Asterisk over OpenVPN-ask configuration

Hi all,

I have install OpenVPN server at the same box with Asterisk Server (Elastix)-I use IP public for VoIP server. and also have install openVPN client on my laptop.
I use Phonerlite as VoIP client (softphone on windows). I use for IP openvpn server and,,, … IP openvpn client. OpenVPN server and client can connect. I can ping openvpn server from client.

Integrate VOIP client with OpenVPN client, just fill openvpn client ip address on VoIP client proxy, in VoIP server, I configure /etc/asterisk/sip.conf - bindaddr= I register VoIP client, It is registered, but I check on cli - sip show peers, no one voip client registered.

so my question, any body here have experience with configuration asterisk server over openvpn?

thanks before


I use OpenVPN to connect remote offices as well as on my laptop with a soft client. My OpenVPN server is NOT my Asterisk server as yours is.

Once OpenVPN was running and I verified that routing between server and client was working, I was able to set a client to register with Asterisk as I would a client on the local LAN segment. I did not use any of the VPN addresses, just the IP addresses of the local subnet.

I did this some time ago. It worked, except for that the sound quality was rather bad. I don’t remember the details, but I believe that OpenVPN connection were set up as a TCP tunnel.

OpenVPN can set up as TCP tunneling or UDP tunneling, that depend on our configuration, if we want to use UDP tunneling, so in our configuration just mention on server.conf “proto udp-server” and in client config “proto udp-client”. for TCP tunneling, “proto tcp-server” in server and “proto tcp-client” in client.
but my problem now, VoIP client which use proxy openvpn client, cannot connect to my voip server which is also OpenVPN server. my scenario is

VoIP client ---- OpenVPN client ------------------------------ OpenVPN server — VoIP Server

I really need help, already 1 week I tried, but I cannot. in VoIP Client Debug, It is registered on the server, but I cannot make a call. and I check on VoIP server, VoIP Client is not registered. I think, something wrong with my configuration.

First the connectivity basics.
Assuming you are NOT using bridging…

The config line if both the server and client config files is ‘proto udp’, not ‘proto udp-server’ or ‘proto udp-client’

From the client, can you ping the server’s address as defined in the server.conf file?
From the client, can you ping the address you entered into the client softphone?
Can the server ping the client’s IP address?

On the server, what is the output of…

You stated that the client is Windows, what is the output of ipconfig as it relates to the tun interface?

Have you checked the server firewall rules so that they are not causing problems with the tun0 interface?

When starting the openVPN client on windows, did you start the GUI tool ‘as administrator’?

Thank you for you correction “proto udp”

FYI, my voip client and openvpn client is same machine. I use phonerlite as voip client.
I can ping openvpn server from client, but from server to client I cannot.

on my server,

tun0 Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 inet addr: P-t-P: Mask: UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:244 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:100 RX bytes:0 (0.0 b) TX bytes:20496 (20.0 KiB)
I use for my ip server, and for client and

this is my openvpn server configuration


Sample OpenVPN 2.0 config file for

multi-client server.

This file is for the server side

of a many-clients <-> one-server

OpenVPN configuration.

OpenVPN also supports

single-machine <-> single-machine

configurations (See the Examples page

on the web site for more info).

This config should work on Windows

or Linux/BSD systems. Remember on

Windows to quote pathnames and use

double backslashes, e.g.:

“C:\Program Files\OpenVPN\config\foo.key”

Comments are preceded with ‘#’ or ‘;’


Which local IP address should OpenVPN

listen on? (optional)

;local a.b.c.d

Which TCP/UDP port should OpenVPN listen on?

If you want to run multiple OpenVPN instances

on the same machine, use a different port

number for each one. You will need to

open up this port on your firewall.

port 1805

TCP or UDP server?

proto tcp
;proto udp

“dev tun” will create a routed IP tunnel,

“dev tap” will create an ethernet tunnel.

Use “dev tap0” if you are ethernet bridging

and have precreated a tap0 virtual interface

and bridged it with your ethernet interface.

If you want to control access policies

over the VPN, you must create firewall

rules for the the TUN/TAP interface.

On non-Windows systems, you can give

an explicit unit number, such as tun0.

On Windows, use “dev-node” for this.

On most systems, the VPN will not function

unless you partially or fully disable

the firewall for the TUN/TAP interface.

;dev tap
dev tun

Windows needs the TAP-Win32 adapter name

from the Network Connections panel if you

have more than one. On XP SP2 or higher,

you may need to selectively disable the

Windows firewall for the TAP adapter.

Non-Windows systems usually don’t need this.

;dev-node MyTap

SSL/TLS root certificate (ca), certificate

(cert), and private key (key). Each client

and the server must have their own cert and

key file. The server and all clients will

use the same ca file.

See the “easy-rsa” directory for a series

of scripts for generating RSA certificates

and private keys. Remember to use

a unique Common Name for the server

and each of the client certificates.

Any X509 key management system can be used.

OpenVPN can also use a PKCS #12 formatted key file

(see “pkcs12” directive in man page).

ca ca.crt
cert server.crt
key server.key # This file should be kept secret

Diffie hellman parameters.

Generate your own with:

openssl dhparam -out dh1024.pem 1024

Substitute 2048 for 1024 if you are using

2048 bit keys.

dh dh1024.pem

Configure server mode and supply a VPN subnet

for OpenVPN to draw client addresses from.

The server will take for itself,

the rest will be made available to clients.

Each client will be able to reach the server

on Comment this line out if you are

ethernet bridging. See the man page for more info.


Maintain a record of client <-> virtual IP address

associations in this file. If OpenVPN goes down or

is restarted, reconnecting clients can be assigned

the same virtual IP address from the pool that was

previously assigned.

ifconfig-pool-persist /etc/openvpn/ipp.txt

Configure server mode for ethernet bridging.

You must first use your OS’s bridging capability

to bridge the TAP interface with the ethernet

NIC interface. Then you must manually set the

IP/netmask on the bridge interface, here we

assume Finally we

must set aside an IP range in this subnet

(start= end= to allocate

to connecting clients. Leave this line commented

out unless you are ethernet bridging.


Configure server mode for ethernet bridging

using a DHCP-proxy, where clients talk

to the OpenVPN server-side DHCP server

to receive their IP address allocation

and DNS server addresses. You must first use

your OS’s bridging capability to bridge the TAP

interface with the ethernet NIC interface.

Note: this mode only works on clients (such as

Windows), where the client-side TAP adapter is

bound to a DHCP client.


Push routes to the client to allow it

to reach other private subnets behind

the server. Remember that these

private subnets will also need

to know to route the OpenVPN client

address pool (

back to the OpenVPN server.

;push “route”
;push “route”

To assign specific IP addresses to specific

clients or if a connecting client has a private

subnet behind it that should also have VPN access,

use the subdirectory “ccd” for client-specific

configuration files (see man page for more info).

EXAMPLE: Suppose the client

having the certificate common name “Thelonious”

also has a small subnet behind his connecting

machine, such as

First, uncomment out these lines:

;client-config-dir ccd
client-config-dir /etc/openvpn/ccd


Then create a file ccd/Thelonious with this line:


This will allow Thelonious’ private subnet to

access the VPN. This example will only work

if you are routing, not bridging, i.e. you are

using “dev tun” and “server” directives.

EXAMPLE: Suppose you want to give

Thelonious a fixed VPN IP address of

First uncomment out these lines:

;client-config-dir ccd

Then add this line to ccd/Thelonious:


Suppose that you want to enable different

firewall access policies for different groups

of clients. There are two methods:

(1) Run multiple OpenVPN daemons, one for each

group, and firewall the TUN/TAP interface

for each group/daemon appropriately.

(2) (Advanced) Create a script to dynamically

modify the firewall in response to access

from different clients. See man

page for more info on learn-address script.

;learn-address ./script

If enabled, this directive will configure

all clients to redirect their default

network gateway through the VPN, causing

all IP traffic such as web browsing and

and DNS lookups to go through the VPN

(The OpenVPN server machine may need to NAT

or bridge the TUN/TAP interface to the internet

in order for this to work properly).

;push “redirect-gateway def1 bypass-dhcp”

Certain Windows-specific network settings

can be pushed to clients, such as DNS

or WINS server addresses. CAVEAT:

The addresses below refer to the public

DNS servers provided by

;push “dhcp-option DNS”
;push “dhcp-option DNS”

Uncomment this directive to allow different

clients to be able to “see” each other.

By default, clients will only see the server.

To force clients to only see the server, you

will also need to appropriately firewall the

server’s TUN/TAP interface.


Uncomment this directive if multiple clients

might connect with the same certificate/key

files or common names. This is recommended

only for testing purposes. For production use,

each client should have its own certificate/key







The keepalive directive causes ping-like

messages to be sent back and forth over

the link so that each side knows when

the other side has gone down.

Ping every 10 seconds, assume that remote

peer is down if no ping received during

a 120 second time period.

keepalive 10 120

For extra security beyond that provided

by SSL/TLS, create an “HMAC firewall”

to help block DoS attacks and UDP port flooding.

Generate with:

openvpn --genkey --secret ta.key

The server and each client must have

a copy of this key.

The second parameter should be ‘0’

on the server and ‘1’ on the clients.

;tls-auth ta.key 0 # This file is secret

Select a cryptographic cipher.

This config item must be copied to

the client config file as well.

;cipher BF-CBC # Blowfish (default)
;cipher AES-128-CBC # AES
;cipher DES-EDE3-CBC # Triple-DES

Enable compression on the VPN link.

If you enable it here, you must also

enable it in the client config file.


The maximum number of concurrently connected

clients we want to allow.

max-clients 50

It’s a good idea to reduce the OpenVPN

daemon’s privileges after initialization.

You can uncomment this out on

non-Windows systems.

;user nobody
;group nobody

The persist options will try to avoid

accessing certain resources on restart

that may no longer be accessible because

of the privilege downgrade.


Output a short status file showing

current connections, truncated

and rewritten every minute.

status openvpn-status.log

By default, log messages will go to the syslog (or

on Windows, if running as a service, they will go to

the “\Program Files\OpenVPN\log” directory).

Use log or log-append to override this default.

“log” will truncate the log file on OpenVPN startup,

while “log-append” will append to it. Use one

or the other (but not both).

;log openvpn.log
;log-append openvpn.log

Set the appropriate level of log

file verbosity.

0 is silent, except for fatal errors

4 is reasonable for general usage

5 and 6 can help to debug connection problems

9 is extremely verbose

verb 3

Silence repeating messages. At most 20

sequential messages of the same message

category will be output to the log.

;mute 20[/code]
my question now, why I cannot ping openvpn client from server? should i add some comment on configuration?

Windows version? Is there a policy/firewall blocking pings?
You list 2 non-sequential IPs for your client, are there two clients with the same problem? I have found the P-t-P tunnel created uses two sequential IPs, like nad The .14 address would be pingable from the server, the .13 address is not.
Have you confirmed the TUN ip address(es) on Windows?

Thank to remain me about firewall on my windows, so when i open it, now I can ping client form server.
on OpenVpn, IP address will be use 4 ip address, lets say for client X.X.X.6-X.X.X.9, for 2nd client will be x.x.x.10-13. I dont know for what purpose. because of that i use for 1st client .14 and next .18.

and then my next question is, how to configure voip client and voip server can communicate through OpenVPN?
this is also good article to be reference

Many thank, now one problem solved (ping server to client and ping client to server).

I have never setup an Asterisk server on an openVPN server, but from experience of accessing other services on the openVPN server, I believe this should work.

Setup the end-point in Asterisk as you would any other local end point.

Turn on IP forwarding on the openVPN server.

NOTE: the above command turns it on now but it will be off again on system restart. To make it persistent, edit /etc/sysctl.conf and edit/add the line: net.ipv4.ip_forward = 1

On the Client, set the server ip to that of the Asterisk server’s ethX interface address, not the tun0 interface. (Since openVPN may not be started before Asterisk, Asterisk my not properly accept connections from the tun0 interface.)

Hi all,
need help…

now my openVPN(OVPN) client and OVPN server can communicate each other, I can ping from server to client and client to server.

now my problem is my VoIP Client (X-lite, phonerlite) can not register to VOIP Server (Asterisk 1.8.7). I try to capture problem with wireshark. from packet capture, I can see, voip client send request to voip server, but doesnt have sip respon from server. but on packet capture, there is ICMP for OVPN server to OVPN client which is message: 590 destination unreachable (Host administratively prohibited).

I have try and try to configure sip server also opvn server. but still have problem. any suggestion? any example configuration for sip.conf and server.conf (opvn) which is succeed?

thanks b4

Host Administratively Prohibited is the ICMP response for a firewalled port if using the Red Hat/CentOS firewall configuration tool. It means the firewall rules need to be adjusted to allow the sip packet through.

I have change firewall policy

#nano /etc/sysconfig/iptables #service network restart
and I also change port in sip.conf and server.conf
now my voip client connect to asterisk server.

and I make a call, it was ringging. but it doesnt have voice. and I try to analyze with wireshark on both voip client PC. there are rtp packet send, but only one way (just can capture sending packet).

Remember that SIP uses port 5060 for session control. The audio uses ports 10000 - 20000. The firewall has to account for those ports as well.

10000-20000 is the range in the sample configuration files. It is not the default range, from which you can infer it is not the only possible range.

The other side can choose its range independently.

Hi all,

Now I can connect my Asterisk server (Elastix) over OpenVPN. but delay in OpenVPN is higher. lets say, I try to capture call establishment delay, in normal connection (without security) - call establishment is lower than 60 ms, but over OpenVPN is higher than 200 ms. is there a way how to decrease delay?

Thank all for your help.