AS13172 — ESO

AS13172 announces 5 IPv4 prefixes covering 1,536 addresses and 1 IPv6 prefixes.

About this network

Every address in a block answers to the same name: the last octet is left out entirely.

What it's used for

• The network of Bulgaria's electricity transmission system operator. 1,536 addresses across five IPv4 prefixes, one IPv6 prefix, and 30 observed BGP neighbours.

Notable

• Three sampled addresses in 91.211.232.0/24 all returned 91-211-232-host.eso.bg, and the same held in two further blocks.
• Netnames are ESO-EAD on two blocks and InetServices on two others.
• The blocks named InetServices list only an abuse contact.
• Nine of fifteen sampled addresses returned a name; 30 observed BGP neighbours.

Interesting

• The reverse name is built from three octets, so all 256 addresses in the block share one name. Truncating the last octet turns a per-address identifier into a per-block one, and anything that logs or filters by hostname loses the ability to tell one machine from another. Other networks in this range truncate to two octets or reverse the order; this is the furthest the idea goes.
• -host as a suffix adds nothing a reader can use, which is what remains once the varying part is gone.
• 30 neighbours for 1,536 addresses is a peering profile, not an access one. A power grid operator needs paths to many counterparties and almost no address space to do it with.

This description is AI-generated, best-effort context — not authoritative, and provided without any guarantee of accuracy.

Announced prefixes

• 91.211.232.0/24
• 91.211.234.0/23
• 185.108.188.0/24
• 185.108.191.0/24
• 195.225.127.0/24
• 2a03:d180::/32

Upstream networks

• AS3356 Level 3 Parent, LLC
• AS202 Level 3 Parent, LLC
• AS6939 Hurricane Electric LLC
• AS8262 Evolink EAD
• AS24482 SG.GS
• AS8280 SYNAPSECOM S.A. Provider of Telecommunications and Internet Services
• AS8218 Zayo Infrastructure France SA
• AS208972 GIBIRNET ILETISIM HIZMETLERI SANAYI VE TICARET LIMITED SIRKETI
• AS20764 CJSC RASCOM
• AS5405 Inter.link GmbH
• AS57463 NetIX Communications JSC
• AS29632 Netassist International EOOD

Adjacent networks

• AS3356 Level 3 Parent, LLC
• AS202 Level 3 Parent, LLC
• AS6939 Hurricane Electric LLC
• AS8262 Evolink EAD
• AS8218 Zayo Infrastructure France SA
• AS8280 SYNAPSECOM S.A. Provider of Telecommunications and Internet Services
• AS24482 SG.GS
• AS5405 Inter.link GmbH
• AS57463 NetIX Communications JSC
• AS20764 CJSC RASCOM
• AS208972 GIBIRNET ILETISIM HIZMETLERI SANAYI VE TICARET LIMITED SIRKETI
• AS29632 Netassist International EOOD

Internet exchanges

• NetIX — Sofia, Bulgaria
• InterLAN-IX — Bucharest, Romania
• Bulgarian Internet eXchange — Sofia, Bulgaria