I have run into this issue several times over the years:
- a Linux server is not configured for VLAN tagging
- It is connected to a switch that has 802.1q VLAN tagging on traffic going into the server.
The result is basically one-way comms where traffic from the server is able to go to the destination without issue, but packets coming to the server are dropped (but are seen on the interface). I normally have to take a tcpdump, scp it to GUI machine, launch Wireshark and then remember to look for the 802.1q header.
Is there any quicker/easier way to figure out this issue?