I’m attempting to setup OpenVPN on our server. The server is running Centos 7. After installing and configuring OpenVPN I can successfully connect from a Windows 10 client. But once connected I cannot access the internet. I also cannot ping the host server. Not related to OpenVPN, my server also uses KVM running multiple VM’s on a virtual network. I can also not ping the VM's when connected.
Host connection: 192.168.1.10
VPN network: 10.8.0.0
Virtual network: 10.8.8.0
I confirmed IP forwarding is enabled. I also updated Iptables with:
iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -o eth0 -j MASQUERADE
I listed below the OpenVPN server.conf and Ifconfig info.
I've been struggling with this for a week. At this point I'm stuck and not sure what to look at next. Any ideas?
OpenVPN server.conf:
port 1194
proto udp
dev tun
ca ca.crt
cert server.crt
key server.key # This file should be kept secret
dh dh2048.pem
ifconfig-pool-persist ipp.txt
server 10.8.0.0 255.255.255.0
push "route 192.168.1.10 255.255.255.255"
push "route 10.8.8.0 255.255.255.0"
push "redirect-gateway def1"
push "dhcp-option DNS 8.8.8.8"
push "dhcp-option DNS 8.8.4.4"
keepalive 10 120
user nobody
group nobody
persist-key
persist-tun
status openvpn-status.log
verb 3
client-to-client
explicit-exit-notify 1
Ifconfig:
eno1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.1.10 netmask 255.255.255.0 broadcast 192.168.1.255
inet6 fe80::3bcd:ddd4:4650:6087 prefixlen 64 scopeid 0x20<link>
ether ac:1f:6b:05:cc:96 txqueuelen 1000 (Ethernet)
RX packets 454678 bytes 136137391 (129.8 MiB)
RX errors 36 dropped 37074 overruns 0 frame 36
TX packets 213347 bytes 80743075 (77.0 MiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 1 (Local Loopback)
RX packets 91899 bytes 50703642 (48.3 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 91899 bytes 50703642 (48.3 MiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
tun0: flags=4305<UP,POINTOPOINT,RUNNING,NOARP,MULTICAST> mtu 1500
inet 10.8.0.1 netmask 255.255.255.255 destination 10.8.0.2
unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 txqueuelen 100 (UNSPEC)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
virbr1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 10.8.8.1 netmask 255.255.255.0 broadcast 10.8.8.255
ether 52:54:00:34:2a:4d txqueuelen 1000 (Ethernet)
RX packets 2663 bytes 193301 (188.7 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 2582 bytes 226983 (221.6 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
vnet0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet6 fe80::fc54:ff:fe6e:e2f prefixlen 64 scopeid 0x20<link>
ether fe:54:00:6e:0e:2f txqueuelen 1000 (Ethernet)
RX packets 2663 bytes 230583 (225.1 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 141674 bytes 7459999 (7.1 MiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
Update regarding accessing the VM's from a VPN connection:
When the libvirtd virtual bridge starts, iptables need to be modified to route VPN traffic to the VM's. Executing the following two firewall-cmd commands will manually insert the required rules. This will need to be done if firewall-cmd –reload, or any other command that restores firewalld rules, is executed.
Assumptions:
-
Virtual network device created for KVM is named virbr0 with subnet of 10.10.0.0/20 (adjust here and below as needed if virtual network was created under different device name).
-
OpenVPN device is named tun0 with subnet of 10.8.0.0/24
firewall-cmd --direct --passthrough ipv4 -I FORWARD 3 -d 10.10.0.0/20 -i tun0 -o virbr0 -j ACCEPT firewall-cmd --direct --passthrough ipv4 -I FORWARD 4 -s 10.10.0.0/20 -i virbr0 -o tun0 -j ACCEPT
Verify entries by executing iptables -t filter -S your should see the following amongst all the rules listed:
-A FORWARD -d 10.10.0.0/20 -i bridge0 -o virbr0 -j ACCEPT
-A FORWARD -s 10.10.0.0/20 -i virbr0 -o bridge0 -j ACCEPT
-A FORWARD -d 10.10.0.0/20 -i tun0 -o virbr0 -j ACCEPT
-A FORWARD -s 10.10.0.0/20 -i virbr0 -o tun0 -j ACCEPT
Note: The previous two firewall-cmd commands that were executed added the 3rd and 4th lines shown.
If needed, executing the following two firewall-cmd commands will manually remove the inserted rules.
firewall-cmd --direct --passthrough ipv4 -D FORWARD -d 10.10.0.0/20 -i tun0 -o virbr0 -j ACCEPT
firewall-cmd --direct --passthrough ipv4 -D FORWARD -s 10.10.0.0/20 -i virbr0 -o tun0 -j ACCEPT
Verify entries by executing iptables -t filter -S your should see the following amongst all the rules listed:
-A FORWARD -d 10.10.0.0/20 -i bridge0 -o virbr0 -j ACCEPT
-A FORWARD -s 10.10.0.0/20 -i virbr0 -o bridge0 -j ACCEPT
Note: The previous two firewall-cmd commands that were executed removed the 3rd and 4th lines that were shown above.
Issue: The libvirtd service will overwrite the rules added above on boot or restart. To get around this, add the following two libvirt scripts.
Script # 1: On start or reconnection of any VM associated with virbr0 (this will also execute on boot or by executing systemctl start libvirtd):
vi /etc/libvirt/hooks/qemu and insert the following:
#!/bin/bash
# Only execute this script if the opennebula-controller VM is started or reconnected
if [ "${1}" = "opennebula-controller=" ] ; then
# Check if vpn input routing rule exists. If not add it.
iptables -C FORWARD -d 10.10.0.0/20 -i tun0 -o virbr0 -j ACCEPT > /dev/null 2>&1
if [ $? = 1 ] ; then
if [ "${2}" = "started" ] || [ "${2}" = "reconnect" ]; then
firewall-cmd --direct --passthrough ipv4 -I FORWARD 3 -d 10.10.0.0/20 -i tun0 -o virbr0 -j ACCEPT
fi
fi
# Check if vpn output routing rule exists. If not add it.
iptables -C FORWARD -s 10.10.0.0/20 -i virbr0 -o tun0 -j ACCEPT > /dev/null 2>&1
if [ $? = 1 ] ; then
if [ "${2}" = "started" ] || [ "${2}" = "reconnect" ]; then
firewall-cmd --direct --passthrough ipv4 -I FORWARD 4 -s 10.10.0.0/20 -i virbr0 -o tun0 -j ACCEPT
fi
fi
fi
Write and close
Script # 2: On stop of the libvirtd daemon (this removes the rules so that on restart or by executing systemctl stop libvirtd, duplicate rules will not be inserted)
vi /etc/libvirt/hooks/daemon and insert the following:
#!/bin/bash
# Check if vpn input routing rule exists. If it does, remove it.
iptables -C FORWARD -d 10.10.0.0/20 -i tun0 -o virbr0 -j ACCEPT > /dev/null 2>&1
if [ $? = 0 ] ; then
if [ "${2}" = "shutdown" ]; then
firewall-cmd --direct --passthrough ipv4 -D FORWARD -d 10.10.0.0/20 -i tun0 -o virbr0 -j ACCEPT
fi
fi
# Check if vpn output routing rule exists. If it does, remove it.
iptables -C FORWARD -s 10.10.0.0/20 -i virbr0 -o tun0 -j ACCEPT > /dev/null 2>&1
if [ $? = 0 ] ; then
if [ "${2}" = "shutdown" ]; then
firewall-cmd --direct --passthrough ipv4 -D FORWARD -s 10.10.0.0/20 -i virbr0 -o tun0 -j ACCEPT
fi
fi
Write and close
Best Answer
I had LZO compression (comp-lzo) specified in my client configuration but not the server configuration. Once I corrected that issue I can now access the internet and the rest of the network.