Halfway to openvpn

dgermann · 09-09-2008, 07:18 PM

Hi--

Trying to set up an openvpn connection between two Ubuntu 8.04.1 machines.

The server starts up fine and is running. But the client reports:

Code:

root@earth:~# openvpn /etc/openvpn/client.conf 
Tue Sep  9 20:10:04 2008 OpenVPN 2.1_rc7 i486-pc-linux-gnu [SSL] [LZO2] [EPOLL] built on Jun 11 2008
Tue Sep  9 20:10:04 2008 /usr/bin/openssl-vulnkey -q -b 1024 -m <modulus omitted>
Tue Sep  9 20:10:04 2008 Control Channel Authentication: using '/etc/openvpn/keys/ta.key' as a OpenVPN static key file
Tue Sep  9 20:10:04 2008 Outgoing Control Channel Authentication: Using 160 bit message hash 'SHA1' for HMAC authentication
Tue Sep  9 20:10:04 2008 Incoming Control Channel Authentication: Using 160 bit message hash 'SHA1' for HMAC authentication
Tue Sep  9 20:10:04 2008 LZO compression initialized
Tue Sep  9 20:10:04 2008 Control Channel MTU parms [ L:1558 D:166 EF:66 EB:0 ET:0 EL:0 ]
Tue Sep  9 20:10:04 2008 Data Channel MTU parms [ L:1558 D:1450 EF:58 EB:135 ET:0 EL:0 AF:3/1 ]
Tue Sep  9 20:10:04 2008 Local Options hash (VER=V4): '9e7066d2'
Tue Sep  9 20:10:04 2008 Expected Remote Options hash (VER=V4): '162b04de'
Tue Sep  9 20:10:04 2008 NOTE: UID/GID downgrade will be delayed because of --client, --pull, or --up-delay
Tue Sep  9 20:10:04 2008 Socket Buffers: R=[110592->131072] S=[110592->131072]
Tue Sep  9 20:10:04 2008 UDPv4 link local: [undef]
Tue Sep  9 20:10:04 2008 UDPv4 link remote: 10.66.77.1:1194
Tue Sep  9 20:10:04 2008 read UDPv4 [ECONNREFUSED]: Connection refused (code=111)
Tue Sep  9 20:10:06 2008 read UDPv4 [ECONNREFUSED]: Connection refused (code=111)
Tue Sep  9 20:10:08 2008 read UDPv4 [ECONNREFUSED]: Connection refused (code=111)

I am thinking it is something in my server.conf file that I haven't quite got right. Here's what that file looks like:

Code:

#################################################
# 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
local 192.168.0.2

# 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 1194

# 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 /etc/openvpn/keys/ca.crt
cert /etc/openvpn/keys/server.crt
key /etc/openvpn/keys/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 /etc/openvpn/keys/dh1024.pem

# Configure server mode and supply a VPN subnet
# for OpenVPN to draw client addresses from.
# The server will take 10.8.0.1 for itself,
# the rest will be made available to clients.
# Each client will be able to reach the server
# on 10.8.0.1. Comment this line out if you are
# ethernet bridging. See the man page for more info.
server 10.66.77.0 255.255.255.0

# 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 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 10.8.0.4/255.255.255.0.  Finally we
# must set aside an IP range in this subnet
# (start=10.8.0.50 end=10.8.0.100) to allocate
# to connecting clients.  Leave this line commented
# out unless you are ethernet bridging.
;server-bridge 10.8.0.4 255.255.255.0 10.8.0.50 10.8.0.100

# 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 (10.8.0.0/255.255.255.0)
# back to the OpenVPN server.
;push "route 192.168.10.0 255.255.255.0"
;push "route 192.168.20.0 255.255.255.0"
;push "route 192.168.0.0 255.255.255.0"
push "route 10.66.77.0 255.255.255.0"

# 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 192.168.40.128/255.255.255.248.
# First, uncomment out these lines:
;client-config-dir ccd
;route 192.168.40.128 255.255.255.248
# Then create a file ccd/Thelonious with this line:
#   iroute 192.168.40.128 255.255.255.248
# 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 10.9.0.1.
# First uncomment out these lines:
;client-config-dir ccd
;route 10.9.0.0 255.255.255.252
# Then add this line to ccd/Thelonious:
#   ifconfig-push 10.9.0.1 10.9.0.2

# 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
# the TUN/TAP interface to the internet in
# order for this to work properly).
# CAVEAT: May break client's network config if
# client's local DHCP server packets get routed
# through the tunnel.  Solution: make sure
# client's local DHCP server is reachable via
# a more specific route than the default route
# of 0.0.0.0/0.0.0.0.
;push "redirect-gateway"

# Certain Windows-specific network settings
# can be pushed to clients, such as DNS
# or WINS server addresses.  CAVEAT:
# http://openvpn.net/faq.html#dhcpcaveats
;push "dhcp-option DNS 10.8.0.1"
;push "dhcp-option WINS 10.8.0.1"

# 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.
client-to-client

# 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
# pair.
#
# IF YOU HAVE NOT GENERATED INDIVIDUAL
# CERTIFICATE/KEY PAIRS FOR EACH CLIENT,
# EACH HAVING ITS OWN UNIQUE "COMMON NAME",
# UNCOMMENT THIS LINE OUT.
;duplicate-cn

# 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
tls-auth /etc/openvpn/keys/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
cipher AES-256-CBC

# Enable compression on the VPN link.
# If you enable it here, you must also
# enable it in the client config file.
comp-lzo

# The maximum number of concurrently connected
# clients we want to allow.
max-clients 100

# 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.
persist-key
persist-tun

# 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  /var/log/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

So how can I get this working?

Thanks for your help!

billymayday · 09-09-2008, 07:29 PM

Is udp port 1194 open on the server?

Don't start the server as a daemon, run it from the command line an see what is going on at connection time.

dgermann · 09-09-2008, 07:51 PM

billymayday--

Thanks for jumping in to help. Good points.

Your second one first: I just ran

Code:

doug@doug2:/sam/doug2/dl-2008$ sudo openvpn /etc/openvpn/server.conf &

And the log file shows:

Code:

Tue Sep  9 20:45:09 2008 OpenVPN 2.1_rc7 i486-pc-linux-gnu [SSL] [LZO2] [EPOLL] 
built on Jun 11 2008
Tue Sep  9 20:45:09 2008 Diffie-Hellman initialized with 1024 bit key
Tue Sep  9 20:45:09 2008 /usr/bin/openssl-vulnkey -q -b 1024 -m <modulus omitted
>
Tue Sep  9 20:45:09 2008 Control Channel Authentication: using '/etc/openvpn/key
s/ta.key' as a OpenVPN static key file
Tue Sep  9 20:45:09 2008 Outgoing Control Channel Authentication: Using 160 bit message hash 'SHA1' for HMAC authentication
Tue Sep  9 20:45:09 2008 Incoming Control Channel Authentication: Using 160 bit message hash 'SHA1' for HMAC authentication
Tue Sep  9 20:45:09 2008 TLS-Auth MTU parms [ L:1558 D:166 EF:66 EB:0 ET:0 EL:0 ]
Tue Sep  9 20:45:09 2008 TUN/TAP device tun0 opened
Tue Sep  9 20:45:09 2008 TUN/TAP TX queue length set to 100
Tue Sep  9 20:45:09 2008 ifconfig tun0 10.66.77.1 pointopoint 10.66.77.2 mtu 1500
Tue Sep  9 20:45:09 2008 route add -net 10.66.77.0 netmask 255.255.255.0 gw 10.66.77.2
Tue Sep  9 20:45:09 2008 Data Channel MTU parms [ L:1558 D:1450 EF:58 EB:135 ET:0 EL:0 AF:3/1 ]
Tue Sep  9 20:45:09 2008 GID set to nobody
Tue Sep  9 20:45:09 2008 UID set to nobody
Tue Sep  9 20:45:09 2008 Socket Buffers: R=[110592->131072] S=[110592->131072]
Tue Sep  9 20:45:09 2008 UDPv4 link local (bound): 192.168.0.2:1194
Tue Sep  9 20:45:09 2008 UDPv4 link remote: [undef]
Tue Sep  9 20:45:09 2008 MULTI: multi_init called, r=256 v=256
Tue Sep  9 20:45:09 2008 IFCONFIG POOL: base=10.66.77.4 size=62
Tue Sep  9 20:45:09 2008 IFCONFIG POOL LIST
Tue Sep  9 20:45:09 2008 Initialization Sequence Completed

Now as to your first question, I do not know how to check if udp port 1194 is open. The fact you asked suggests that is not handled just in the server.conf file....

Thanks, billymayday!

dgermann · 09-09-2008, 08:06 PM

OK, maybe this is the answer:

Code:

doug@doug2:/sam/doug2/dl-2008$ sudo netstat -tulpn |grep 1194
udp        0      0 192.168.0.2:1194        0.0.0.0:*                           26110/openvpn

Looks to me like it is open. Am I reading that correctly?

Thanks!

Matir · 09-09-2008, 09:00 PM

It should be, unless it's firewalled. Is iptables running on the server? If so, you probably need to allow udp inbound to port 1194.

I just got done setting up an OpenVPN server for (slightly) more secure communications when away from home.

dgermann · 09-09-2008, 09:10 PM

Matir--

Thanks!

I don't think firewall is the problem. I have the same problem whether I have the firewall on or off. I generally use firestarter to set it up, but here is what I get with iptables --list (showing only the openvpn entries):

Code:

Chain INBOUND (1 references)
target     prot opt source               destination         

***

ACCEPT     tcp  --  192.168.0.0/24       anywhere            tcp dpt:openvpn 
ACCEPT     udp  --  192.168.0.0/24       anywhere            udp dpt:openvpn 
ACCEPT     tcp  --  10.66.77.0/24        anywhere            tcp dpt:openvpn 
ACCEPT     udp  --  10.66.77.0/24        anywhere            udp dpt:openvpn 
ACCEPT     tcp  --  10.66.77.0/24        anywhere            tcp dpt:openvpn 
ACCEPT     udp  --  10.66.77.0/24        anywhere            udp dpt:openvpn 

***

This is on the server side.

Is it possible that I have some things that don't make sense in the server.conf? I really did not understand what I was doing with the 10.66 addresses, nor with the 255.255 stuff. Perhaps I have that bolixed?

Thanks, Matir!

billymayday · 09-09-2008, 09:41 PM

For a start, when you run the server side, don't put the & at the end - you want to keep in running where you can see it.

Showing just openvpn stuff for iptables doesn't necessarily help - I had problems because I drop all private packets from my external NIC for example.

If you start the server, and try to connect from outside but see nothing, it's probably a firewall/prot forwarding type issue.

dgermann · 09-09-2008, 10:09 PM

billymayday--

Thanks!

Well, when I just run it from command line (without the &) I see nothing--no response. The only way I can see what it did is to open another terminal and check the log file.

Notice that I am not seeing nothing from the other side--what I am seeing is that [ECONNREFUSED] stuff. Does that answer your question about not seeing anything from the other side?

About the physical setup: Both computers are here in the same building, behind the same router, reaching each other through the same network switch. I want to get them seeing each other before I start trying to do this over the internet and two different cable providers.

I really don't think iptables are the issue. I have turned off the firewall in firestarter. Here is what I get when I check it out:

Code:

doug@doug2:~$ sudo iptables --list
Chain INPUT (policy ACCEPT)
target     prot opt source               destination         

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination

ON the client side, I still get:
Tue Sep 9 22:57:55 2008 read UDPv4 [ECONNREFUSED]: Connection refused (code=111)

So I am inclined to think the issue is elsewhere. Or am I missing something?

Thanks, billymayday!

billymayday · 09-09-2008, 10:21 PM

Are they on the same subnet - this probably won't work. I started this way, but suspicious of conflicts moved to an external route and life was much easier. I know my setup works, but I just tried it from this PC (on the same subnet) and it won't work - doesn't even register with the server.

Try from outside.

billymayday · 09-09-2008, 10:36 PM

Actually I lie - I did manage to get it to register at the server end.

If I start openvpn using

#openvpn server.conf

(where server.conf if my config file), I get some 100 lines of startup information. When I connect with a client, I see a reft of connection chatter. Are you really seeing nothing but the line you just typed? What does /var/log/openvpn.log tell you?

push "route 10.66.77.0 255.255.255.0"

Doen't look right to me - this should be your internal IP, so maybe 192.168.0.0 (based on your local IP)

dgermann · 09-10-2008, 10:03 AM

billymayday--

Many thanks for helping me. I feel like I am making some progress with your help.

Let me give back to you what I am reading, since I do not understand much about ipaddresses and networking:

1. I should try changing push "route 10.66.77.0 255.255.255.0" to "route 192.168.0.0 255.255.255.0"?

2. Next, if that does not work, I should change it back and try changing the subnet on the client side from 10.66.77 to something like 192.168.50. I am not sure if that is the proper meaning of subnet or if that refers to the 255.255.255.0 business....

3. Next, if that does not work, I should "try from outside" which I understand to mean lug the client box to somewhere where I can at least get a dialup and try it from there. Yes? That then means I need to open something on the router, too? It is a netgear wnr854t, if that makes a difference.

Yup, on the server side typing "openvpn /etc/openvpn/server.conf" and hitting <ret> results in nothing on screen. The openvpn.log in its entirety for one session is above in post # 3.

Thanks, billymayday!

billymayday · 09-10-2008, 03:22 PM

I don't get why things are so quiet on startup. Here's my output:

Quote:

]# openvpn server.conf
Thu Sep 11 06:18:29 2008 OpenVPN 2.1_rc2 x86_64-redhat-linux-gnu [SSL] [LZO2] [EPOLL] built on May 6 2007
Thu Sep 11 06:18:29 2008 Diffie-Hellman initialized with 1024 bit key
Thu Sep 11 06:18:29 2008 TLS-Auth MTU parms [ L:1541 D:138 EF:38 EB:0 ET:0 EL:0 ]
Thu Sep 11 06:18:29 2008 TUN/TAP device tun0 opened
Thu Sep 11 06:18:29 2008 TUN/TAP TX queue length set to 100
Thu Sep 11 06:18:29 2008 /sbin/ip link set dev tun0 up mtu 1500
Thu Sep 11 06:18:29 2008 /sbin/ip addr add dev tun0 local 10.8.0.1 peer 10.8.0.2
Thu Sep 11 06:18:29 2008 /sbin/ip route add 10.8.0.0/24 via 10.8.0.2
Thu Sep 11 06:18:29 2008 Data Channel MTU parms [ L:1541 D:1450 EF:41 EB:4 ET:0 EL:0 ]
Thu Sep 11 06:18:29 2008 GID set to nobody
Thu Sep 11 06:18:29 2008 UID set to nobody
Thu Sep 11 06:18:29 2008 Socket Buffers: R=[126976->131072] S=[126976->131072]
Thu Sep 11 06:18:29 2008 UDPv4 link local (bound): 192.168.0.2:1194
Thu Sep 11 06:18:29 2008 UDPv4 link remote: [undef]
Thu Sep 11 06:18:29 2008 MULTI: multi_init called, r=256 v=256
Thu Sep 11 06:18:29 2008 IFCONFIG POOL: base=10.8.0.4 size=62
Thu Sep 11 06:18:29 2008 IFCONFIG POOL LIST
Thu Sep 11 06:18:29 2008 [removed key name],10.8.0.4
Thu Sep 11 06:18:29 2008 [removed key name),10.8.0.8
Thu Sep 11 06:18:29 2008 Initialization Sequence Completed

And you see nothing?

I think the change in (1) is wha you need, but it won't stop the basic connection from happening, although getting it wrong may mean you can' do anything useful. I more mentioned it because I happened to see it there.

dgermann · 09-10-2008, 09:02 PM

billymayday--

OK, as I guessed, commenting out this line in server.conf gave me the full play-out of responses much like you see:

Code:

log-append  /var/log/openvpn.log

So I changed it back.

However, exchanging the commenting-out on these two did nothing to allow the client to connect--still getting the Connection refused error:

Code:

push "route 192.168.0.0 255.255.255.0"
;push "route 10.66.77.0 255.255.255.0"

So I put that back.

As to step 2, I see nothing in either conf file which allows me to set the subnet on the client side.

I may not be able to try step 3 for a week or more, so I did not do that.

What am I missing? How do my entries in the server.conf compare to yours?

Thanks for helping me, billymayday!

dgermann · 09-10-2008, 09:05 PM

Hi--

Also did some googling around. Most of the error code 111 postings I have seen have been in the server logs, not the client side.

One answer suggested using rdate, but I doubt that date is a problem since both client and server are set to get their times from the Internet, so I would not expect their clocks to be off more than a couple seconds. Running date on both computers confirms they are within a few seconds of each other.

billymayday · 09-10-2008, 10:50 PM

Humour me for a moment.

1. - you get "Tue Sep 9 20:10:04 2008 UDPv4 link remote: 10.66.77.1:1194" on the client side
2. - you have "local 192.168.0.2" on the server side.

Now if I connect locally (admittedly I'm connecting from WIndows), the IP in (1) is the server IP, but in (2) you are telling your server to listen on 192.168.0.2. What is you network layout?

Also, if you do an ifconfig, do you see something like

Code:

tun0      Link encap:UNSPEC  HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
          inet addr:10.8.0.1  P-t-P:10.8.0.2  Mask:255.255.255.255
          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

?