# Agent instance fails to start with IPSec enabled

**URL:** <https://forums.suse.com/t/agent-instance-fails-to-start-with-ipsec-enabled/3596>\
**Category:** Rancher 1.x\
**Created:** [August 1, 2016, 3:20pm UTC](https://forums.suse.com/t/agent-instance-fails-to-start-with-ipsec-enabled/3596 "2016-08-01T15:20:39Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![cookandy](https://avatars.discourse-cdn.com/v4/letter/c/e495f1/32.png) [@cookandy](https://forums.suse.com/u/cookandy)\
**Post date:** [August 1, 2016, 3:20pm UTC](https://forums.suse.com/t/agent-instance-fails-to-start-with-ipsec-enabled/3596/1 "2016-08-01T15:20:39Z")

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Hello,

I am having trouble spawning containers when running a rancher agent on a server with IPSec enabled. When I start the container, I see this in the logs:

`APIError: 500 Server Error: Internal Server Error ("driver failed programming external connectivity on endpoint e3d55e88-6ba7-481f-9bb8-484a2b7948c0 (c4f4539de9660e45a3a5c6b064ca1c0dd761a5528f5971f24a537c5560cd360d): Error starting userland proxy: listen udp 0.0.0.0:4500: bind: address already in use")`

It’s true that port `4500` is already used by IPSec.

How can I allow rancher to start containers while running IPSec? The Rancher server and agent can communicate just fine over IPSec - I just can’t spawn new containers. Any ideas?

BTW - I’m running Ubuntu 16 with Docker 1.12.

Seems very similar to this post: [Network Agent fails to start](http://forums.suse.com/t/network-agent-fails-to-start/774)

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**Author:** ![denise](https://avatars.discourse-cdn.com/v4/letter/d/82dd89/32.png) [@denise](https://forums.suse.com/u/denise)\
**Post date:** [August 3, 2016, 5:51pm UTC](https://forums.suse.com/t/agent-instance-fails-to-start-with-ipsec-enabled/3596/2 "2016-08-03T17:51:27Z")

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This is a feature request:

[https://github.com/rancher/rancher/issues/2139](https://github.com/rancher/rancher/issues/2139)