The Alps High-Speed Network (HSN) is – by and large – configured with private IP addresses (172.28.0.0/16).  Login nodes have public IP addresses, while a proxy server provides internet access for compute nodes. 

Login nodes

All login nodes have been configured with an additional public IP address. With this configuration, login nodes can access the internet directly. All traffic directed outside the CSCS network will use the public IP address as a source address.

[daint][<user>@daint-ln001 ~]$ ping 9.9.9.9 # ping Quad9 DNS
PING 9.9.9.9 (9.9.9.9) 56(84) bytes of data.
64 bytes from 9.9.9.9: icmp_seq=1 ttl=57 time=3.00 ms
64 bytes from 9.9.9.9: icmp_seq=2 ttl=57 time=2.93 ms
64 bytes from 9.9.9.9: icmp_seq=3 ttl=57 time=2.97 ms


[daint][<user>@daint-ln001 ~]$ curl api.ipify.org # return your public IP address programmatically
148.187.6.19

Please note: traffic directed towards CSCS services will use the private IP addresses. 

Compute nodes

Compute nodes do not have public IP addresses, but can use CSCS proxy servers to access the internet.

To this end, the following environment variables have been configured on all compute nodes (uppercase and lowercase):

https_proxy=http://proxy.cscs.ch:8080
http_proxy=http://proxy.cscs.ch:8080
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
HTTPS_PROXY=http://proxy.cscs.ch:8080
HTTP_PROXY=http://proxy.cscs.ch:8080
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

SSH/Github access

To access GitHub or other SSH services outside of the CSCS network, configure your .ssh/config file as the following:

.ssh/config
Match Host *,!148.187.0.0/16,!192.168.0.0/16,!172.16.0.0/12,!10.0.0.0/8 exec "hostname -I | grep -vqF 148.187."
    ProxyCommand nc -X connect -x proxy.cscs.ch:8080 %h %p



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