Encrypting Communication between Web Node and Compute Node in Linux


This article walks you through the steps for encrypting the traffic between web nodes and compute nodes in Linux using self-signed certificates. If a compute node is inside the web node's trust boundary, then encryption of this piece isn't needed. However, if the compute node resides outside of the trust boundary, consider using the compute node certificate to encrypt the traffic between the web node and compute node. As a prerequisite, you can spin a 1-webnode-1-computenode enterprise configuration using ARM Template from here.

On each Linux machine hosting a compute node:

Generate and Install self-signed certificates using the following commands:

For Single Compute Node, use IP Address as Certificate Subject Name.

For multiple compute nodes, use DNS Suffix as Certificate Subject Name. 

Example: say you have 2 compute nodes CN1.contoso.microsoft.com, CN2.contoso.microsoft.com, certificate subject name will be CN=contoso.microsoft.com.

cd /etc/ssl/certs
openssl genrsa -out privateKey.pem 2048
openssl req -new -x509 -key privateKey.pem -out publicCert.pem -days 3650 -nodes -subj "/CN=10.0.1.4"
openssl x509 -noout -hash -in publicCert.pem
ln -s publicCert.pem 0c73457b.0

Install nginx

Ubuntu:

apt-get install -y nginx

RedHat:

yum clean all
yum makecache fast
yum -y install https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
yum install -y nginx

CentOS:

yum install -y epel-release
yum install -y nginx

Modify nginx.conf

Location of nginx.conf
Ubuntu: /etc/nginx/sites-enabled/default
RedHat and CentOS: /etc/nginx/nginx.conf

Modify the file in above location to the following contents :

server {
    listen 443 ssl;
    ssl_certificate /etc/ssl/certs/publicCert.pem;
    ssl_certificate_key /etc/ssl/private/privateKey.pem;
    server_name _;
    location / {
        proxy_pass http://127.0.0.1:12805/;
    }
}

Restart nginx

Ubuntu:

service nginx start
update-rc.d nginx defaults

RedHat:

systemctl start nginx
systemctl enable nginx
iptables –flush

CentOS:

systemctl start nginx
systemctl enable nginx

Launch the administrator's utility and restart the compute node

Check Compute Node status using curl

curl https://10.0.1.4/status

Should give a response like this:

{
 "statusCode": 0,
 "components": null,
 "details": {
     "rMaxPoolSize": 500,
     "rActiveShellCount": 0,
     "rCurrentPoolSize": 5,
     "rCanOpenShell": "True",
     "apiVersion": "1.0",
     "logPath": "/usr/lib64/microsoft-r/rserver/o16n/9.1.0/Microsoft.RServer.ComputeNode/logs"
 }
}

On each Linux machine hosting a web node:

Copy paste the publicCert.pem and certificate authority into /etc/ssl/certs

scp root@10.0.1.4:/etc/ssl/certs/publicCert.pem /etc/ssl/certs
scp root@10.0.1.4:/etc/ssl/certs/0c73457b.0 /etc/ssl/certs

Open appsettings.json and modify the URIs :

"Uris": {
    "Values": [ "https://10.0.1.4" ]
}

NOTE: If you have multiple compute nodes, make sure to enter all compute nodes information in the URI values. For example:

"Uris": {
    "Values": [ "https://CN1.contoso.microsoft.com", "https://CN2.contoso.microsoft.com" ]
}

Launch the administrator's utility and restart the web node.

Verify the configuration by running diagnostic test on the web node.

NOTE: Self-Signed Certificates are NOT recommended for production usage. Please obtain certificate from Trusted Certificate Authorities for production usage.

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