (NEUTRAL, DATED)

no notable public abuse signal found as of 2026-06-28 — absent from Spamhaus ASN-DROP (live JSON), no AbuseIPDB/GreyNoise/Emerging Threats hits, no AS343-specific NANOG thread (the 2021 anomalous-DoD-routing thread was AS8003/GRSCORP, different prefixes)

Network & routing

Network type

U.S. federal government / military network; single-homed stub AS with no transit/downstream [Confirmed] — bgp.tools/as/343, bgp.he.net/AS343, ipinfo.io/AS343

Size

2 IPv4 prefixes (55.55.0.0/16, 55.94.0.0/16; ~131,072 addresses) + 1 IPv6 prefix (2608:14b:6300::/40) [Confirmed] — RIPEstat announced-prefixes, bgp.he.net/AS343

Routing/peering

borderline-announced — RIPEstat as-overview reports announced=false and 0 announced space on 2026-06-28, but the 3 prefixes routed through 2026-06-26 with near-full visibility (324/326 v4, 324/324 v6) [Likely currently quiet] — stat.ripe.net as-overview / routing-status. First seen 2009-04-23 (55.94.0.0/16); single observed neighbor AS306 (also DoD); avg AS path length 8.158 [Confirmed]

Peering policy

none public — no PeeringDB entry, no IRR policy; single peer/upstream AS306. DoD/DISN external connectivity is governed by DoD CIO-approved gateways under DISN policy, not open commercial peering [Confirmed for absence; Likely for DISN governance] — bgp.he.net/AS343, bgp.tools/as/343, DISN CPG (dod.cyber.mil)

RPKI

no ROAs — bgp.he.net shows 0 RPKI-valid and 0 RPKI-invalid origins; prefixes are RPKI-unknown; bgp.he.net flags bogon announcements [Confirmed] — bgp.he.net/AS343

Notable usage

DoD Network Information Center — administrative/technical hub for DoD IP/ASN registration in ARIN; prefixes attributed to Headquarters, USAISC (U.S. Army Information Systems Command) [Confirmed for NIC role and prefix labels; Likely for the USAISC attribution via third-party DB] — bgp.he.net/AS343, networksdb.io

Related ASNs

AS306 (sole observed neighbor/upstream, same DoD DNIC block AS306–AS371) [Confirmed] — ARIN RDAP autnum/343, bgp.he.net/AS343

Analyst note

Encountered as a very old DoD/DNIC block-level allocation; the RDAP handle is AS306 (block-level), not a per-AS record. Stub AS, recently quiet, no RPKI, no abuse signal. Operator domain is nic.mil (not publicly browsable); parent agency disa.mil.