OpenSSL: Membuat RootCA di Ubuntu
sumber: https://networklessons.com/uncategorized/openssl-certification-authority-ca-ubuntu-server/
Overview
OpenSSL adalah perpustakaan open-source gratis yang dapat Anda gunakan untuk sertifikat digital. Salah satu hal yang dapat Anda lakukan adalah membangun CA Anda sendiri (Certificate Authority).
Selain situs web dan HTTPS, ada beberapa aplikasi / layanan lain yang bisa menggunakan sertifikat digital. Sebagai contoh:
- VPNs: di samping menggunakan kunci pra-berbagi anda dapat menggunakan sertifikat digital untuk otentikasi.
- Wireless: WPA 2 enterprise menggunakan sertifikat digital untuk otentikasi klien dan / atau otentikasi server menggunakan PEAP atau EAP-TLS.
Daripada membayar perusahaan seperti Verisign untuk semua sertifikat digital Anda. Ini bisa berguna untuk membangun CA Anda sendiri untuk beberapa aplikasi anda. Dalam pelajaran ini, Anda akan belajar bagaimana membuat CA anda sendiri.
Configuration
In my examples, I will use a Ubuntu server, the configuration of openSSL will be similar though on other distributions like CentOS.
Prerequisites
Sebelum mengkonfigurasi OpenSSL, kita akan mengkonfigurasi hostname/FQDN secara benar, dan memastikan waktu (time), tanggal (date) dan timezone adalah benar.
Melihat hostname
vmware@ca:~$ hostname ca
Cek FQDN:
vmware@ca:~$ hostname -f ca
Ubah FQDN; anda perlu mengedit file berikut:
$ sudo vi /etc/hosts
Ubah kalimat
127.0.1.1 ca
Menjadi
127.0.1.1 ca.networklessons.local ca
Verifikasi hostname dan FQDN lagi
vmware@ca:~$ hostname ca
vmware@ca:~$ hostname -f ca.networklessons.local
hostname dan FQDN sekarang harusnya ok.
Kita dapat mengkonfigurasi time/date secara manual, akan tetap akan lebih baik jika menggunakan NTP. Kita dapat mensinkronkan waktu menggunakan perintah berikut
sudo apt install ntpdate sudo ntpdate pool.ntp.org 11 Jun 09:33:31 ntpdate[12902]: adjust time server 202.65.114.202 offset 0.002268 sec
Akan lebih baik kalau kita bisa mensinkronkan secara periodik. Install NTP,
$ sudo apt-get install ntp
Secara default Ubuntu server akan menggunakan NTP server pool berikut
$ cat /etc/ntp.conf | grep ubuntu
pool 0.ubuntu.pool.ntp.org iburst pool 1.ubuntu.pool.ntp.org iburst pool 2.ubuntu.pool.ntp.org iburst pool 3.ubuntu.pool.ntp.org iburst pool ntp.ubuntu.com
Kita dapat memverifikasi server mana yang saat ini digunakan menggunakan perintah,
$ ntpq -p
remote refid st t when poll reach delay offset jitter ============================================================================== 0.ubuntu.pool.n .POOL. 16 p - 64 0 0.000 0.000 0.000 1.ubuntu.pool.n .POOL. 16 p - 64 0 0.000 0.000 0.000 2.ubuntu.pool.n .POOL. 16 p - 64 0 0.000 0.000 0.000 3.ubuntu.pool.n .POOL. 16 p - 64 0 0.000 0.000 0.000 ntp.ubuntu.com .POOL. 16 p - 64 0 0.000 0.000 0.000 -mirror2.wowrack 203.160.128.66 2 u 53 64 7 3.331 -1.427 1.697 -resolv1.axarva. 203.160.128.66 2 u 55 64 7 3.598 -2.668 1.771 -ntp.nap.net.id 203.160.128.59 3 u 59 64 7 3.247 2.212 1.688 #180.250.246.110 118.189.138.5 2 u 53 64 7 6.753 -10.279 2.178 -182.253.66.205 103.31.224.224 3 u 58 64 7 16.226 -1.938 1.456 #ntp.uii.net.id 103.1.106.69 2 u 55 64 7 13.195 0.281 1.953 -ns2.jkt.datauta 203.160.128.66 2 u 55 64 7 3.406 -3.792 2.003 +ntp.lipi.go.id 203.160.128.66 2 u 52 64 7 10.542 -0.725 1.642 #mail.lumajangka 103.5.51.210 3 u 56 64 7 16.442 -6.979 1.647 -182.253.66.203 203.89.31.13 3 u 59 64 7 19.566 -3.122 2.984 *203.160.128.132 203.160.128.66 2 u 59 64 7 9.063 -0.988 1.615 -suro.ubaya.ac.i 203.160.128.66 2 u 56 64 7 15.362 -3.050 2.038 +203.114.224.31 203.114.224.252 3 u 60 64 7 15.204 -3.430 2.117 #alphyn.canonica 132.246.11.231 2 u 60 64 7 267.479 5.842 1.658
Server kita sudah di konfigurasi dengan baik.
Konfigurasi OpenSSL
OpenSSL menggunakan file konfigurasi yang mudah dibaca. Ada beberapa hal yang akan kita ubah di dalamnya:
vi /usr/lib/ssl/openssl.cnf
Carilah bagian berikut ini:
[ CA_default ] dir = ./demoCA
Dan ubahlah, jadi seperti berikut ini:
[ CA_default ]
dir = /root/ca
Folder "/ root / ca" adalah tempat kami menyimpan kunci pribadi dan sertifikat kami.
Anda mungkin juga ingin melihat kebijakan default:
[ policy_match ] countryName = match stateOrProvinceName = match organizationName = match organizationalUnitName = optional commonName = supplied emailAddress = optional
Beberapa bidang seperti negara, negara bagian / provinsi, dan organisasi harus sesuai. Jika anda membangun CA anda untuk lingkungan laboratorium seperti saya, maka anda mungkin ingin mengubah beberapa nilai berikut:
[ policy_match ] countryName = match stateOrProvinceName = optional organizationName = optional organizationalUnitName = optional commonName = supplied emailAddress = optional
Saya telah mengubahnya sehingga hanya nama negara yang harus dicocokkan.
Root CA
Hal pertama yang harus kita lakukan adalah membuat root CA. Ini terdiri dari kunci pribadi dan root certificate. Kedua item ini adalah "identitas" CA kita.
Mari beralih ke pengguna root:
$ sudo su
Kami akan membuat folder baru yang menyimpan semua kunci dan sertifikat:
# mkdir /root/ca
Di folder baru ini kita harus membuat beberapa sub-folder tambahan:
# cd /root/ca # mkdir newcerts certs crl private requests
Kami juga membutuhkan dua file. Yang pertama disebut "index.txt". Di sinilah OpenSSL melacak semua sertifikat yang ditandatangani:
# touch index.txt
File kedua disebut "serial". Setiap sertifikat yang ditandatangani akan memiliki nomor seri. Saya akan mulai dengan nomor 1234:
# echo '1234' > serial
Semua folder dan file ada di tempat. Mari buat private key root:
# openssl genrsa -aes256 -out private/cakey.pem 4096
Generating RSA private key, 4096 bit long modulus ..++ ..................++ e is 65537 (0x10001) Enter pass phrase for private/cakey.pem: Verifying - Enter pass phrase for private/cakey.pem:
Kunci privat root yang saya hasilkan adalah 4096 bit dan menggunakan enkripsi AES 256 bit. Ini disimpan dalam folder private menggunakan nama file "cakey.pem".
Siapa pun yang memiliki private key root akan dapat membuat sertifikat yang bisa dipercaya. Simpan file ini dengan aman!
Sekarang kita bisa menggunakan root private key untuk membuat sertifikat root:
# openssl req -new -x509 -key /root/ca/private/cakey.pem -out cacert.pem -days 3650 -set_serial 0
Enter pass phrase for /root/ca/private/cakey.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]:NL State or Province Name (full name) [Some-State]:North-Brabant Locality Name (eg, city) []:Tilburg Organization Name (eg, company) [Internet Widgits Pty Ltd]:Networklessons Organizational Unit Name (eg, section) []: Common Name (e.g. server FQDN or YOUR name) []:CA.networklessons.local Email Address []:admin@networklessons.local
Sertifikat root akan disimpan sebagai nama file "cacert.pem" dan berlaku selama 10 tahun.
Create a certificate
Our root CA is now up and running. Normally when you want to install a certificate on a device (a web server for example), then the device will generate a CSR (Certificate Signing Request). This CSR is created by using the private key of the device.
On our CA, we can then sign the CSR and create a digital certificate for the device.
Another option is that we can do everything on our CA. We can generate a private key, CSR and then sign the certificate…everything “on behalf” of the device.
That’s what I am going to do in this example; it’s a good way to test if your CA is working as expected.
I’ll generate a private key, CSR and certificate for an imaginary “web server”.
Let’s use the requests folder for this:
# cd /root/ca/requests/
First, we have to generate a private key:
# openssl genrsa -aes256 -out some_serverkey.pem 2048 Generating RSA private key, 2048 bit long modulus ..............................+++ ....+++ e is 65537 (0x10001) Enter pass phrase for some_server.pem: Verifying - Enter pass phrase for some_server.pem:
The private key will be 2048 bit and uses AES 256 bit encryption. With the private key, we can create a CSR:
root@ca:~/ca/requests# openssl req -new -key some_serverkey.pem -out some_server.csr Enter pass phrase for some_serverkey.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]:NL State or Province Name (full name) [Some-State]:North-Brabant Locality Name (eg, city) []:Tilburg Organization Name (eg, company) [Internet Widgits Pty Ltd]:Networklessons Organizational Unit Name (eg, section) []: Common Name (e.g. server FQDN or YOUR name) []:some_server.networklessons.local Email Address []:admin@networklessons.local Please enter the following 'extra' attributes to be sent with your certificate request A challenge password []: An optional company name []:
Now we can sign the CSR that we just created:
# openssl ca -in some_server.csr -out some_server.pem
Using configuration from /usr/lib/ssl/openssl.cnf
Enter pass phrase for /root/ca/private/cakey.pem:
Check that the request matches the signature
Signature ok
Certificate Details:
Serial Number: 4660 (0x1234)
Validity
Not Before: Apr 1 09:08:59 2016 GMT
Not After : Apr 1 09:08:59 2017 GMT
Subject:
countryName = NL
stateOrProvinceName = North-Brabant
organizationName = Networklessons
commonName = some_server.networklessons.local
emailAddress = admin@networklessons.local
X509v3 extensions:
X509v3 Basic Constraints:
CA:FALSE
Netscape Comment:
OpenSSL Generated Certificate
X509v3 Subject Key Identifier:
57:A7:7A:41:3E:3F:B3:EE:0D:CF:46:D0:A7:A5:9B:46:92:D1:F0:AD
X509v3 Authority Key Identifier:
keyid:1B:38:B6:9F:82:46:72:5A:04:07:76:C2:DA:A5:5D:EB:95:83:81:30
Certificate is to be certified until Apr 1 09:08:59 2017 GMT (365 days)
Sign the certificate? [y/n]:y
1 out of 1 certificate requests certified, commit? [y/n]y
Write out database with 1 new entries
Data Base Updated
That’s all there is to it. The “some_server.pem” file is the signed digital certificate for our web server. If you want you can delete the CSR, move the private key to the “private” folder, and move the new certificate to the “certs” folder:
# rm some_server.csr # mv some_serverkey.pem /root/ca/private/ # mv some_server.pem /root/ca/certs/
The “some_server.pem” certificate can now be installed on your web server.
Security
Protecting your CA is important. Anyone that has access to the private key of the CA will be able to create trusted certificates.
One of the things you should do is reducing the permissions on the entire /root/ca folder so that only our root user can access it:
# chmod -R 600 /root/ca
In this example, we used the root CA to sign the certificate of an imaginary web server directly. This is fine for a lab environment but for a production network, you should use an intermediate CA.
The intermediate CA is another server that signs certificates on behalf of the root CA.
The root CA signs the certificate of the intermediate CA. You can then take the root CA offline which reduces the chance of anyone getting their hands on your root private key.
Verification
We created some private keys and generated some certificates. Let’s take a closer look at some of our work.
Here’s the index.txt file:
# cat /root/ca/index.txt V 170401090859Z 1234 unknown /C=NL/ST=North-Brabant/O=Networklessons/CN=some_server.networklessons.local/emailAddress=admin@networklessons.local
Above you can see the certificate that we created for our web server. It also shows the serial number that I stored in the serial file. The next certificate that we sign will get another number:
# cat /root/ca/serial 1235
Let’s take a closer look at the certificates. We can verify them with OpenSSL, but it might be nice to see them on your computer. I’ll use a Windows computer for this.
Windows doesn’t recognize the .PEM file extension so you might want to rename your certificates to .CRT.
Here’s the root certificate:
OpenSSL Root Certificate
Above you can see the name of our root CA and the validity (10 years). If we want to trust certificates that are signed by our root CA, then we’ll have to install this certificate. Here’s how:
OpenSSL install root certificate
Hit the Install Certificate button and you will see this wizard:
openssl user or machine
It’s up to you if you want to install it for your current user or the entire computer. Click Next to continue:
openssl trusted root certificate store
Make sure you select the Trusted Root Certification Authorities store and click Next and Finish:
openssl finish install root certificate
Windows will give you one more big security warning, click Yes to continue:
openssl root certificate security warning
The root certificate is now installed and trusted. Now open the certificate that we assigned to “some server”:
openssl server certificate trusted
Above you can see that it was issued by our root CA, it’s valid for one year. When you look at the certification path then you can see that Windows trusts the certificate:
openssl server certification path
This is looking good. If a web server would present this certificate to your computer, then it will trust it from now on.
Conclusion
You have now learned how to build your own CA using OpenSSL and are ready to sign certificates for your servers, routers, firewalls, clients or any other devices that you have.
I hope you enjoyed this lesson, if you have any questions feel free to ask!