delete information about proxy server (#159)

Author: finkandreas

docs/guides/internet-access.md

@@ -2,58 +2,19 @@
 # Internet Access on Alps
 
 The [Alps network][ref-alps-hsn] is mostly configured with private IP addresses (`172.28.0.0/16`).
-Login nodes have public IP addresses which means that they can directly access the internet, while a proxy server provides internet access for compute nodes.
-
-??? info "Compute node proxy configuration"
-
-    Compute nodes are configured with the following environment variables to use the proxy server:
-    
-    ```bash
-    export https_proxy='http://proxy.cscs.ch:8080'
-    export http_proxy='http://proxy.cscs.ch:8080'
-    export no_proxy='.local, .cscs.ch, localhost, 148.187.0.0/16, 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16'
-    export HTTPS_PROXY='http://proxy.cscs.ch:8080'
-    export HTTP_PROXY='http://proxy.cscs.ch:8080'
-    export NO_PROXY='.local, .cscs.ch, localhost, 148.187.0.0/16, 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16'
-    ```
+Login nodes have public IP addresses which means that they can directly access the internet, while compute nodes access the internet through NAT.
 
 !!! warning "Public IPs are a shared resource"
-    Be aware that public IPs, whether on login nodes or through the proxy, are essentially a shared resource.
+    Be aware that public IPs, whether on login nodes or through NAT, are essentially a shared resource.
     Many services will rate limit or block usage based on the IP address if abused.
     An example is pulling container images from Docker Hub.
     [Authenticating with Docker Hub][ref-ce-third-party-private-registries] makes their rate limit apply per user instead.
 
-## Using SSH through the proxy server 
-
-While use of the proxy server is transparent for most use cases, others need additional configuration for compute nodes.
-An example is cloning git repositories from GitHub over SSH.
-Cloning over https works without additional configuration.
-To make SSH use the proxy server, add the following to your `~/.ssh/config` file:
-
-``` title="~/.ssh/config"
-Match Host *,!148.187.0.0/16,!192.168.0.0/16,!172.16.0.0/12,!10.0.0.0/8exec "hostname -I | grep -vqF 148.187."
-    ProxyCommand nc -X connect -x proxy.cscs.ch:8080 %h %p
-```
-
-This configuration takes into account that login and compute nodes require a different setup.
-
-??? warning "Error message when cloning without the proxy set up for SSH"
-    When cloning a git repository without the correct SSH configuration, cloning will time out as follows:
-    ```bash
-    [daint][<user>@daint-ln001 ~]$ git clone [email protected]:open-mpi/ompi.git
-    Cloning into 'ompi'...
-    ssh: connect to host github.com port 22: Connection timed out
-    fatal: Could not read from remote repository.
-
-    Please make sure you have the correct access rights
-    and the repository exists.
-    ```
-
 ## Accessing the public IP of a node
 
 When on a login node configured with a public IP address, you can retrieve the public IP address for example as follows:
 
-```bash
-[daint][<user>@daint-ln001 ~]$ curl api.ipify.org
+```console
+$ curl api.ipify.org
 148.187.6.19
 ```