Some port filtered from client
I access via openvpn to my virtual server (proxmox) and I have a very special problem:
-Connected through the VPN I can access two Windows guest with RDP, if I nmap the machine the open port appears open. (work as expected)
-Connected through the VPN I cannot access the Linux guests with SSH, if I nmap the machine the open port appears filtered (even the port 80) but the guests answer to my ping requests.
-Connected through a ssh tunnel I can access everything, the open ports appears at open and everything works fine.
The guest are on the same network. I have some other install with the same settings and everything work well. We really do not understand.
Replying to myself, I found the solution thanks to this post: https://forum.pfsense.org/index.php?topic=88467.msg504596#msg504596
Go to "System->Advance Networking" and disable:
- Hardware Checksum Offloading
- Hardware TCP Segmentation Offloading
- Hardware Large Receive Offloading