#### Pre-Submission Checklist - [x] Commit message has the format required by CONTRIBUTING guide - [x] Commits are split per component (core, individual modules, libs, utils, ...) - [x] Each component has a single commit (if not, squash them into one commit) - [x] No commits to README files for modules (changes must be done to docbook files in doc/ subfolder, the README file is autogenerated)

#### Type Of Change - [x] Small bug fix (non-breaking change which fixes an issue) - [ ] New feature (non-breaking change which adds new functionality) - [ ] Breaking change (fix or feature that would change existing functionality)

#### Checklist: - [x] PR should be backported to stable branches - [x] Tested changes locally - [x] Related to issue #2459

#### Description There's a small regression after #2497.

If SDP didn't have an "a=rtcp" header (RFC1889 behavior), Kamailio had thrown an Error `can't extract 'a=rtcp' IP from the SDP` on every INVITE. After the PR Kamailio does not flood into log.

Please take into account IPv6 address parser after the commit.

You can view, comment on, or merge this pull request online at:

https://github.com/kamailio/kamailio/pull/2737

-- Commit Summary --

* nathelper: fix_nated_sdp added ignoring RFC3605-param if omitted

-- File Changes --

M src/modules/nathelper/nathelper.c (22)

-- Patch Links --

https://github.com/kamailio/kamailio/pull/2737.patch https://github.com/kamailio/kamailio/pull/2737.diff