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Question

Many interfaces when using VPN

Forum|Forum|1 year ago
September 24, 2024
37 replies
9521 views

Hello,

We have a problem with our VPN.

We are experiencing an issue that occurs once every month, where employees (it changes - skipping between users) using only Mac computers come to the office (but happens also in their home wifi) and are unable to access internet when they are connected to VPN.

We use:
Forticlient vpn only free - last version

IPSEC VPN

When they try to ping servers/addresses: sendto no buffer space available

When it happens I see many interfaces with addresses of VPN (192.168.11.0/24).
After disabling interface with VPN: ifconfig interface utun4 down - internet works!

Another user told me: WIFI works, VPN works. He leaves the computer, computer goes to sleep mode and after that Forticlient seems as connected but no internet!

Another user reported: I was on the train, using HOTSPOT and Forticlient.

Close the lid (So internet was disconnected). Went to the Office, I was connected to Office's WIFI and had this problem of buffering.

Why are there many interfaces instead of just one? Why does FortiClient create multiple connections?

#Same user#Same user#Same user#Another user

Thanks

AEK

SuperUser

Hi CaptainIT

If it is full tunnel then I guess the active default route is pointing to the wrong tunnel interface, and when you disable it then the default route points to the right interface.

And regarding the multiple interface creation, do you confirm that it creates one new interface each time you initiate a new VPN connection? Or does it create them all at once?

Can you also check if the below access rights are provided:

https://docs.fortinet.com/document/forticlient/7.4.0/macos-release-notes/223986/special-notices

AEK

captainitAuthor

New Member

Hello,
If it is full tunnel then I guess the active default route is pointing to the wrong tunnel interface, and when you disable it then the default route points to the right interface - what can I do please to fix it? I have full tunnel

And regarding the multiple interface creation, do you confirm that it creates one new interface each time you initiate a new VPN connection? Or does it create them all at once? It creates one when people using FortiClient normally without any problem and when they problem we see multiple interfaces.

Can you also check if the below access rights are provided - Checked - they have permission.

What can I do please in order to solve this problem ?

Thanks

AEK

SuperUser

Hi

Which MacOS version?

AEK

captainitAuthor

New Member

All the users with Somoma

AEK

SuperUser

Can you try an older FCT version like 7.0.13 or 7.2.5?

AEK

SuperUser

Anything relevant in FortiClient logs or in system event logs?

In FortiClient you can export the logs then try search around the time of the issue.

On MacOS I'm not sure but it should be in /var/log/system.log and with Console app (try to filter on network logs).

AEK

captainitAuthor

New Member

Attaching file of the logs from Forticlient:
The problem appears yersterday (In my clock time it is around 08:45-09:15 AM)

Thanks

AEK

SuperUser

By the way there is a known issue on 7.4.0 and some 7.2.x versions. This bug looks the same as yours but it affects ZTNA instead of IPsec.

1012318

Endpoints cannot connect to ZTNA after sleep or lid is off/on.

AEK

captainitAuthor

New Member

Hello,
I’m having trouble understanding an issue with the IPsec configuration in FortiClient VPN. We initially set the local ID in Phase 1 to a group using a full tunnel. Later, we changed it to a local ID with a split tunnel in the same client. However, after the computer wakes up from sleep mode, users seem to reconnect to the full tunnel. I can tell this because I’ve written a script that kills FortiClient if the public IP matches the office's public IP.
What can I do to resolve this issue?
Please help

AEK

SuperUser

Hi Captain

Can you share the routing table before and after wake up?

On the other hand did you manage to fix the initial issue?

AEK

captainitAuthor

New Member

We have reinstalled Forticlient for this user so now it is working again.
I don't know what to do, really...........

I just know that for sure he received the public IP of the office because I have script that if the public IP of internet is the same IP of office - kill Forticlient and it does.

captainitAuthor

New Member

This is my configuration for my IPSEC VPN in Fortigate,

Can I do something that may solve it?

AEK

SuperUser

Your screenshot shows only a little part that can't help. But I guess you enabled IPv4 split tunnel, right?

However I don't think the issue is from FG side since your client connects first with split tunnel successfully. So I think the issue is from client side.

Can you share the client's routing table before and after wake up? You can hide the public IP addresses before sharing.

AEK

captainitAuthor

New Member

Yes but it happens also for other users once a month.

I cannot share the routing table because now it works perfectly. So it will not refelect the real peoblem.

And also when doing ifconfig when it happens we can see 2 interface of utnu with the same segment of the VPN.

I really do not know what to do.

And as said - script of killng Forticlient is not helping.

Please help. It happens at least 3-4 times for different MACs computers.

Thanks

AEK

SuperUser

Hi Captain

I asked for the routing table but in your last message I think you said it works perfectly.

If there are some sensitive info that you can't share then you can blur them.

On the other hand, having a full tunnel after PC wake up may mean that a default route is being injected, while it shouldn't. We need confirmation from the output so we can move forward.

AEK

captainitAuthor

New Member

Hey,

Now we dont have a problem. Only one a month and I can't predict who will be the new one. Those people with the bugs are the same but most of the time they can work.

For example I dont have the problem now. Can I share with you my routing table before and after sleep even though I have never had this problem?

Thanks

AEK

SuperUser

The routing table must come from the affected node when you reproduce the error.

Once we understand well the issue you can for example make the right script to correct the issue.

AEK

captainitAuthor

New Member

I have Forticlient IPSEC - how can I know?

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