Telnet server debug, connection [FIN] or [RST]

[legendbb]

a telnet server running on embedded system by inetd
telnet stream tcp nowait root telnetd telnetd -i

Continuously accessing this server by a client initiator, and do exact same loop.

After certain number of connect/disconnect, normally above 2000. There is a drop. But can reconnect right away, to get system going I can simply add a reconnect after connection dropped.

Wiresharked packets. The disconnect was actually initiated by server as [SYM/FIN] or [CON/RST], finish connection or connection reset, right after login no password echoed to client.

Don't know what actually caused such action or maybe it's an issue in telnetd doesn't like this kind of connect/disconnect.

Trying to find a way to debug this. Telnetd has a way to get log going, but not very obvious for me now. Will be trying telnetd debug mode soon.

Don't know how to debug such issue in TCP/IP layer.

Any idea / hint / comment are very very much appreciated.

[legendbb]

By test my client initiator to a Linux standard telnetd, connection/reconnection never breaks. So I draw conclusion, it's a limitation on the busybox/telnetd.

If have time, I will pull out the source and try to debug from there.