I'm running a small home network linux-based server which acts as an internet router, torrent client and file server. I have problems connecting Windows clients to server Samba shares ('user name or password is invalid'). How can I enable logging of all stages of Samba authentication/authorization procedure, such as "client connected", "client provided username ... and password ..." etc. so I can find out what exactly is wrong since I'm sure I'm providing proper username and password?
In cases of hanging, freezing, slow, unresponsive internet connections the cause is usually unreasonably identified as "MTU/MRU issue" with several hastily proposed "magic cures" (usually invalid or inapplicable for the situation) like commands involving iptables or ifconfig, and other "clamp MTU to TSS" spells.
What I want to know is what exactly the MTU/MRU issue is, why it affects the connection speed and latency, and how it is cured (known and modern methods), since I'd like to knowledgeably approach the resolution to the issue, not magically.