Autonomous system
AS8405 SONTHEIMER-IT
Unclassified RIPE
Summary
sdt.net AG (Sontheimer)
isp legacy
SONTHEIMER-IT, registered to PE Sontheimer Bernd, is the autonomous system of sdt.net AG of Aalen, Baden-Württemberg. The company began life in 1987 as Sontheimer Datentechnik GmbH and was among the first German ISPs to sell nationwide internet access in the mid-1990s; it became sdt.net AG in 2006 and now trades as a brand of TNG Stadtnetz AG.
What it's used for
- Regional fixed-line access in Baden-Württemberg: VDSL and fibre internet, plus telephony, for homes and businesses. Several assignments inside the space are explicitly named VoIP-Pool, matching the telephony side of the product line.
- The AS is single-homed behind TNG Stadtnetz, which is also the parent brand.
Notable
- The address inventory is not all sdt.net's own customers, and should not be geolocated as one block. Part of
217.140.64.0/19is sub-allocated under anIPXOnetname (the IP-leasing marketplace), and a/23inside it is assigned to Arm in San Jose, California. So some prefixes here front third parties on another continent. - Reverse DNS is essentially absent across the announced space, which removes the usual signal for separating subscriber pools from leased or business blocks.
- The registry name is a person, not the trading name — reading the holder field alone gives no hint that this is a long-running German ISP.
Interesting
- The
SWAandSDTcontact handles scattered through the objects are the fossil record of the Sontheimer lineage, still visible decades after the company changed its name twice.
This description is AI-generated, best-effort context — not authoritative, and provided without any guarantee of accuracy. Source, and how to suggest an edit.
Interconnection
Peering at a glance
Internet exchanges
No exchange port on file. Many exchanges publish no participant list, so this is not proof of absence.
Transit providers
1 upstream, 0 downstream and 1 adjacent networks observed; most-used upstreams first.
| AS | Network | Paths seen |
|---|---|---|
| AS6735 | TNG Stadtnetz GmbH | 430 |
Exchange presence is recorded rather than inferred: the directory collected by Packet Clearing House (https://www.pch.net/ixp/data) on 2026-10-31, licensed CC BY-NC-SA 3.0. Transit is inferred from observed BGP paths, never declared by either party.
Address space
Summary
IPv4 9 prefixes · 10.50K addresses IPv6 0 prefixes
| Country | Name | Prefixes |
|---|---|---|
| DE | Germany | 9 |
Registry
Allocation record
- Registry
- RIPE
- Handle
AS8405- Registry name
- SONTHEIMER-IT
- Registrant
- PE Sontheimer Bernd
- Abuse contact
- abuse@sontheimer.de
- Registered
- 1970-01-01
- Last changed
- 2024-11-18
- Allocation
- allocated
Routing security
RPKI and IRR
- RPKI
- 100% valid · 9 valid, 0 with no ROA
- ROAs
- 10 authorising AS8405
- ASPA
- no ASPA record
- IRR
- 78% registered · 7 of 9 announcements
- Route objects
- 9 naming AS8405
Reputation
Classification and threat
Unclassified Not in the curated lists. Most of the ~80,000 allocated ASNs are not.
Spamhaus DROP
Not on ASN-DROP The network as a whole is not listed.
No DROP prefixes None of its announced space is on the DROP prefix list.
Spamhaus DROP ("Don't Route Or Peer") lists space and networks run by, or hijacked for, spam and cybercrime operations: 447 networks and 1,845 prefixes, as published 2026-10-31. A short, high-confidence list, so a match is worth taking seriously, and absence from it says little on its own.
FBI IC3
No IC3 indicators Nothing from the FBI IC3 feed.
IC3 threat data is alpha. Absence of an indicator is not evidence of good behaviour, only of absence from this one feed.
Elsewhere