Re: USB-serial adapter suggestions needed

On Jan 11, 2024, at 12:12, bob prohaska <fbsd@www.zefox.net> wrote:

> On Wed, Jan 10, 2024 at 09:34:00PM -0800, Mark Millard wrote:
>> 
>> "&" creates background processes that are still killed when
>> their parent tty or controlling process goes away. nohup
>> avoids that kill.
> 
> Not sure what's going on, but if I use 
> make buildworld &
> on one of my RPi* hosts and log out or otherwise drop
> the connection, the job keeps going. Maybe use of tcsh?
> 
>> 
>> What was running on nemesis.zefox.com was its side of the
>> ssh that in turn was attached to the shell that in turn
>> was running tip --until those exited/were-killed on
>> nemesis.zefox.com .
>> 
>> But there is no information here about which of those was the
>> one to start the failure on nemesis.zefox.com :
>> 
>> A) Was it the tip process?
>> B) Was it the shell process?
>> C) Was it the nemesis.zefox.com side of the ssh?
>> 
> 
> 
> I've put relevant excerpts from /var/log/messages from
> ns2.zefox.net (the console host) and nemesis.zefox.com
> (the terminal server) at
> http://www.zefox.net/~fbsd/tiptrouble/
> They've been trimmed to the tip failure timeframe.

Note the "ucom_close" and "ucom_shutdown" and "ucom_cfg_close"
in:

Jan 10 14:12:54 nemesis syslogd: last message repeated 1 times
Jan 10 14:16:35 nemesis kernel: ucom_outwakeup: sc = 0xffffa00002466088
Jan 10 14:16:35 nemesis kernel: ucom_get_data: cnt=1
Jan 10 14:16:35 nemesis kernel: ucom_get_data: cnt=0
Jan 10 14:16:35 nemesis kernel: ucom_inwakeup: tp=0xffffa00001979800
Jan 10 14:16:35 nemesis syslogd: last message repeated 1 times
Jan 10 14:26:40 nemesis syslogd: last message repeated 1 times
Jan 10 14:29:48 nemesis syslogd: last message repeated 3 times
Jan 10 14:29:48 nemesis kernel: ucom_close: tp=0xffffa00001979800
Jan 10 14:29:48 nemesis kernel: ucom_shutdown: 
Jan 10 14:29:48 nemesis kernel: ucom_dtr: onoff = 0
Jan 10 14:29:48 nemesis kernel: ucom_line_state: on=0x00, off=0x01
Jan 10 14:29:48 nemesis kernel: ucom_rts: onoff = 1
Jan 10 14:29:48 nemesis kernel: ucom_line_state: on=0x02, off=0x00
Jan 10 14:29:48 nemesis kernel: ucom_cfg_close: 
Jan 10 15:04:07 nemesis su[35181]: bob to root on /dev/pts/4

Note the time frame vs. your reported:

QUOTE
Jan 10 13:14:06 ns2 sshd[48381]: fatal: Timeout before authentication for 59.56.110.106 port 50300
Jan 10 13:34:34 ns2 sshd[926]: error: beginning MaxStartups throttling
Jan 10 14:12:41 ns2 sshd[48506]: error: PAM: Authentication error for illegal user shutdown from 185.11.61.234


FreeBSD/arm (ns2.zefox.net) (ttyu0)

login: client_loop: send disconnect: Broken pipe
bob@raspberrypi:~ $ 
END QUOTE

Looks to me like something lead to ucom stopping on
nemesis.zefox.com .

The ns2.zefox.net shows:

QUOTE
Jan 10 14:12:41 ns2 sshd[48506]: error: PAM: Authentication error for illegal user shutdown from 185.11.61.234
Jan 10 14:26:28 ns2 sshd[48524]: error: Fssh_kex_exchange_identification: Connection closed by remote host
Jan 10 14:43:28 ns2 sshd[48546]: error: PAM: Authentication error for illegal user test from 85.209.11.226
Jan 10 15:14:29 ns2 sshd[48603]: error: kex protocol error: type 20 seq 2 [preauth]
Jan 10 15:14:29 ns2 sshd[48603]: error: kex protocol error: type 30 seq 3 [preauth]
END QUOTE

It does not suggest ns2.zefox.net as starting the sequence.


> There is a link to a copy of nemesis's sshd_debug.log file at
> http://nemesis.zefox.com/~bob/fbsd/sshd_debug.log
> The file seems too big to search interactively via a
> browser, but it might be possible to download it in
> one pass and then grep locally. For some reason it
> isn't timestamped in any way I recognize. 
> 
>> We only know that the end result was lack of anything
>> reading the pipe on nemesis.zefox.com : by then
>> the ssh side on nemesis.zefox.com had stopped being
>> set up to read the pipe.
>> 
>> 
>> Did you look at /var/logs/messages [or the analogous linux
>> place(s)] on "pi4 RasPiOS workstation"?  What, if anything, did
>> such have from around the failure time frame?
>> 
>> 
> I tried, but the naming is very different from FreeBSD and I
> didn't recognize any obvious candidates. I'll look more later.

Looking around I found in:

https://askubuntu.com/questions/26237/difference-between-var-log-messages-var-log-syslog-and-var-log-kern-log

QUOTE
2020 update

You may still stumble upon syslog; but the defaults have changed.
journald has replaced syslog, in quite a big portion of systems, including Ubuntu.

This is relevant because you won't be finding /var/log/messages that often anymore. journald doesn't write plaintext logs — it uses its own, compressed and partially authenticated format.

Search online for e.g. journalctl cheatsheet, or just study man 8 systemd-journald, man 1 journalctl yourself.

Syslog and journald are, to a degree, cross-compatible; you can transport logs between them in either direction. However, you won't get plaintext logs a-la /var/log/messages with journald; and you won't get structured (journalctl -o json-pretty) and authenticated logging with syslog.
END QUOTE

> Meanwhile, the non-ssh-mediated tip session from 
> nemesis.zefox.com to ns2.zefox.net's console gpio pins
> remains up.
> 

Looks like the 110 MiByte or so file will take an hour
or so to transfer from when I started it.


===
Mark Millard
marklmi at yahoo.com