OpenVPNのインストール

Raspberry piのArchlinux化をもくろみ、ArchlinuxでVPNサーバーを立ち上げようかと思っています。
そこで、まずはVirtualBoxでOpenVPNを使用して、VPNサーバーを立ち上げてみました。

VPNサーバーと認証局サーバーを分離している前提で、手順を上げています。
もし、一緒にしているなら上手いこと読み替えてください。

鍵の準備

VPNを使用するにあたり、認証局の設立やら共通鍵の作成やら鍵ペアの作成やら色々していきます。

認証局の設立（認証局サーバー）

認証局にするサーバーに以下のコマンドを実行して「Easy-RSA」をインストールします。

# pacman -S easy-rsa

インストールしたら「easy-rsa」に移動しておきます。

# cd /etc/easy-rsa

認証局の構築をしていきます。
以下のコマンドで認証局の初期化を行います。

# easyrsa init-pki

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

完了したら、認証局の鍵ペアを生成します。

# easyrsa build-ca

Using SSL: opensslOpenSSL 1.1.1d  10 Sep 2019
　
Enter New CA Key Passphrase: ［任意のパスフレーズを入力］
Re-Enter New CA Key Passphrase: ［任意のパスフレーズを入力］
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]:［任意の名前を入力］
　
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

作成された認証局の証明書をVPNサーバーに移します。
証明書なのでまぁ適当に移せば良いかと思います。
下の例ではSCPを使用していますが…私はSFTPを使用しました。

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

VPN用の鍵の生成（VPNサーバー）

まずは、ファイルの移動も考えて、以下のコマンドでOpenVPNをインストールします。

# pacman -S openvpn

インストールが完了したら、認証局から受け取った証明書を適切な場所に移動させます。

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

VPNサーバー側にも「Easy-RSA」をインストールして、ディレクトリを移動します。

# pacman -S easy-rsa
# cd /etc/easy-rsa

認証局と同様に初期化します。

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

VPNサーバー

pacman -S openvpn

VPNサーバー設定ファイル

cp /usr/share/openvpn/examples/server.conf /etc/openvpn/server/server.conf

# nano /etc/openvpn/server/server.conf

ポート番号

port 1194

↓

port xxxx

プロトコル（基本udpだけど、proxy越えしたい場合はtcp）

;proto tcp
proto udp

↓

proto tcp
;proto udp

プロトコルをTCPにした場合は以下も…

explicit-exit-notify 1

↓

;explicit-exit-notify 1

認証局の公開鍵（変える必要ないはず）

ca ca.crt

↓

ca ca.crt

サーバーの公開鍵

cert server.crt

↓

cert servername.crt

サーバーの（署名された）秘密鍵

key server.key  # This file should be kept secret

↓

key servername.key  # This file should be kept secret

暗号通信用のパラメータファイル

dh dh2048.pem

↓

dh dh.pem

HMAC共通鍵（変えなくてもいいはず）

tls-auth ta.key 0

↓

tls-auth ta.key 0

プロセスのユーザーとグループ

;user nobody
;group nobody

↓

user nobody
group nobody

よくわからん！（変えなくてもいいはず）

cipher AES-256-CBC

↓

cipher AES-256-CBC

以下追記

auth SHA512
tls-version-min 1.2
tls-cipher TLS-DHE-RSA-WITH-AES-256-GCM-SHA384:TLS-DHE-RSA-WITH-AES-128-GCM-SHA256:TLS-DHE-RSA-WITH-AES-256-CBC-SHA:TLS-DHE-RSA-WITH-CAMELLIA-256-CBC-SHA:TLS-DHE-RSA-WITH-AES-128-CBC-SHA:TLS-DHE-RSA-WITH-CAMELLIA-128-CBC-SHA

サービス起動！

systemctl start openvpn-server@server

VPNクライアント設定ファイル

「ovpngen」のインストール

cd ~

wget https://github.com/graysky2/ovpngen/archive/v1.28.tar.gz

tar -xvf v1.28.tar.gz

cd ovpngen-1.28

chmod +x ovpngen

VPNクライアント用設定ファイルの生成

./ovpngen ［VPNサーバーのIPアドレスまたはURL］ /etc/openvpn/server/ca.crt /etc/easy-rsa/pki/signed/client1.crt /etc/easy-rsa/pki/private/client1.key /etc/openvpn/server/ta.key 1194 tcp > client.conf

このファイルをクライアントに持って行って接続？？？