asn.dev

Autonomous system

AS40016 MESIROW

Unclassified ARIN

IPv4 addresses 512 2 prefixes
IPv6 prefixes 0 counted as prefixes, not addresses
Countries 1 mostly US
Exchanges 0 recorded by PCH
Upstreams 3 0 downstream
Flagged prefixes 0 none

Summary

Mesirow Financial

United States of America · AI-generated

business financial corporate

The AS handle MESIROW is held by Mesirow Financial Holdings, Inc.

What it's used for

  • The address space carries internal corporate infrastructure, evidenced by reverse DNS entries apps.mesirowfinancial.com and appsdr.mesirowfinancial.com and netnames MESIROW and CERF-MESIROW-A.
  • The AS announces 512 IPv4 addresses across 2 prefixes with 3 observed neighbours, indicating a small-scale internal network rather than a transit or access provider.
  • Traffic from this AS consists of office workers and internal application endpoints for a privately held financial services firm based in Chicago, Illinois.

Notable

  • Registrants align with the announcer, listing Mesirow Financial for both prefixes, with one prefix also referencing ATand T Enhanced Network Services.
  • The address inventory is compact, consisting of two /24 blocks, which is typical for a single corporate entity managing its own IP space.

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

Full topology · Graph

Internet exchanges

No exchange port on file. Many exchanges publish no participant list, so this is not proof of absence.

Transit providers

3 upstream, 0 downstream and 3 adjacent networks observed; most-used upstreams first.

ASNetworkPaths seen
AS23352DEFT.COM59
AS174Cogent Communications, LLC49
AS3356Level 3 Parent, LLC8

Exchange presence is recorded rather than inferred: the directory collected by Packet Clearing House (https://www.pch.net/ixp/data) on 2026-10-14, licensed CC BY-NC-SA 3.0. Transit is inferred from observed BGP paths, never declared by either party.

Address space

Summary

Shape and geography

IPv4 2 prefixes · 512 addresses IPv6 0 prefixes

CountryNamePrefixes
USUnited States of America2

Registry

Allocation record

ARIN · via Atlas (registry + RDAP)
Registry
ARIN
Handle
AS40016
Registry name
MESIROW
Registrant
MESIROW FINANCIAL HOLDINGS, INC.
Abuse contact
perry.rhone@mesirow.com
Registered
2006-06-07
Last changed
2026-09-25
Allocation
assigned

Routing security

RPKI and IRR

Full detail
RPKI
0% valid · 0 valid, 2 with no ROA
ROAs
0 authorising AS40016
ASPA
no ASPA record
IRR
0% registered · 0 of 2 announcements 2 other origin
Route objects
0 naming AS40016

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: 442 networks and 1,773 prefixes, as published 2026-10-13. 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

Cross-check