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draid
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Duplicate packet drop error - OpenVPN

Sat Feb 09, 2019 5:42 pm

Hello guys,

Long story short, I've used OpenVPN on a server behind the mikrotik but I had few problems so I've decided to setup OVPN server on the mikrotik (Hex). I've made the settings and everything seemed to be ok but when the client is connected to the server the mikrotik logs the following error:
duplicate packet, dropping
Also in the terminal pops up the following echo
17:22:38 echo: ovpn,debug,error,,,,,,,,,l2tp,info,,debug,,,critical,,,,,,,,,,,,,warning duplicate packet, dropp
ing

I've tried to reconfigure the server but the error keeps coming on every connection. However I'm able to connect to the server and everything seems to work. Do you have any idea where this error may come from?
 
draid
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Re: Duplicate packet drop error - OpenVPN

Sun Feb 10, 2019 1:19 pm

No one has any idea how to deal with this problem? I'm seriously stuck at this and the only thread I found with the same problem doesn't seems to deal with it.
 
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sebastia
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Re: Duplicate packet drop error - OpenVPN

Sun Feb 10, 2019 1:40 pm

Hi

Do you see it often? If not just ignore, it's informative, and Tik did the right thing already: dropped the duplicate.

It might be the consequence of tcp over tcp: opvn tunnel on Tik is tcp based, and if tcp connection is run through the tunnel, that might cause some (unnecessary) retransmissions.
 
kangarie
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Re: Duplicate packet drop error - OpenVPN

Sun Feb 10, 2019 1:41 pm

imho, just ignored it

i think, it's because your connection not stable
 
draid
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Re: Duplicate packet drop error - OpenVPN

Sun Feb 10, 2019 3:16 pm

Hi

Do you see it often? If not just ignore, it's informative, and Tik did the right thing already: dropped the duplicate.

It might be the consequence of tcp over tcp: opvn tunnel on Tik is tcp based, and if tcp connection is run through the tunnel, that might cause some (unnecessary) retransmissions.

Well to be hones I haven't tried to see if it will log the same error during some kind of transfer for example. For now it's logging it every time when a new connection is created to the server. I'd guess that it's logging it before the tunnel is up as it is at the beginning of the connection. The thing that bothers me most is that it echo in the terminal and I'm seeing there this long string which I've posted in the first comment.

Otherwise I'd say that it's pretty standard configuration - CA->Server->Client->vpn-pool->dhcp->ppp profile -> secret. Something strange that I've come to is that I don't have access to the router from the VPN client even when I have access to the server behind it. I'm yet to observe this problem but I was seriously disturbed by this dropping error.
 
inteq
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Re: Duplicate packet drop error - OpenVPN

Sun Feb 10, 2019 8:40 pm

Most people running ovpn on MT have this error. Nobody knows why or how to fix it. Only how to hide it in logs.
So your setup is OK.
I have it on all MT routers I am running or tested ovpn on.
Please stop responding if you have no input on the matter just to say "i think, it's because your connection not stable"
 
draid
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Re: Duplicate packet drop error - OpenVPN

Tue Feb 12, 2019 7:12 pm

Most people running ovpn on MT have this error. Nobody knows why or how to fix it. Only how to hide it in logs.
So your setup is OK.
I have it on all MT routers I am running or tested ovpn on.
Please stop responding if you have no input on the matter just to say "i think, it's because your connection not stable"
Thanks for the information. In this case I'll just search for a solution to hide the echo message in the terminal as it's really annoying. I could also consider l2tp/ipsec but for now I'd like to stick ot OVPN as the most secure way.
 
draid
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Re: Duplicate packet drop error - OpenVPN

Sat Feb 16, 2019 6:02 pm

Most people running ovpn on MT have this error. Nobody knows why or how to fix it. Only how to hide it in logs.
So your setup is OK.
I have it on all MT routers I am running or tested ovpn on.
Please stop responding if you have no input on the matter just to say "i think, it's because your connection not stable"
Could you please advice how to hide it at least at the terminal as I could not find a way to hide the echo (except disabling all critical echo) I officially surrendered to seek for options to solve the problem with the error (probably I could test it on another mikrotik device) I had even idea to write to mikrotik support but I'm not sure if they'll answer.

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