sources for configuration: # #


mode server

# bridged vpn with client IP range


# Protocol/port proto udp port 1194 ### Type of operation

# operation with PKI tls-server

# instead for using a symmetric key

secret /etc/openvpn/server_static.key

# for vpn with shared key

tls-auth xxx 1 # Device type dev tap0

# receive connection request on this local adress only
# if not defined, use all interfaces


# topology and network topology

# make IPs persistant
ifconfig-pool-persist ipp.txt

# clients can see each other

# see
sndbuf 393216
rcvbuf 393216

## PKI - certificates and keys, directory of cert/key
cd /etc/openvpn

## Root CA which signed openvpn server and client certs
ca /etc/easyrsa-pki/ca.crt
## cert of openvpn server
cert /etc/openvpn/locutus.netzwissen.local.crt

## key of server
key /etc/openvpn/locutus.netzwissen.local.key
# diffie hellman parameter
# create with: openssl genpkey -genparam -algorithm DH -out /etc/openvpn/dh2014.pem
dh /etc/easyrsa-pki/dh.pem

# certificate revocation list, should be copied from CA
crl-verify /etc/openvpn/crl.pem

# Verification of certs
# Details:
# old method (Name/name-prefix from CN field)
# verify-x509-name locutus.netzwissen.local name

# new method from RFC3280: type of certificate must be client
remote-cert-eku "TLS Web Client Authentication"

# Cipher algorithm
cipher AES-256-CBC
# HMAC Authentication
auth SHA256

# tunnel compression

# hardening. Beware: can exclude pre-2.3.3 clients
# tls-version-min 1.2

## pushed configs for clients for routing & dns
## redirect all traffic to VPN
## push "redirect-gateway def1" push "route"
push "dhcp-option DOMAIN netzwissen.local"
push "dhcp-option DNS"
push "dhcp-option WINS"

push "sndbuf 393216"
push "rcvbuf 393216"

# will not work with –ifconfig-pool-persist
# duplicate-cn # permissions after connect
user nobody
group nogroup

# dont re-read keys after –ping-restart

# dont restart tun after –ping-restart

log /var/log/openvpn.log

# Status info
status /var/log/openvpn-status.log 20

# dont repeat messages so often
mute 20

# Log-Levels: 0 no logging, 4 standard, 5 + 6 debugging, 9 max
verb 6

# Daemon-Mode: write to syslog - activate after the configuration finished

# Management console
management localhost 7505

Management Console

Die Management Konsole läuft auf localhost und ist über P. 7505 erreichbar.

root@server6:/etc/openvpn/staticclients# telnet localhost 7505

Beenden mit quit.

INFO:OpenVPN Management Interface Version 1 – type 'help' for more info help Management Interface for OpenVPN 2.3.10 x86_64-pc-linux-gnu [SSL (OpenSSL)] [LZO] [EPOLL] [PKCS11] [MH] [IPv6] built on Feb 2 2016 Commands: auth-retry t : Auth failure retry mode (none,interact,nointeract). bytecount n : Show bytes in/out, update every n secs (0=off). echo [on|off] [N|all] : Like log, but only show messages in echo buffer. exit|quit : Close management session. forget-passwords : Forget passwords entered so far. help : Print this message. hold [on|off|release] : Set/show hold flag to on/off state, or release current hold and start tunnel. kill cn : Kill the client instance(s) having common name cn. kill IP:port : Kill the client instance connecting from IP:port. load-stats : Show glsobal server load stats. log [on|off] [N|all] : Turn on/off realtime log display + show last N lines or 'all' for entire history. mute [n] : Set log mute level to n, or show level if n is absent. needok type action : Enter confirmation for NEED-OK request of 'type', where action = 'ok' or 'cancel'. needstr type action : Enter confirmation for NEED-STR request of 'type', where action is reply string. net : (Windows only) Show network info and routing table. password type p : Enter password p for a queried OpenVPN password. remote type [host port] : Override remote directive, type=ACCEPT|MOD|SKIP. proxy type [host port flags] : Enter dynamic proxy server info. pid : Show process ID of the current OpenVPN process. pkcs11-id-count : Get number of available PKCS#11 identities. pkcs11-id-get index : Get PKCS#11 identity at index. client-auth CID KID : Authenticate client-id/key-id CID/KID (MULTILINE) client-auth-nt CID KID : Authenticate client-id/key-id CID/KID client-deny CID KID R [CR] : Deny auth client-id/key-id CID/KID with log reason text R and optional client reason text CR client-kill CID [M] : Kill client instance CID with message M (def=RESTART) env-filter [level] : Set env-var filter level client-pf CID : Define packet filter for client CID (MULTILINE) rsa-sig : Enter an RSA signature in response to >RSA_SIGN challenge Enter signature base64 on subsequent lines followed by END signal s : Send signal s to daemon, s = SIGHUP|SIGTERM|SIGUSR1|SIGUSR2. state [on|off] [N|all] : Like log, but show state history. status [n] : Show current daemon status info using format #n. test n : Produce n lines of output for testing/debugging. username type u : Enter username u for a queried OpenVPN username. verb [n] : Set log verbosity level to n, or show if n is absent. version : Show current version number.

Debugging auf OpenVPN Client Seite (Linux)

journalctl -fu NetworkManager

Client IPs fest zuweisen

In die *.conf kommt eine neue Direktive:

client-config-dir /etc/openvpn/staticclients

In diesem Verzeichnis für jeden Client einen Datei openvpn_dvsdnet_[name] legen. Diese enthält die IP Adresse und die Netzmaske des Clients:


OpenVPN liest diese Datei beim Connect zusätzlich ein, aber DNS und Gateway kommen weiterhin über die zentralen push Kommandos. Ggf kann man auch ein Client-spezifisches Push anhängen, siehe dazu


EASYRSA: CA einrichten

./easyrsa init-pki ./easyrsa build-ca

DH erzeugen

./easyrsa gen-dh

EASYRSA: Zertifikate erzeugen

Signing Request (CSR) erzeugen, mit nopass = Key ohne Passwort

./easyrsa gen-req EntityName ./easyrsa gen-req EntityName nopass

danach signieren mit

./easyrsa sign-req server EntityName ./easyrsa sign-req client EntityName

server und client bestimmt, ob es ein Server oder Client Zertifikat ist.

Achtung bei OpenVPN: der Client sollte den im OpenVPN Zertifikat angegebenen Common Name prüfen. Server prüft seinerseits den Zertifikatstyp des Clients (RFC3280):

# Verification of certs # Details: # old method (Name/name-prefix from CN field) # verify-x509-name locutus.netzwissen.local name # new method from RFC3280: type of certificate must be client remote-cert-eku "TLS Web Client Authentication"

EASYRSA: Zertifikate zurückziehen

./easyrsa revoke server EntityName

Danach mit easyrsa gen-crl die zurückgezogenen zertifikate in die crl aufnehmen.

pki/index.txt zeigt, welche Zertifikate zurückkgezogen wurden.

Inhalte kontrollieren


openssl x509 -in pki/issued/openvpn.dvsdnet.local.crt -text -noout


openssl req -in -text -noout

  • openvpn.txt
  • Zuletzt geändert: 05/03/2024 - 10:52
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