[arch-general] Connection through USB to TTL Serial Cable

Sean Greenslade sean at seangreenslade.com
Thu May 21 02:13:46 UTC 2015

On Wed, May 20, 2015 at 09:41:13PM +0200, Csányi Pál wrote:
> I tried these commands:
> $ cu -s 115200 -l /dev/ttyS0
> cu: /dev/ttyS0: Line in use
> $ cu -s 115200 -l /dev/ttyS1 # ( also S2, S3 )
> Connected.
> cu: Got hangup signal
> Disconnected.
> dmesg gives me no ifnormation about such device:
> [36829.865727] Shorewall:net-fw:DROP:IN=enp0s20 OUT=
> MAC=00:1a:92:ce:61:70:00:22:02:00:07:3d:08:00 SRC=
> DST= LEN=35 TOS=0x00 PREC=0x00 TTL=48 ID=30265 DF
> PROTO=UDP SPT=50434 DPT=5093 LEN=15
> [38367.939572] usb 2-6: new full-speed USB device number 6 using ohci-pci
> Maybe the Shorewall firewall is the culprit in this case?

I can almost guarantee you that your firewall has nothing to do with it.
It is just conincidence that the previous kernel message was from the

The issue as I see it is that the serial driver kernel module seems to
not be loading. Are you running any sort of modified / alternative
kernel? Can you post the results of "uname -a" for us?

Also, a "sudo lsusb -v" might be helpful as well.


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