rewrite ^/$ http://ufo.kit.edu/dis/;

location /dis {
    proxy_pass https://192.168.26.211/dis/;
    proxy_set_header Host $host;
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header X-Forwarded-Proto $scheme;
}