OpenVPN server 2.4.0 - 2.4.4 and dco-enabled client incompatibility
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- Dominant language
- C
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Description
I don't know if it belongs to here, but since I can reproduce the issue on OpenVPN GUI 2.6.6 and 2.6.0 but not 2.5.9, I thought it has something to do with the new driver.
My OpenVPN server is behind NAT, and has a topology roughly like this:
192.168.0.3 (client) <---> 103.116.76.243 (NAT border) <---> 10.111.213.190 (server)
The .pcap files indicates that client and server communication should be okay (and it works on OpenVPN GUI 2.5.9). Also I found the tun0 device on server has data flowed in and out. However, I can't find any data received on client dco device, through there are VPN packets in the ethernet capture file.
Here are the packets and log files on both sides (Hopefully no sensitive data). The client uses port 35663, udp protocol.
ovpn_issue.zip
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by inspecting the attached ovpn_issue.zip, especially the client and server logs and packet captures. Compare the behavior reported with OpenVPN GUI 2.5.9 against 2.6.0 and 2.6.6, focusing on traffic reaching tun0 but not the client DCO device. Done means identifying the incompatibility and documenting or implementing a reproducible resolution.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- c
- Domain
- networking, security
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Quiet
- Clarity
- Needs clarification
- Newbie friendliness
- 42/100