OpenVPNのインストール

VPNサーバー

pacman -S openvpn

認証局サーバー

pacman -S easy-rsa

cd /etc/easy-rsa
easyrsa init-pki

init-pki complete; you may now create a CA or requests.
Your newly created PKI dir is: /etc/easy-rsa/pki


easyrsa build-ca
Using SSL: openssl OpenSSL 1.1.1d  10 Sep 2019

Enter New CA Key Passphrase: 
Re-Enter New CA Key Passphrase: 
Generating RSA private key, 2048 bit long modulus (2 primes)
...........................+++++
.....................................+++++
e is 65537 (0x010001)
Can't load /etc/easy-rsa/pki/.rnd into RNG
139748243150080:error:2406F079:random number generator:RAND_load_file:Cannot open file:crypto/rand/randfile.c:98:Filename=/etc/easy-rsa/pki/.rnd
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.
-----
Common Name (eg: your user, host, or server name) [Easy-RSA CA]:xxxxxxxx

CA creation complete and you may now import and sign cert requests.
Your new CA certificate file for publishing is at:
/etc/easy-rsa/pki/ca.crt

CAの公開鍵をVPNサーバーに移行

cp /etc/easy-rsa/pki/ca.crt /tmp
chown foo /tmp/ca.crt
scp /tmp/ca.crt foo@hostname-of-openvpn-server:/tmp

VPNサーバー

mv /tmp/ca.crt /etc/openvpn/server/
chown root:root /etc/openvpn/server/ca.crt

pacman -S easy-rsa

cd /etc/easy-rsa
easyrsa init-pki

init-pki complete; you may now create a CA or requests.
Your newly created PKI dir is: /etc/easy-rsa/pki


easyrsa gen-req ［サーバー名？］ nopass

Using SSL: openssl OpenSSL 1.1.1d  10 Sep 2019
Can't load /etc/easy-rsa/pki/.rnd into RNG
139780419302656:error:2406F079:random number generator:RAND_load_file:Cannot open file:crypto/rand/randfile.c:98:Filename=/etc/easy-rsa/pki/.rnd
Generating a RSA private key
..................................................+++++
.................................................................+++++
writing new private key to '/etc/easy-rsa/pki/private/servername.key.TUQccMn1qp'
-----
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.
-----
Common Name (eg: your user, host, or server name) [servername]:yyyyyyyy

Keypair and certificate request completed. Your files are:
req: /etc/easy-rsa/pki/reqs/servername.req
key: /etc/easy-rsa/pki/private/servername.key

cp /etc/easy-rsa/pki/private/servername.key /etc/openvpn/server/

openssl dhparam -out /etc/openvpn/server/dh.pem 2048

openvpn --genkey --secret /etc/openvpn/server/ta.key

クライアントファイルの作成
初期化してなかったら…

# cd /etc/easy-rsa
# easyrsa init-pki

# cd /etc/easy-rsa
# easyrsa gen-req client1 nopass

Using SSL: openssl OpenSSL 1.1.1d  10 Sep 2019
Can't load /etc/easy-rsa/pki/.rnd into RNG
139780419302656:error:2406F079:random number generator:RAND_load_file:Cannot open file:crypto/rand/randfile.c:98:Filename=/etc/easy-rsa/pki/.rnd
Generating a RSA private key
..................................................+++++
.................................................................+++++
writing new private key to '/etc/easy-rsa/pki/private/client1.key.TUQccMn1qp'
-----
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.
-----
Common Name (eg: your user, host, or server name) [client1]:yyyyyyyy

Keypair and certificate request completed. Your files are:
req: /etc/easy-rsa/pki/reqs/client1.req
key: /etc/easy-rsa/pki/private/client1.key

# cp /etc/easy-rsa/pki/reqs/*.req /tmp
# chown foo /tmp/*.req
$ scp /tmp/*.req foo@hostname-of-CA:/tmp

認証局サーバー

# cd /etc/easy-rsa
# easyrsa import-req /tmp/servername.req servername
Using SSL: openssl OpenSSL 1.1.1d  10 Sep 2019

The request has been successfully imported with a short name of: servername
You may now use this name to perform signing operations on this request.

# easyrsa import-req /tmp/client1.req client1
Using SSL: openssl OpenSSL 1.1.1d  10 Sep 2019

The request has been successfully imported with a short name of: client1
You may now use this name to perform signing operations on this request.

# easyrsa sign-req server servername
Using SSL: openssl OpenSSL 1.1.1d  10 Sep 2019


You are about to sign the following certificate.
Please check over the details shown below for accuracy. Note that this request
has not been cryptographically verified. Please be sure it came from a trusted
source or that you have verified the request checksum with the sender.

Request subject, to be signed as a server certificate for 1080 days:

subject=
    commonName                = xxxxxxxx


Type the word 'yes' to continue, or any other input to abort.
  Confirm request details: yes
Using configuration from /etc/easy-rsa/pki/safessl-easyrsa.cnf
Enter pass phrase for /etc/easy-rsa/pki/private/ca.key:
Check that the request matches the signature
Signature ok
The Subject's Distinguished Name is as follows
commonName            :ASN.1 12:'xxxxxxxx'
Certificate is to be certified until Dec  9 05:16:12 2022 GMT (1080 days)

Write out database with 1 new entries
Data Base Updated

Certificate created at: /etc/easy-rsa/pki/issued/servername.crt

# easyrsa sign-req client client1
Using SSL: openssl OpenSSL 1.1.1d  10 Sep 2019


You are about to sign the following certificate.
Please check over the details shown below for accuracy. Note that this request
has not been cryptographically verified. Please be sure it came from a trusted
source or that you have verified the request checksum with the sender.

Request subject, to be signed as a client certificate for 1080 days:

subject=
    commonName                = yyyyyyyy


Type the word 'yes' to continue, or any other input to abort.
  Confirm request details: yes
Using configuration from /etc/easy-rsa/pki/safessl-easyrsa.cnf
Enter pass phrase for /etc/easy-rsa/pki/private/ca.key:
Check that the request matches the signature
Signature ok
The Subject's Distinguished Name is as follows
commonName            :ASN.1 12:'yyyyyyyy'
Certificate is to be certified until Dec  9 05:17:51 2022 GMT (1080 days)

Write out database with 1 new entries
Data Base Updated

Certificate created at: /etc/easy-rsa/pki/issued/client1.crt

認証局からVPNサーバーとクライアントに返却

# cp /etc/easy-rsa/pki/issued/*.crt /tmp
# chown foo /tmp/*.crt
$ scp /tmp/*.crt foo@hostname-of-openvpn_server:/tmp

VPNサーバー

# mv /tmp/servername.crt /etc/openvpn/server/
# chown root:root /etc/openvpn/server/servername.crt

VPNクライアント

ぶっちゃけどこでも構わない

# mkdir /etc/easy-rsa/pki/signed
# mv /tmp/client1.crt /etc/easy-rsa/pki/signed