I have configured an OpenVPN (2.2.1) server on an Ubuntu virtual machine in the Amazon elastic compute cloud. The server is up and running. I have installed OpenVPN (2.2.1) on a Mac OS X (10.8.2) client and I am using the openvpn2 binary to connect (in opposition to other clients like Tunnelblick or Viscosity). I can connect with the client and successfully ping or ssh the server through the tunnel.

However, I can't redirect all internet traffic through the VPN even if I use the push "redirect-gateway def1 bypass-dhcp" option in the server.conf configurations. When I connect to the server with these configurations, I get a successful connection, but then an infinite series of error messages: "write UDPv4: No route to host (code=65)". Traffic routing seems to be compromised because I am not able to access anything anymore, not even the OpenVPN server (by pinging 10.8.0.1 for instance).

This is beyond me. I am finding little help on the web and don't know what to try next. I don't think it is a problem of forwarding the traffic on the server since, first, I have also took care of that and, second, I can't even ping the VPN server locally through the tunnel (or ping anything at all for that matter).

Thank you for your help.

Here is the server.conf. file:

port 1194
proto udp
dev tun
ca ca.crt
cert ec2-server.crt
key ec2-server.key # This file should be kept secret
dh dh1024.pem
server 10.8.0.0 255.255.255.0
ifconfig-pool-persist ipp.txt
push "redirect-gateway def1 bypass-dhcp"
client-to-client
keepalive 10 120
comp-lzo
persist-key
persist-tun
status openvpn-status.log
verb 3

And the client.conf file:

client
dev tun
proto udp
remote servername.com 1194
resolv-retry infinite
nobind
persist-key
persist-tun
ca ca.crt
cert Toto5.crt
key Toto5.key
ns-cert-type server
comp-lzo
verb 3

Here is the connection log with the error messages:

$ sudo openvpn2 --config client.conf
Wed Mar 13 22:58:22 2013 OpenVPN 2.2.1 x86_64-apple-darwin12.2.0 [SSL] [LZO2] [eurephia] built on Mar 4 2013
Wed Mar 13 22:58:22 2013 NOTE: OpenVPN 2.1 requires '--script-security 2' or higher to call user-defined scripts or executables
Wed Mar 13 22:58:22 2013 LZO compression initialized
Wed Mar 13 22:58:22 2013 Control Channel MTU parms [ L:1542 D:138 EF:38 EB:0 ET:0 EL:0 ]
Wed Mar 13 22:58:22 2013 Socket Buffers: R=[196724->65536] S=[9216->65536]
Wed Mar 13 22:58:22 2013 Data Channel MTU parms [ L:1542 D:1450 EF:42 EB:135 ET:0 EL:0 AF:3/1 ]
Wed Mar 13 22:58:22 2013 Local Options hash (VER=V4): '41690919'
Wed Mar 13 22:58:22 2013 Expected Remote Options hash (VER=V4): '530fdded'
Wed Mar 13 22:58:22 2013 UDPv4 link local: [undef]
Wed Mar 13 22:58:22 2013 UDPv4 link remote: 54.234.43.171:1194
Wed Mar 13 22:58:22 2013 TLS: Initial packet from 54.234.43.171:1194, sid=ffbaf343 d0c1a266
Wed Mar 13 22:58:22 2013 VERIFY OK: depth=1, /C=US/ST=CA/L=SanFrancisco/O=Fort-Funst ... ost.domain
Wed Mar 13 22:58:22 2013 VERIFY OK: nsCertType=SERVER
Wed Mar 13 22:58:22 2013 VERIFY OK: depth=0, /C=US/ST=CA/L=SanFrancisco/O=Fort-Funst ... ost.domain
Wed Mar 13 22:58:23 2013 Data Channel Encrypt: Cipher 'BF-CBC' initialized with 128 bit key
Wed Mar 13 22:58:23 2013 Data Channel Encrypt: Using 160 bit message hash 'SHA1' for HMAC authentication
Wed Mar 13 22:58:23 2013 Data Channel Decrypt: Cipher 'BF-CBC' initialized with 128 bit key
Wed Mar 13 22:58:23 2013 Data Channel Decrypt: Using 160 bit message hash 'SHA1' for HMAC authentication
Wed Mar 13 22:58:23 2013 Control Channel: TLSv1, cipher TLSv1/SSLv3 DHE-RSA-AES256-SHA, 1024 bit RSA
Wed Mar 13 22:58:23 2013 [ec2-server] Peer Connection Initiated with 54.234.43.171:1194
Wed Mar 13 22:58:25 2013 SENT CONTROL [ec2-server]: 'PUSH_REQUEST' (status=1)
Wed Mar 13 22:58:25 2013 PUSH: Received control message: 'PUSH_REPLY,route 10.8.0.0 255.255.255.0,topology net30,ping 10,ping-restart 120,ifconfig 10.8.0.6 10.8.0.5'
Wed Mar 13 22:58:25 2013 OPTIONS IMPORT: timers and/or timeouts modified
Wed Mar 13 22:58:25 2013 OPTIONS IMPORT: --ifconfig/up options modified
Wed Mar 13 22:58:25 2013 OPTIONS IMPORT: route options modified
Wed Mar 13 22:58:25 2013 ROUTE default_gateway=0.0.0.0
Wed Mar 13 22:58:25 2013 TUN/TAP device /dev/tun0 opened
Wed Mar 13 22:58:25 2013 /sbin/ifconfig tun0 delete
ifconfig: ioctl (SIOCDIFADDR): Can't assign requested address
Wed Mar 13 22:58:25 2013 NOTE: Tried to delete pre-existing tun/tap instance -- No Problem if failure
Wed Mar 13 22:58:25 2013 /sbin/ifconfig tun0 10.8.0.6 10.8.0.5 mtu 1500 netmask 255.255.255.255 up
Wed Mar 13 22:58:25 2013 /sbin/route add -net 10.8.0.0 10.8.0.5 255.255.255.0
add net 10.8.0.0: gateway 10.8.0.5
Wed Mar 13 22:58:25 2013 Initialization Sequence Completed
^CWed Mar 13 22:58:30 2013 event_wait : Interrupted system call (code=4)
Wed Mar 13 22:58:30 2013 TCP/UDP: Closing socket
Wed Mar 13 22:58:30 2013 /sbin/route delete -net 10.8.0.0 10.8.0.5 255.255.255.0
delete net 10.8.0.0: gateway 10.8.0.5
Wed Mar 13 22:58:30 2013 Closing TUN/TAP interface
Wed Mar 13 22:58:30 2013 SIGINT[hard,] received, process exiting
toto5:ttntec2 Dominic$ sudo openvpn2 --config client.conf --remote ec2-54-234-43-171.compute-1.amazonaws.com
Wed Mar 13 22:58:57 2013 OpenVPN 2.2.1 x86_64-apple-darwin12.2.0 [SSL] [LZO2] [eurephia] built on Mar 4 2013
Wed Mar 13 22:58:57 2013 NOTE: OpenVPN 2.1 requires '--script-security 2' or higher to call user-defined scripts or executables
Wed Mar 13 22:58:57 2013 LZO compression initialized
Wed Mar 13 22:58:57 2013 Control Channel MTU parms [ L:1542 D:138 EF:38 EB:0 ET:0 EL:0 ]
Wed Mar 13 22:58:57 2013 Socket Buffers: R=[196724->65536] S=[9216->65536]
Wed Mar 13 22:58:57 2013 Data Channel MTU parms [ L:1542 D:1450 EF:42 EB:135 ET:0 EL:0 AF:3/1 ]
Wed Mar 13 22:58:57 2013 Local Options hash (VER=V4): '41690919'
Wed Mar 13 22:58:57 2013 Expected Remote Options hash (VER=V4): '530fdded'
Wed Mar 13 22:58:57 2013 UDPv4 link local: [undef]
Wed Mar 13 22:58:57 2013 UDPv4 link remote: 54.234.43.171:1194
Wed Mar 13 22:58:57 2013 TLS: Initial packet from 54.234.43.171:1194, sid=a0d75468 ec26de14
Wed Mar 13 22:58:58 2013 VERIFY OK: depth=1, /C=US/ST=CA/L=SanFrancisco/O=Fort-Funst ... ost.domain
Wed Mar 13 22:58:58 2013 VERIFY OK: nsCertType=SERVER
Wed Mar 13 22:58:58 2013 VERIFY OK: depth=0, /C=US/ST=CA/L=SanFrancisco/O=Fort-Funst ... ost.domain
Wed Mar 13 22:58:58 2013 Data Channel Encrypt: Cipher 'BF-CBC' initialized with 128 bit key
Wed Mar 13 22:58:58 2013 Data Channel Encrypt: Using 160 bit message hash 'SHA1' for HMAC authentication
Wed Mar 13 22:58:58 2013 Data Channel Decrypt: Cipher 'BF-CBC' initialized with 128 bit key
Wed Mar 13 22:58:58 2013 Data Channel Decrypt: Using 160 bit message hash 'SHA1' for HMAC authentication
Wed Mar 13 22:58:58 2013 Control Channel: TLSv1, cipher TLSv1/SSLv3 DHE-RSA-AES256-SHA, 1024 bit RSA
Wed Mar 13 22:58:58 2013 [ec2-server] Peer Connection Initiated with 54.234.43.171:1194
Wed Mar 13 22:59:00 2013 SENT CONTROL [ec2-server]: 'PUSH_REQUEST' (status=1)
Wed Mar 13 22:59:00 2013 PUSH: Received control message: 'PUSH_REPLY,redirect-gateway def1 bypass-dhcp,route 10.8.0.0 255.255.255.0,topology net30,ping 10,ping-restart 120,ifconfig 10.8.0.6 10.8.0.5'
Wed Mar 13 22:59:00 2013 OPTIONS IMPORT: timers and/or timeouts modified
Wed Mar 13 22:59:00 2013 OPTIONS IMPORT: --ifconfig/up options modified
Wed Mar 13 22:59:00 2013 OPTIONS IMPORT: route options modified
Wed Mar 13 22:59:00 2013 ROUTE default_gateway=0.0.0.0
Wed Mar 13 22:59:00 2013 TUN/TAP device /dev/tun0 opened
Wed Mar 13 22:59:00 2013 /sbin/ifconfig tun0 delete
ifconfig: ioctl (SIOCDIFADDR): Can't assign requested address
Wed Mar 13 22:59:00 2013 NOTE: Tried to delete pre-existing tun/tap instance -- No Problem if failure
Wed Mar 13 22:59:00 2013 /sbin/ifconfig tun0 10.8.0.6 10.8.0.5 mtu 1500 netmask 255.255.255.255 up
Wed Mar 13 22:59:00 2013 /sbin/route add -net 54.234.43.171 0.0.0.0 255.255.255.255
add net 54.234.43.171: gateway 0.0.0.0
Wed Mar 13 22:59:00 2013 /sbin/route add -net 0.0.0.0 10.8.0.5 128.0.0.0
add net 0.0.0.0: gateway 10.8.0.5
Wed Mar 13 22:59:00 2013 /sbin/route add -net 128.0.0.0 10.8.0.5 128.0.0.0
add net 128.0.0.0: gateway 10.8.0.5
Wed Mar 13 22:59:00 2013 /sbin/route add -net 10.8.0.0 10.8.0.5 255.255.255.0
add net 10.8.0.0: gateway 10.8.0.5
Wed Mar 13 22:59:00 2013 Initialization Sequence Completed
Wed Mar 13 22:59:00 2013 write UDPv4: No route to host (code=65)
Wed Mar 13 22:59:00 2013 write UDPv4: No route to host (code=65)
Wed Mar 13 22:59:01 2013 write UDPv4: No route to host (code=65)
Wed Mar 13 22:59:01 2013 write UDPv4: No route to host (code=65)
Wed Mar 13 22:59:01 2013 write UDPv4: No route to host (code=65)
Wed Mar 13 22:59:02 2013 write UDPv4: No route to host (code=65)
Wed Mar 13 22:59:02 2013 write UDPv4: No route to host (code=65)
Wed Mar 13 22:59:02 2013 write UDPv4: No route to host (code=65)
Wed Mar 13 22:59:02 2013 write UDPv4: No route to host (code=65)
Wed Mar 13 22:59:02 2013 write UDPv4: No route to host (code=65)
...

The routing table after a connection WITHOUT the push redirect-gateway (all traffic is not redirected to the VPN and everything is working fine, I can ping or ssh the OpenVPN server and access all other Internet resources through my default gateway):

Destination        Gateway            Flags        Refs      Use   Netif Expire
default            user148-1.wireless UGSc           50        0     en1
10.8/24            10.8.0.5           UGSc            2        7    tun0
10.8.0.5           10.8.0.6           UH              3        2    tun0
127                localhost          UCS             0        0     lo0
localhost          localhost          UH              6     6692     lo0
client.openvpn.net client.openvpn.net UH              3       18     lo0
142.1.148/22       link#5             UCS             2        0     en1
user148-1.wireless 0:90:b:27:10:71    UHLWIir        50        0     en1     76
user150-173.wirele localhost          UHS             0        0     lo0
142.1.151.255      ff:ff:ff:ff:ff:ff  UHLWbI          0        2     en1
169.254            link#5             UCS             1        0     en1
169.254.255.255    0:90:b:27:10:71    UHLSWi          0        0     en1     71

The routing table after a connection with the push redirect-gateway option enable as in the server.conf file above (all internet traffic should be redirected to the VPN tunnel, but nothing is working, I can't access any Internet ressources at all):

Destination        Gateway            Flags        Refs      Use   Netif Expire
0/1                10.8.0.5           UGSc            1        0    tun0
default            user148-1.wireless UGSc            7        0     en1
10.8/24            10.8.0.5           UGSc            0        0    tun0
10.8.0.5           10.8.0.6           UHr             6        0    tun0
54.234.43.171/32   0.0.0.0            UGSc            1        0     en1
127                localhost          UCS             0        0     lo0
localhost          localhost          UH              3     6698     lo0
client.openvpn.net client.openvpn.net UH              0       27     lo0
128.0/1            10.8.0.5           UGSc            2        0    tun0
142.1.148/22       link#5             UCS             1        0     en1
user148-1.wireless 0:90:b:27:10:71    UHLWIir         1        0     en1    833
user150-173.wirele localhost          UHS             0        0     lo0
169.254            link#5             UCS             1        0     en1
169.254.255.255    0:90:b:27:10:71    UHLSW           0        0     en1