This workshop will simulate the scenario in how we can use PKI to make secure communication. All this session we work on terminal, you can following in step-by-step.
In the late session, we learned about how to use public/private keys in an easy case.
I explained the workshop to implement a solution. Then, We upgrade to an advanced workshop
to understand how to implement public/private CA intermediate servers.
If you are not read previous topic, you can go to:
Prerequisite
- OpenSSL
- cURL
- Docker
- tree
Create root CA certificate
In first thing, we will generate simple self-sign root CA certificate with following step:
- Create SSL private key
$ openssl genrsa -out rootCAkey.pem 4096
Generating RSA private key, 4096 bit long modulus (2 primes)
.........................................++++
.........++++
e is 65537 (0x010001)
We generate random keys with 4,096 character and you can use other lengths like 1024, 2048, 8192, or ETC. You can increase or decrease your key length to optimize cpu power to process them.
- Create Certificate from private key
$ openssl req -x509 -sha256 -new -nodes -key rootCAkey.pem \
-days 14 -out rootCAcert.pem
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [AU]:TH
State or Province Name (full name) [Some-State]:Bangkok
Locality Name (eg, city) []:BangKhea
Organization Name (eg, company) [Internet Widgits Pty Ltd]:Opsta Thailand
Organizational Unit Name (eg, section) []:DevOps
Common Name (e.g. server FQDN or YOUR name) []:OpstaRootCA
Email Address []:watcharin@opsta.co.th
For the previous command, I request a new certificate file with some information. I use the digest algorithm
SHA-256
and set it to expire before 14 days. It shows a prompt on your terminal for adding more information. You can see an example above.
- Now, we can verify own root CA
openssl x509 -text -in rootCAcert.pem
You can see your certificate information. Then go to the next step to create a chain certificate.
Create server certificate with issuer
- Generate random private key with same step root CA
# You can replace rsaServerKey.pem to your name
# And can change key size from 2048 to other length
$ openssl genrsa -out rsaServerKey.pem 2048
Generating RSA private key, 2048 bit long modulus (2 primes)
......................................................................+++++
...............+++++
e is 65537 (0x010001)
- Create CNF file that provide meta data for CSR
# req.cnf
[req]
req_extensions = v3_req
distinguished_name = dn
prompt = no
[dn]
CN = ssl-lab.example.local
C = TH
L = Bangkok
O = Opsta Thailand
OU = DevOps
[v3_req]
subjectAltName = @san_names
[san_names]
DNS.1 = ssl-lab.example.local
DNS.2 = localhost
DNS.3 = 127.0.0.1
Provide simple configuration to create CSR file. This file has SAN(Subject Alternative Name) with 3 names in
[san_names]
. For@san_names
, I use for extend alternative name for server.
- Generate CSR certificate
$ openssl req -new -out req.csr -key rsaServerKey.pem -sha256 -config req.cnf
$ cat req.csr
-----BEGIN CERTIFICATE REQUEST-----
MIIC9zCCAd8CAQAwaTEeMBwGA1UEAwwVc3NsLWxhYi5leGFtcGxlLmxvY2FsMQsw
CQYDVQQGEwJUSDEQMA4GA1UEBwwHQmFuZ2tvazEXMBUGA1UECgwOT3BzdGEgVGhh
aWxhbmQxDzANBgNVBAsMBkRldk9wczCCASIwDQYJKoZIhvcNAQEBBQADggEPADCC
…
k9jkEKhPeICqJgHLbyiEcEc9xaPTMPb35cBQT8irnUq1+WbQamhWDIBmwzDHCSyf
jCK672ACRleQCj8kk5l+dOB0wzWEaDcCoQNwIwqg2RpfDKc1lHARroBzm1P/4grg
NaF5EYJJWhXUXGKq68meHpCTGzgC7M06rwBdOR+8l0GIUZ5K25MvNg3+ZA==
-----END CERTIFICATE REQUEST-----
- Verify CSR information, we focus on Requested Extension.
$ openssl req -in req.csr -noout -text
…
Requested Extensions:
X509v3 Subject Alternative Name:
DNS:ssl-lab.example.local, DNS:localhost, DNS:127.0.0.1
- Create trusted certificate with root CA with CSR file
$ openssl x509 -req -sha256 -in req.csr -CA ../rootCAcert.pem \
-extfile <(printf "subjectAltName=DNS:ssl-lab.example.local,DNS:localhost") \
-CAkey ../rootCAkey.pem -CAcreateserial -out CertServer.pem -days 7
…
Signature ok
subject=CN = ssl-lab.example.local, C = TH, L = Bangkok, O = Opsta Thailand, OU = DevOps
Getting CA Private Key
We create trusted certificates with digest algorithm
SHA-256
and create root CA serials that track how many certificates were issued with-CAcreateserial
, so if not the first certificate you will use-CAserial
instead. Then, this certificate will stay for 7 days only.
- Verify certificate information that should have issuer
$ openssl x509 -text -in CertServer.pem
…
Issuer: C = TH, ST = Bangkok, L = BangKhea, O = Opsta Thailand, OU = DevOps, CN = OpstaRootCA, emailAddress = watcharin@opsta.co.th
We will see Issuer information under Certificate >> Data.
Run demo web server
Now you can replace this certificate and private key with the previous session (also topic name little-step-to-use-pki-easiest) and test again. You will install your custom root CA to your browser or machine to see a difference between a single self-signed certificate and certificate with CA issuer.
Run demo web server
-
Create Dockerfile with simple configuration
FROM nginx:1.20-alpine ADD default.conf /etc/nginx/conf.d/default.conf COPY ssl /etc/nginx/ssl RUN chown -R 0:0 /etc/nginx/ssl \ && chown -R 0:0 /etc/nginx/conf.d/default.conf
-
Create Nginx site configuration in following code
server { listen 80; server_name localhost ssl-lab.example.local; return 301 https://localhost:8443$request_uri; } server { listen 443 ssl; server_name localhost ssl-lab.example.local; keepalive_timeout 70; ssl_certificate /etc/nginx/ssl/CertServer.pem; ssl_certificate_key /etc/nginx/ssl/rsaServerKey.pem; ssl_protocols TLSv1.1 TLSv1.2; ssl_prefer_server_ciphers off; location / { root /usr/share/nginx/html; index index.html index.htm; } error_page 500 502 503 504 /50x.html; location = /50x.html { root /usr/share/nginx/html; } }
-
Start docker with default options
docker build -t nginx-ca:demo . docker run -it --rm -p 8080:80 -p 8443:443 nginx-ca:demo
-
Use cUrl with verbose argument to verify
$ curl -vIL --cacert ../rootCA/rootCAcert.pem -XGET https://localhost:8443 * Trying 127.0.0.1:8443... * Connected to localhost (127.0.0.1) port 8443 (#0) * ALPN, offering h2 * ALPN, offering http/1.1 * CAfile: rootCA/rootCAcert.pem * CApath: /etc/ssl/certs * TLSv1.0 (OUT), TLS header, Certificate Status (22): * TLSv1.3 (OUT), TLS handshake, Client hello (1): * TLSv1.2 (IN), TLS header, Certificate Status (22): * TLSv1.3 (IN), TLS handshake, Server hello (2): * TLSv1.2 (IN), TLS header, Certificate Status (22): * TLSv1.2 (IN), TLS handshake, Certificate (11): * TLSv1.2 (IN), TLS header, Certificate Status (22): * TLSv1.2 (IN), TLS handshake, Server key exchange (12): * TLSv1.2 (IN), TLS header, Certificate Status (22): * TLSv1.2 (IN), TLS handshake, Server finished (14): * TLSv1.2 (OUT), TLS header, Certificate Status (22): * TLSv1.2 (OUT), TLS handshake, Client key exchange (16): * TLSv1.2 (OUT), TLS header, Finished (20): * TLSv1.2 (OUT), TLS change cipher, Change cipher spec (1): * TLSv1.2 (OUT), TLS header, Certificate Status (22): * TLSv1.2 (OUT), TLS handshake, Finished (20): * TLSv1.2 (IN), TLS header, Finished (20): * TLSv1.2 (IN), TLS header, Certificate Status (22): * TLSv1.2 (IN), TLS handshake, Finished (20): * SSL connection using TLSv1.2 / ECDHE-RSA-AES256-GCM-SHA384 * ALPN, server accepted to use http/1.1 * Server certificate: * subject: CN=ssl-lab.example.local; C=TH; L=Bangkok; O=Opsta Thailand; OU=DevOps * start date: Sep 16 06:36:23 2022 GMT * expire date: Oct 16 06:36:23 2022 GMT * subjectAltName: host "localhost" matched cert's "localhost" * issuer: C=TH; ST=Bangkok; O=Opsta Thailand; OU=DevOps; CN=OpstaRootCA; emailAddress=watcharin@opsta.co.th * SSL certificate verify ok. * TLSv1.2 (OUT), TLS header, Supplemental data (23): > GET / HTTP/1.1 > Host: localhost:8443 > User-Agent: curl/7.81.0 > Accept: */* > * TLSv1.2 (IN), TLS header, Supplemental data (23): * Mark bundle as not supporting multiuse < HTTP/1.1 200 OK HTTP/1.1 200 OK < Server: nginx/1.20.2 Server: nginx/1.20.2 < Date: Mon, 19 Sep 2022 02:57:09 GMT Date: Mon, 19 Sep 2022 02:57:09 GMT < Content-Type: text/html Content-Type: text/html < Content-Length: 612 Content-Length: 612 < Last-Modified: Tue, 16 Nov 2021 15:04:23 GMT Last-Modified: Tue, 16 Nov 2021 15:04:23 GMT < Connection: keep-alive Connection: keep-alive < ETag: "6193c877-264" ETag: "6193c877-264" < Accept-Ranges: bytes Accept-Ranges: bytes < * Excess found: excess = 612 url = / (zero-length body) * Connection #0 to host localhost left intact
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