# Port flipping

**URL:** <https://community.zeek.org/t/port-flipping/3615>\
**Category:** Development\
**Tags:** development\
**Created:** [May 22, 2015, 11:47am UTC](https://community.zeek.org/t/port-flipping/3615 "2015-05-22T11:47:11Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![Martina\_Balintova](https://avatars.discourse-cdn.com/v4/letter/m/a9a28c/32.png) [@Martina\_Balintova](https://community.zeek.org/u/Martina_Balintova)\
**Post date:** [May 22, 2015, 11:47am UTC](https://community.zeek.org/t/port-flipping/3615/1 "2015-05-22T11:47:11Z")

</div>

Hi Robin,

I have a problem where a connection missing its SYN is not flipped correctly, because the client happened to choose a port that Bro thinks is a server port (IRC, 6666). What is confusing me is the special case in NetSessions::WantConnection() that prevents the flip. Your comments are about avoiding being confused by stealth scans, but I think that the flip will happen in every case except when the client is unlucky enough to use a “server” port number. Given that is most of the time, why have the special case at all?

Martina

---

<div class="post-metadata">

**Author:** ![system](https://canada1.discourse-cdn.com/flex011/uploads/zeek/original/1X/f09d732bc2cc7c7cc7e35db67cf4e1d5233ce7a7.png) [@system](https://community.zeek.org/u/system)\
**Post date:** [May 6, 2022, 3:42pm UTC](https://community.zeek.org/t/port-flipping/3615/2 "2022-05-06T15:42:42Z")

</div>