L2TP connection OK but can't transfer files

Post your questions about SoftEther VPN software here. Please answer questions if you can afford.
Post Reply
dandan
Posts: 7
Joined: Sat Oct 29, 2016 9:33 pm

L2TP connection OK but can't transfer files

Post by dandan » Sun Oct 30, 2016 1:30 pm

that's it.
I can access remote LAN IPs and browse shared folders successfully.

As soon as I transfer a file from the server to the client, ping reports timeout, the copy stalls at 0% and I have to wait almost a minute for Windows Explorer copy error message.
After those timeouts, the connection is running normally.

Tried connecting also with Windows native client but couldn't copy the file anyway.

I reconfigured the Server to use SoftEther protocol instead of L2TP but with the same results.

Used HTTP File Server utility to transfer files via HTTP instead of SMB, browser transfer stalls at 0% again.

Server version is v4.2 Build 9608 running on Windows 8.1 x64
Client version is v4.2 Build 9608 running on Windows 10 x64

I also tried with other client PC running Windows 7 x64, same results.

What am I doing wrong?

moatazelmasry
Posts: 336
Joined: Sat Aug 15, 2015 7:41 pm

Re: L2TP connection OK but can't transfer files

Post by moatazelmasry » Sun Oct 30, 2016 6:26 pm

It might be worth taking a look into the packet_log files on the server and see what is happening.

Out of curiosity. Are both the server and the client ipv4??

dandan
Posts: 7
Joined: Sat Oct 29, 2016 9:33 pm

Re: L2TP connection OK but can't transfer files

Post by dandan » Sun Oct 30, 2016 10:09 pm

Yes, both IPv4.

When running normally, the logfile looks like this:
SYN
SYN+ACK
SYN+ACK
FIN+ACK
FIN+ACK
SYN

Then, when I start the copy, the log changes to this:
RST+ACK
RST
SYN
SYN+ACK
RST+ACK
RST
SYN
SYN+ACK
RST+ACK
RST
SYN
SYN+ACK

I saw that everytime a RST occurs, WindowSize=0 and when there is a SYN or SYN+ACK the WindowSize=8192
Don't know if this is relevant...

moatazelmasry
Posts: 336
Joined: Sat Aug 15, 2015 7:41 pm

Re: L2TP connection OK but can't transfer files

Post by moatazelmasry » Mon Oct 31, 2016 8:02 pm

Hmm ok.

Are you using secureNAT. In this case what is the current mtu value? If it is very high, Can you set it to 1500 or 1497?

Also could you please post your current SoftEther config file

Regards,
Moataz

dandan
Posts: 7
Joined: Sat Oct 29, 2016 9:33 pm

Re: L2TP connection OK but can't transfer files

Post by dandan » Mon Oct 31, 2016 10:57 pm

I'm not using SecureNAT.

Please take a look at the attached config file, I edited the private bits.
You do not have the required permissions to view the files attached to this post.

moatazelmasry
Posts: 336
Joined: Sat Aug 15, 2015 7:41 pm

Re: L2TP connection OK but can't transfer files

Post by moatazelmasry » Tue Nov 01, 2016 11:29 am

On the first look I can't see anything unusual.

Which protocol are you using for file transfer? ftp?

Are you staring SoftEther using "execsvc" (I assume) or "start"?

What happens if you switch to SecureNAT instead of bridge?

dandan
Posts: 7
Joined: Sat Oct 29, 2016 9:33 pm

Re: L2TP connection OK but can't transfer files

Post by dandan » Tue Nov 01, 2016 5:35 pm

Thank you.

The protocols used where normal Windows SMB, HTTP (using rejetto.com/hfs) and also ftp. the problem occurs everytime.

I was able to copy only a small file like 200/300 kb, if the file is bigger the copy fails.

SoftEther Server starts automatically with Windows.

By your suggestion, I also tried SecureNAT (with disabled Virtual DHCP to avoid conflict) and the result was the same.


Did other test, I made some queries to a SQL Server and got the connection timeout like when I copy files.
Maybe this release is broken?

moatazelmasry
Posts: 336
Joined: Sat Aug 15, 2015 7:41 pm

Re: L2TP connection OK but can't transfer files

Post by moatazelmasry » Tue Nov 01, 2016 7:28 pm

Ok. I suspect this might be the mtu value somewhere.

To really make sure that of this theory, create a text file with 1 character in it and try to copy it over the network. If this works, this will tell us that the window size/mtu value somewhere is set too high, that the other side can not cope with.

And one more test, connect to the SoftEther server using OpenVPN and UDP (not TCP) and try to copy a small and large file.

dandan
Posts: 7
Joined: Sat Oct 29, 2016 9:33 pm

Re: L2TP connection OK but can't transfer files

Post by dandan » Tue Nov 01, 2016 10:07 pm

MTU=1500 on client and server NIC

moatazelmasry
Posts: 336
Joined: Sat Aug 15, 2015 7:41 pm

Re: L2TP connection OK but can't transfer files

Post by moatazelmasry » Tue Nov 01, 2016 10:36 pm

What about the other 2 questions?

- transfer a 1 byte file
- Use OpenVPN UDP

dandan
Posts: 7
Joined: Sat Oct 29, 2016 9:33 pm

Re: L2TP connection OK but can't transfer files

Post by dandan » Wed Nov 02, 2016 8:36 am

1 byte file is OK, 200/300 kb file is OK too but 400kb file it always fails.

Didn't have the chance to test OpenVPN yet but I'm using L2TP which is UDP also.

thisjun
Posts: 2458
Joined: Mon Feb 24, 2014 11:03 am

Re: L2TP connection OK but can't transfer files

Post by thisjun » Thu Nov 17, 2016 7:32 am

If you copy 400 kb file, it also failed copy at 0%?

dandan
Posts: 7
Joined: Sat Oct 29, 2016 9:33 pm

Re: L2TP connection OK but can't transfer files

Post by dandan » Sun Nov 20, 2016 11:58 am

yes, copy fails at 0%. I can only copy smaller files.
Like I previously said, I tested some queries to a SQL Server and also got the connection timeout like when I copy files, so I think the problem isn't related with the copy process, maybe high usage or something.

thisjun
Posts: 2458
Joined: Mon Feb 24, 2014 11:03 am

Re: L2TP connection OK but can't transfer files

Post by thisjun » Wed Dec 07, 2016 7:21 am

Umm....
Could you capture packets on virtual NIC by wireshark?

snarfsmojo
Posts: 2
Joined: Wed Jun 28, 2017 2:23 pm

Re: L2TP connection OK but can't transfer files

Post by snarfsmojo » Wed Jun 28, 2017 2:34 pm

dandan - did you ever get this resolved? I am having a VERY similar issue.

Post Reply