1027
Summary
- // if you see it open
- The RFC describes UDP encapsulation between clients and ISP relays; restrict access to intended peers when deliberately operating 6a44. No deployment or security incident evidence was supplied.
- // common applications
- 6a44 client software6a44 relay software Protocol design uses UDP bubbles between clients and relays and carries encapsulated IPv6 packets; no observed traffic data was supplied.
About port 1027/udp.
UDP port 1027 is assigned to 6a44, a protocol for carrying IPv6 connectivity through IPv4 NAT equipment. RFC 6751 describes clients exchanging UDP encapsulated packets with ISP operated relays. The evidence establishes the protocol design and registry assignment, but does not establish whether it is deployed today or how often traffic appears. (IANA; RFC 6751.)
6a44 was designed for IPv4 only customer networks whose providers cooperate by operating relays and assigning network specific IPv6 prefixes. Clients use UDP bubbles to establish and maintain the tunnel and receive an IPv6 prefix; IPv6 packets for destinations beyond the local customer site travel encapsulated over UDP/IPv4. The RFC calls this a temporary, last resort approach for IPv6 connectivity and is Experimental, not Standards Track. (RFC 6751.)
RFC 6751 describes 6a44 as an experimental IPv6 tunneling design involving clients and ISP relays over UDP/1027. Actual deployment, traffic prevalence, exposure, current operators, and malware associations are Unknown. Apply access controls according to the deployment’s requirements.
- Protocol
- UDP/1027 is assigned to 6a44, an Experimental IPv6 tunneling design for NAT44 environments. [Confirmed]
- Intended peers
- 6a44 clients communicate with participating ISP relays; the RFC describes ISP cooperation. [Confirmed]
- Exposure guidance
- Avoid broad public access; restrict to intended peers when deliberately operating 6a44. [Likely]
- Observed deployment
- Unknown from the supplied evidence. [Unknown]
- IANA service
- 6a44 — “IPv6 Behind NAT44 CPEs.” [Confirmed] — https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.csv
Primary use
UDP encapsulation for IPv6 connectivity through IPv4-to-IPv4 NAT customer equipment, using participating ISP relays.
Malware associations
Unknown; the supplied sources do not establish any association.
- RFC reference
- RFC 6751, Experimental Protocol; not an Internet Standards Track specification. [Confirmed] — https://www.rfc-editor.org/rfc/rfc6751.txt
- Deployment and prevalence
- Unknown; the supplied sources contain no deployment or traffic measurements. [Unknown] — https://www.rfc-editor.org/rfc/rfc6751.txt
Service assignments.
| Name | Protocol | Description | Open frequency |
|---|---|---|---|
| IIS | TCP | 6a44 | 0.67% |
Service assignments from the IANA Service Name and Transport Protocol Port Number Registry, with open-frequency data from nmap-services.