RFC 4787: Network Address Translation (NAT) Behavioral Requirements for Unicast UDP (BCP 127)

Publisher

IETF / RFC Editor

URL

https://www.rfc-editor.org/rfc/rfc4787.html

Published

2007-01-01

Updated

unknown

Accessed

2026-09-25

HTTP status

200

License

IETF Trust Legal Provisions; RFC text may be reproduced with attribution; short excerpts and locators only

Source notes citing this source

• RFC 4787 warns that NAT ALGs may interfere with UNSAF methods or protocols that try to be NAT-aware and must be used with extreme caution. in context
• RFC 4787 (BCP 127) REQ-10 states that NAT ALGs for UDP-based protocols SHOULD be turned off, so that they do not interfere with UNSAF NAT traversal mechanisms and so that integrity protection of UDP communications is possible. in context
• RFC 4787 observes that some NATs keep ALGs such as the SIP ALG permanently on, some turn them on by default but allow them to be turned off, and some leave them off by default but allow them to be turned on. in context
• RFC 4787 REQ-10 a) recommends that a NAT that includes ALGs let the administrator enable or disable each ALG separately. in context

Cite this source record

APA

WarmTransfer. (2007, January 1). RFC 4787: Network Address Translation (NAT) Behavioral Requirements for Unicast UDP (BCP 127). WarmTransfer. https://warmtransfer.net/knowledge/sources/rfc-4787-nat-udp-behavior

BibTeX

@misc{warmtransfer-rfc-4787-nat-udp-behavior,
  title  = {RFC 4787: Network Address Translation (NAT) Behavioral Requirements for Unicast UDP (BCP 127)},
  author = {{WarmTransfer}},
  year   = {2007},
  url    = {https://warmtransfer.net/knowledge/sources/rfc-4787-nat-udp-behavior},
  note   = {IETF / RFC Editor, accessed 2026-09-25}
}