VPN breaks connectivity between 2 NICs on 3 NIC machine
My current working setup is as follows:
Linux machine with 2 NICs (eth0 and wlan0) sitting behind a wireless router. Let's call this machine PC1.
connected to eth0 on PC1 is PC2 (Windows).
wireless router is 192.168.0.1 and wlan0 is 192.168.0.xxx.
eth0 is 10.42.0.1 and PC2 is at 10.42.0.xxx.
I have successfully used this setup to establish an OpenVPN connection (by right-clicking on a config file) from PC2 to an external server. That is, the connection goes through eth0 to the wireless router. Starting VPN creates on PC2 a virtual network adapter at 10.7.112.xxx with a gateway at 10.7.112.1.
So far, so good.
Problems started after I added eth1 to PC1. Its IP address is 192.168.1.1. Connected to it is PC3 at 192.168.1.xxx.
What kind of problems?
I can access PC2 from PC3 and the other way around unless I establish a VPN connection from PC2. After I do, PC2 and PC3 cannot see each other anymore unless I disconnect VPN, getting rid of the 10.7.112.xxx virtual adapter. Then, connectivity restores immediately.
I made sure, there's no active firewall rules.
The subnet masks on all of the above are 255.255.255.0. Does that matter?
What do I have to change to make the 3-NIC setup work as well as the 2-NIC one? Please do not suggest changing the layout - I need to understand what exactly is wrong with the current routing.
Thank you!
networking vpn
asked Jan 21 at 7:40
vanhemtvanhemt
112
add a comment |
My current working setup is as follows:
Linux machine with 2 NICs (eth0 and wlan0) sitting behind a wireless router. Let's call this machine PC1.
connected to eth0 on PC1 is PC2 (Windows).
wireless router is 192.168.0.1 and wlan0 is 192.168.0.xxx.
eth0 is 10.42.0.1 and PC2 is at 10.42.0.xxx.
I have successfully used this setup to establish an OpenVPN connection (by right-clicking on a config file) from PC2 to an external server. That is, the connection goes through eth0 to the wireless router. Starting VPN creates on PC2 a virtual network adapter at 10.7.112.xxx with a gateway at 10.7.112.1.
So far, so good.
Problems started after I added eth1 to PC1. Its IP address is 192.168.1.1. Connected to it is PC3 at 192.168.1.xxx.
What kind of problems?
I can access PC2 from PC3 and the other way around unless I establish a VPN connection from PC2. After I do, PC2 and PC3 cannot see each other anymore unless I disconnect VPN, getting rid of the 10.7.112.xxx virtual adapter. Then, connectivity restores immediately.
I made sure, there's no active firewall rules.
The subnet masks on all of the above are 255.255.255.0. Does that matter?
What do I have to change to make the 3-NIC setup work as well as the 2-NIC one? Please do not suggest changing the layout - I need to understand what exactly is wrong with the current routing.
Thank you!
networking vpn
asked Jan 21 at 7:40
vanhemtvanhemt
112
What VPN software are you using? What does PC2's routing table contain before and after establishing the VPN connection?
– grawity
Jan 21 at 8:08
No other software but the OpenVPN client. I use a config file from my VPN provider to connect and then just Ctrl+C to disconnect. I have the routing table pre and post - VPN. Which entries should I provide?
– vanhemt
Jan 21 at 12:55
@grawity: by 'OpenVPN client', I mean the Private Tunnel downloaded from openvpn.net. Works in terminal mode.
– vanhemt
Jan 21 at 12:58
@grawity: Okay, I can see that Default Gateway changes after starting VPN from 10.42.0.1 to 10.7.112.1 - could that be a problem?
– vanhemt
Jan 21 at 13:04
add a comment |
My current working setup is as follows:
Linux machine with 2 NICs (eth0 and wlan0) sitting behind a wireless router. Let's call this machine PC1.
connected to eth0 on PC1 is PC2 (Windows).
wireless router is 192.168.0.1 and wlan0 is 192.168.0.xxx.
eth0 is 10.42.0.1 and PC2 is at 10.42.0.xxx.
I have successfully used this setup to establish an OpenVPN connection (by right-clicking on a config file) from PC2 to an external server. That is, the connection goes through eth0 to the wireless router. Starting VPN creates on PC2 a virtual network adapter at 10.7.112.xxx with a gateway at 10.7.112.1.
So far, so good.
Problems started after I added eth1 to PC1. Its IP address is 192.168.1.1. Connected to it is PC3 at 192.168.1.xxx.
What kind of problems?
I can access PC2 from PC3 and the other way around unless I establish a VPN connection from PC2. After I do, PC2 and PC3 cannot see each other anymore unless I disconnect VPN, getting rid of the 10.7.112.xxx virtual adapter. Then, connectivity restores immediately.
I made sure, there's no active firewall rules.
The subnet masks on all of the above are 255.255.255.0. Does that matter?
What do I have to change to make the 3-NIC setup work as well as the 2-NIC one? Please do not suggest changing the layout - I need to understand what exactly is wrong with the current routing.
Thank you!
networking vpn
asked Jan 21 at 7:40
vanhemtvanhemt
112
My current working setup is as follows:
Linux machine with 2 NICs (eth0 and wlan0) sitting behind a wireless router. Let's call this machine PC1.
connected to eth0 on PC1 is PC2 (Windows).
wireless router is 192.168.0.1 and wlan0 is 192.168.0.xxx.
eth0 is 10.42.0.1 and PC2 is at 10.42.0.xxx.
I have successfully used this setup to establish an OpenVPN connection (by right-clicking on a config file) from PC2 to an external server. That is, the connection goes through eth0 to the wireless router. Starting VPN creates on PC2 a virtual network adapter at 10.7.112.xxx with a gateway at 10.7.112.1.
So far, so good.
Problems started after I added eth1 to PC1. Its IP address is 192.168.1.1. Connected to it is PC3 at 192.168.1.xxx.
What kind of problems?
I can access PC2 from PC3 and the other way around unless I establish a VPN connection from PC2. After I do, PC2 and PC3 cannot see each other anymore unless I disconnect VPN, getting rid of the 10.7.112.xxx virtual adapter. Then, connectivity restores immediately.
I made sure, there's no active firewall rules.
The subnet masks on all of the above are 255.255.255.0. Does that matter?
What do I have to change to make the 3-NIC setup work as well as the 2-NIC one? Please do not suggest changing the layout - I need to understand what exactly is wrong with the current routing.
Thank you!
networking vpn
networking vpn
asked Jan 21 at 7:40
vanhemtvanhemt
112
asked Jan 21 at 7:40
vanhemtvanhemt
112
asked Jan 21 at 7:40
vanhemtvanhemt
112
asked Jan 21 at 7:40
vanhemtvanhemt
112
asked Jan 21 at 7:40
vanhemtvanhemt
112
112
What VPN software are you using? What does PC2's routing table contain before and after establishing the VPN connection?
– grawity
Jan 21 at 8:08
No other software but the OpenVPN client. I use a config file from my VPN provider to connect and then just Ctrl+C to disconnect. I have the routing table pre and post - VPN. Which entries should I provide?
– vanhemt
Jan 21 at 12:55
@grawity: by 'OpenVPN client', I mean the Private Tunnel downloaded from openvpn.net. Works in terminal mode.
– vanhemt
Jan 21 at 12:58
@grawity: Okay, I can see that Default Gateway changes after starting VPN from 10.42.0.1 to 10.7.112.1 - could that be a problem?
– vanhemt
Jan 21 at 13:04
add a comment |
What VPN software are you using? What does PC2's routing table contain before and after establishing the VPN connection?
– grawity
Jan 21 at 8:08
No other software but the OpenVPN client. I use a config file from my VPN provider to connect and then just Ctrl+C to disconnect. I have the routing table pre and post - VPN. Which entries should I provide?
– vanhemt
Jan 21 at 12:55
@grawity: by 'OpenVPN client', I mean the Private Tunnel downloaded from openvpn.net. Works in terminal mode.
– vanhemt
Jan 21 at 12:58
@grawity: Okay, I can see that Default Gateway changes after starting VPN from 10.42.0.1 to 10.7.112.1 - could that be a problem?
– vanhemt
Jan 21 at 13:04
What VPN software are you using? What does PC2's routing table contain before and after establishing the VPN connection?
– grawity
Jan 21 at 8:08
What VPN software are you using? What does PC2's routing table contain before and after establishing the VPN connection?
– grawity
Jan 21 at 8:08
No other software but the OpenVPN client. I use a config file from my VPN provider to connect and then just Ctrl+C to disconnect. I have the routing table pre and post - VPN. Which entries should I provide?
– vanhemt
Jan 21 at 12:55
No other software but the OpenVPN client. I use a config file from my VPN provider to connect and then just Ctrl+C to disconnect. I have the routing table pre and post - VPN. Which entries should I provide?
– vanhemt
Jan 21 at 12:55
@grawity: by 'OpenVPN client', I mean the Private Tunnel downloaded from openvpn.net. Works in terminal mode.
– vanhemt
Jan 21 at 12:58
@grawity: by 'OpenVPN client', I mean the Private Tunnel downloaded from openvpn.net. Works in terminal mode.
– vanhemt
Jan 21 at 12:58
@grawity: Okay, I can see that Default Gateway changes after starting VPN from 10.42.0.1 to 10.7.112.1 - could that be a problem?
– vanhemt
Jan 21 at 13:04
@grawity: Okay, I can see that Default Gateway changes after starting VPN from 10.42.0.1 to 10.7.112.1 - could that be a problem?
– vanhemt
Jan 21 at 13:04
add a comment |
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What VPN software are you using? What does PC2's routing table contain before and after establishing the VPN connection?
– grawity
Jan 21 at 8:08
No other software but the OpenVPN client. I use a config file from my VPN provider to connect and then just Ctrl+C to disconnect. I have the routing table pre and post - VPN. Which entries should I provide?
– vanhemt
Jan 21 at 12:55
@grawity: by 'OpenVPN client', I mean the Private Tunnel downloaded from openvpn.net. Works in terminal mode.
– vanhemt
Jan 21 at 12:58
@grawity: Okay, I can see that Default Gateway changes after starting VPN from 10.42.0.1 to 10.7.112.1 - could that be a problem?
– vanhemt
Jan 21 at 13:04