# Connecting to Catalyst running inside a Docker container via Desktop Paraview

**URL:** https://discourse.paraview.org/t/connecting-to-catalyst-running-inside-a-docker-container-via-desktop-paraview/8451
**Category:** In Situ Support
**Created:** [November 22, 2021, 2:36pm UTC](https://discourse.paraview.org/t/connecting-to-catalyst-running-inside-a-docker-container-via-desktop-paraview/8451 "2021-11-22T14:36:36Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![FeStein](https://discourse.paraview.org/user_avatar/discourse.paraview.org/festein/32/8035_2.png) [@FeStein](https://discourse.paraview.org/u/FeStein)
#### Post date: [November 22, 2021, 2:36pm UTC](https://discourse.paraview.org/t/connecting-to-catalyst-running-inside-a-docker-container-via-desktop-paraview/8451/1 "2021-11-22T14:36:36Z")

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Hello,  
essentially I try to do an in-situ visualization of a fenics/dolfin simulation. At the moment I try to work on getting the pipeline correct in order to be able to simulate inside a docker container (later on singularity on an HPC) and visualize it live via Paraview. For this reason, I use the example scripts provided in the Paraview Catalysts Examples github repo.  
Currently, the simulation and visualization work fine when I use my locally installed Paraview and Dolfin on my machine. I got a docker container with both paraview and dolfin installed and the sample scripts also work inside the container. My problem is, that I can’t connect via Catalyst to the simulation running inside the container. I try to make the port accessible outside the container using the `-p 22222:22222` flag, but each time I try to access the simulation via Catalyst I get the error:

```auto
Socket error in call to bind.Address already in use.
Failed to set up server socket.

```

It seems like forwarding the ports in Docker blocks them for Catalyst, but I don’t know how to resolve the issue. Changing ports did not help.

Thank you for your help