Receiving "junk" data while consoling into cisco devices using db9 serial to USB adapter

Hello,
I'm studying for the a networking certification and trying to access cisco routers & switches via serial to console with a usb to DB9 adapter. It works for about 30 seconds and then something I can only describe as junk data keeps showing up. I've tried using putty and minicom through terminal and find much more success with minicom. Searching on the web I've found indicators that it's a font problem so I uninstalled most of my fonts with no avail- may have been coincidental but it worked way worse -I reinstalled them since I'm a noob and don't know what else I may have inadvertently broken :slight_smile: I am using the newest PL2303 usb to DB9 serial adapter and I tried with an older version too. I've also tried different USB ports and 4 different cisco devices with similar outcomes every time. The cable works with Win 11 and Win 10 (after installing necessary drivers). Also I didn't find anything have checked Octopi for anything pl2303 related. I'm newish to linux and very new to Arch based systems (about a month lol) so hopefully I'm overlooking something simple. Thanks for any support and much appreciation to the community as a whole!

An example of the feedback I get while I'm not even typing:
RTR-B>[email protected]@@@
% Unknown command or computer name, or unable to find computer address
RTR-B>
RTR-B>MAW0C0B
Translating "MAW0C0B"...domain server (255.255.255.255)

Here's what I sometimes get while typing:
%Unwnomr omer ,r x����x�����x������������x���������

Eventually it just becomes non responsive. Sometimes it works for 30 seconds and sometimes not at all.

The minicom settings I use are as follows (I've tried all 3 available baud rates and playing with other settings with less success) I have also used the same settings in putty- The most confusing thing is that it kind of works but fails at seemingly random intervals.

A -    Serial Device      : /dev/ttyUSB0                              |
| B - Lockfile Location     : /var/run                                  |
| C -   Callin Program      :                                           |
| D -  Callout Program      :                                           |
| E -    Bps/Par/Bits       : 9600 8N1                                  |
| F - Hardware Flow Control : Yes                                       |
| G - Software Flow Control : No                                        |
| H -     RS485 Enable      : No                                        |
| I -   RS485 Rts On Send   : No                                        |
| J -  RS485 Rts After Send : No                                        |
| K -  RS485 Rx During Tx   : No                                        |
| L -  RS485 Terminate Bus  : No                                        |
| M - RS485 Delay Rts Before: 0                                         |
| N - RS485 Delay Rts After : 0 
dmesg grep tty gives me: 
[    6.919905] systemd[1]: Created slice Slice /system/getty.
[    7.966303] usb 1-1.3: pl2303 converter now attached to ttyUSB0
[   13.918236] audit: type=1006 audit(1646304592.097:87): pid=2847 uid=0 old-auid=429496
7295 auid=966 tty=(none) old-ses=4294967295 ses=1 res=1
[   13.918242] audit: type=1300 audit(1646304592.097:87): arch=c000003e syscall=1 succes
s=yes exit=3 a0=9 a1=7ffd175207c0 a2=3 a3=0 items=0 ppid=1 pid=2847 auid=966 uid=0 gid=0
euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=(none) ses=1 comm="(systemd)" exe="/usr
/lib/systemd/systemd" key=(null)
[   26.276256] audit: type=1300 audit(1646304604.455:122): arch=c000003e syscall=321 suc
cess=yes exit=26 a0=5 a1=7ffd71711120 a2=80 a3=7ffd71711120 items=0 ppid=1 pid=690 auid=
4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=(none) ses=429496
7295 comm="NetworkManager" exe="/usr/bin/NetworkManager" key=(null)
[ 5139.565252] audit: type=1300 audit(1646309718.149:319): arch=c000003e syscall=321 suc
cess=yes exit=27 a0=5 a1=7ffd71711120 a2=80 a3=7ffd71711120 items=0 ppid=1 pid=690 auid=
4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=(none) ses=429496
7295 comm="NetworkManager" exe="/usr/bin/NetworkManager" key=(null)
[ 8739.673004] audit: type=1300 audit(1646313318.321:323): arch=c000003e syscall=321 suc
cess=yes exit=27 a0=5 a1=7ffd71711120 a2=80 a3=7ffd71711120 items=0 ppid=1 pid=690 auid=
4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=(none) ses=429496
7295 comm="NetworkManager" exe="/usr/bin/NetworkManager" key=(null)
[10539.727315] audit: type=1300 audit(1646315118.405:325): arch=c000003e syscall=321 suc
cess=yes exit=27 a0=5 a1=7ffd71711120 a2=80 a3=7ffd71711120 items=0 ppid=1 pid=690 auid=
4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=(none) ses=429496
7295 comm="NetworkManager" exe="/usr/bin/NetworkManager" key=(null)
[13284.457447] pl2303 ttyUSB0: usb_serial_generic_read_bulk_callback - urb stopped: -32
[13284.457782] pl2303 ttyUSB0: usb_serial_generic_read_bulk_callback - urb stopped: -32
[13284.567107] pl2303 ttyUSB0: pl2303_set_control_lines - failed: -19
[13284.567112] pl2303 ttyUSB0: error sending break = -19
[13284.567266] pl2303 ttyUSB0: pl2303 converter now disconnected from ttyUSB0
[13284.588709] audit: type=1131 audit(1646317863.339:327): pid=1 uid=0 auid=4294967295 s
es=4294967295 msg='[email protected] comm="systemd" exe="/usr/lib/systemd/systemd" ho
stname=? addr=? terminal=? res=success'
[13304.235233] usb 3-4: pl2303 converter now attached to ttyUSB0
[13304.330180] audit: type=1130 audit(1646317883.081:328): pid=1 uid=0 auid=4294967295 s
es=4294967295 msg='[email protected] comm="systemd" exe="/usr/lib/systemd/systemd" ho
stname=? addr=? terminal=? res=success'
[14139.781956] audit: type=1300 audit(1646318718.569:380): arch=c000003e syscall=321 suc
cess=yes exit=27 a0=5 a1=7ffd71711120 a2=80 a3=7ffd71711120 items=0 ppid=1 pid=690 auid=
4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=(none) ses=429496
7295 comm="NetworkManager" exe="/usr/bin/NetworkManager" key=(null)
[15334.771974] pl2303 ttyUSB0: pl2303_set_control_lines - failed: -19
[15334.771986] pl2303 ttyUSB0: error sending break = -19
[15334.772067] pl2303 ttyUSB0: pl2303 converter now disconnected from ttyUSB0
[15334.811402] audit: type=1131 audit(1646319913.651:457): pid=1 uid=0 auid=4294967295 s
es=4294967295 msg='[email protected] comm="systemd" exe="/usr/lib/systemd/systemd" ho
stname=? addr=? terminal=? res=success'
Finally, my system is as follows:
garuda-inxi
Kernel: 5.16.11-zen1-2-zen x86_64 bits: 64 compiler: gcc v: 11.2.0
parameters: BOOT_IMAGE=/@/boot/vmlinuz-linux-zen
root=UUID=05585052-6be0-43ce-8d5b-1679bbda1d64 rw [email protected]
quiet splash rd.udev.log_priority=3 vt.global_cursor_default=0 loglevel=3
Desktop: KDE Plasma 5.24.2 tk: Qt 5.15.2 info: latte-dock wm: kwin_x11
vt: 1 dm: SDDM Distro: Garuda Linux base: Arch Linux
Machine:
Type: Desktop System: Gigabyte product: N/A v: N/A
serial: <superuser required> Chassis: type: 3 serial: <superuser required>
Mobo: Gigabyte model: B75M-D3H v: x.x serial: <superuser required>
UEFI: American Megatrends v: F15 date: 10/23/2013
Battery:
Device-1: hidpp_battery_0 model: Logitech MX Keys Wireless Keyboard
serial: <filter> charge: 55% (should be ignored) rechargeable: yes
status: Discharging
Device-2: hidpp_battery_1 model: Logitech Wireless Mouse MX Master 3
serial: <filter> charge: 100% (should be ignored) rechargeable: yes
status: Discharging
CPU:
Info: model: Intel Core i7-3770 bits: 64 type: MT MCP arch: Ivy Bridge
family: 6 model-id: 0x3A (58) stepping: 9 microcode: 0x21
Topology: cpus: 1x cores: 4 tpc: 2 threads: 8 smt: enabled cache:
L1: 256 KiB desc: d-4x32 KiB; i-4x32 KiB L2: 1024 KiB desc: 4x256 KiB
L3: 8 MiB desc: 1x8 MiB
Speed (MHz): avg: 3533 high: 3762 min/max: 1600/3900 scaling:
driver: intel_cpufreq governor: performance cores: 1: 3489 2: 3450 3: 3762
4: 3645 5: 3649 6: 3039 7: 3613 8: 3624 bogomips: 54277
Flags: avx ht lm nx pae sse sse2 sse3 sse4_1 sse4_2 ssse3
Vulnerabilities:
Type: itlb_multihit status: KVM: VMX unsupported
Type: l1tf mitigation: PTE Inversion
Type: mds mitigation: Clear CPU buffers; SMT vulnerable
Type: meltdown mitigation: PTI
Type: spec_store_bypass
mitigation: Speculative Store Bypass disabled via prctl
Type: spectre_v1
mitigation: usercopy/swapgs barriers and __user pointer sanitization
Type: spectre_v2 mitigation: Full generic retpoline, IBPB: conditional,
IBRS_FW, STIBP: conditional, RSB filling
Type: srbds status: Vulnerable: No microcode
Type: tsx_async_abort status: Not affected
Graphics:
Device-1: AMD Bonaire XT [Radeon HD 7790/8770 / R7 360 R9 260/360 OEM]
vendor: ASUSTeK driver: radeon v: kernel alternate: amdgpu pcie: gen: 2
speed: 5 GT/s lanes: 4 link-max: gen: 3 speed: 8 GT/s lanes: 16 ports:
active: DVI-D-1,HDMI-A-1 empty: DP-1,DVI-I-1 bus-ID: 01:00.0
chip-ID: 1002:665c class-ID: 0300
Display: x11 server: X.Org v: 1.21.1.3 compositor: kwin_x11 driver: X:
loaded: ati,radeon unloaded: modesetting alternate: fbdev,vesa gpu: radeon
display-ID: :0 screens: 1
Screen-1: 0 s-res: 3640x1920 s-dpi: 120 s-size: 768x405mm (30.2x15.9")
s-diag: 868mm (34.2")
Monitor-1: DVI-0 mapped: DVI-D-1 pos: primary,top-left model: HP V27i
serial: <filter> built: 2021 res: 1080x1920 hz: 60 dpi: 82 gamma: 1.2
size: 336x598mm (13.2x23.5") diag: 686mm (27") ratio: 16:9 modes:
max: 1920x1080 min: 720x400
Monitor-2: HDMI-0 mapped: HDMI-A-1 pos: primary,bottom-r
model: LG (GoldStar) 32GK850G serial: <filter> built: 2014 res: 2560x1440
hz: 60 dpi: 109 gamma: 1.2 size: 598x336mm (23.5x13.2")
diag: 801mm (31.5") ratio: 16:9 modes: max: 2560x1440 min: 640x480
OpenGL: renderer: AMD BONAIRE (DRM 2.50.0 5.16.11-zen1-2-zen LLVM 13.0.1)
v: 4.5 Mesa 21.3.7 direct render: Yes
Audio:
Device-1: Intel 7 Series/C216 Family High Definition Audio vendor: Gigabyte
driver: snd_hda_intel v: kernel bus-ID: 00:1b.0 chip-ID: 8086:1e20
class-ID: 0403
Device-2: AMD Tobago HDMI Audio [Radeon R7 360 / R9 OEM]
vendor: ASUSTeK R7260X-DC2OC-2GD5 driver: snd_hda_intel v: kernel pcie:
gen: 2 speed: 5 GT/s lanes: 4 link-max: gen: 3 speed: 8 GT/s lanes: 16
bus-ID: 01:00.1 chip-ID: 1002:aac0 class-ID: 0403
Sound Server-1: ALSA v: k5.16.11-zen1-2-zen running: yes
Sound Server-2: PulseAudio v: 15.0 running: no
Sound Server-3: PipeWire v: 0.3.47 running: yes
Network:
Device-1: Realtek RTL8111/8168/8411 PCI Express Gigabit Ethernet
vendor: Gigabyte driver: r8169 v: kernel pcie: gen: 1 speed: 2.5 GT/s
lanes: 1 port: d000 bus-ID: 02:00.0 chip-ID: 10ec:8168 class-ID: 0200
IF: enp2s0 state: down mac: <filter>
Device-2: TP-Link Archer T3U [Realtek RTL8812BU] type: USB
driver: rtl88x2bu bus-ID: 3-3.2:4 chip-ID: 2357:012d class-ID: 0000
serial: <filter>
IF: wlp0s20u3u2 state: up mac: <filter>
Bluetooth:
Device-1: Cambridge Silicon Radio Bluetooth Dongle (HCI mode) type: USB
driver: btusb v: 0.8 bus-ID: 3-3.1.3:5 chip-ID: 0a12:0001 class-ID: e001
Report: bt-adapter ID: hci0 rfk-id: 0 state: up address: <filter>
Drives:
Local Storage: total: 931.51 GiB used: 48.71 GiB (5.2%)
SMART Message: Unable to run smartctl. Root privileges required.
ID-1: /dev/sda maj-min: 8:0 vendor: Samsung model: SSD 860 EVO 1TB
size: 931.51 GiB block-size: physical: 512 B logical: 512 B speed: 6.0 Gb/s
type: SSD serial: <filter> rev: 1B6Q scheme: GPT
Partition:
ID-1: / raw-size: 931.22 GiB size: 931.22 GiB (100.00%)
used: 48.71 GiB (5.2%) fs: btrfs dev: /dev/sda2 maj-min: 8:2
ID-2: /boot/efi raw-size: 300 MiB size: 299.4 MiB (99.80%)
used: 576 KiB (0.2%) fs: vfat dev: /dev/sda1 maj-min: 8:1
ID-3: /home raw-size: 931.22 GiB size: 931.22 GiB (100.00%)
used: 48.71 GiB (5.2%) fs: btrfs dev: /dev/sda2 maj-min: 8:2
ID-4: /var/log raw-size: 931.22 GiB size: 931.22 GiB (100.00%)
used: 48.71 GiB (5.2%) fs: btrfs dev: /dev/sda2 maj-min: 8:2
ID-5: /var/tmp raw-size: 931.22 GiB size: 931.22 GiB (100.00%)
used: 48.71 GiB (5.2%) fs: btrfs dev: /dev/sda2 maj-min: 8:2
Swap:
Kernel: swappiness: 133 (default 60) cache-pressure: 100 (default)
ID-1: swap-1 type: zram size: 15.57 GiB used: 2 MiB (0.0%) priority: 100
dev: /dev/zram0
Sensors:
System Temperatures: cpu: 29.8 C mobo: 27.8 C gpu: radeon temp: 52.0 C
Fan Speeds (RPM): N/A
Info:
Processes: 301 Uptime: 3h 56m wakeups: 31 Memory: 15.57 GiB
used: 3.57 GiB (22.9%) Init: systemd v: 250 tool: systemctl Compilers:
gcc: 11.2.0 clang: 13.0.1 Packages: pacman: 1618 lib: 459 Shell: fish
v: 3.3.1 running-in: yakuake inxi: 3.3.13
Garuda (2.5.5-1):
System install date:     2022-02-14
Last full system update: 2022-03-03
Is partially upgraded:   No
Relevant software:       NetworkManager
Windows dual boot:       No/Undetected
Snapshots:               Timeshift (maybe)
Failed units:
garuda-inxi

Please post your

garuda-inxi

as text.

If you include terminal outputs in your post please use the proper output format in your post.

Using "~" 3 times above and "~" 3 times below the text block will provide a readable, raw look.

Please edit your post and

:slight_smile:

Hallo,

Thanks for the reply! I added the "~" around all outputs with the garuda-inxi at the end of the post.

1 Like

Just from looking at your outputs, my first complete guess would be that you are missing a required font.

2 Likes

Hi! Thanks for responding.

I was thinking it may be a font issue but it does work for a while and the problem comes up independent of what the input is or what the output should be (I only posted the parts where it doesn't work).

I was thinking the drivers could be an issue since the cable I'm using have been supported since approx kernel 2.5 so I tried loading an older LTS kernel but get the same problem.

I appreciate your thoughts and I'll update this thread if I'm able to find a fix!


Edit with quick update:
I DL'd PopOS and installed as a VM and Putty worked correctly so then I opened Garuda in a VM and it worked fine as well.

Again it started looking like a font issue regular Garuda fonts mirror the vm's and it still does not work. I'm going to continue to compare my set-up to the fresh install on the vm and hopefully post the fix soon :slight_smile: worst case scenario I'll do a full re-install but there's no fun in that!

I wonder if you would be able to discover the missing font by comparing the output of fc-list from your Garuda install (the one on the metal) with the output of fc-list from one of the VM instances that appears to be working normally. If you notice a font from the VM is missing on the metal you could just download it through Pacman.

2 Likes

Hi thanks for responding. I was just getting on to post that I ended up doing a complete reinstall and everything is working as it should right now.I did compare fonts using octopi and DL'd 2 to metal that were on the vm)

Short story long for anyone interested:
I used octopi, to compare what was installed on the vm and metal and didn't find anything that led to a fix. Then I used Garuda asst to reset the listed configs and reinstall all packages- still no good. Finally, I used timehop to go back to shortly after the initial install which didn't fix the problem.

After about 9 hours of troubleshooting I decided to take 45 mins to do a clean install lol. Before any updates I installed putty to test it and it worked then, using the set-up asst I installed updates, the perf tweak, vmware, addt'l KDE components, Pamac, Libre office, SM player and VirtualBox - I used the default install settings for all except VBox I installed the (host-modules-arch) version. I periodically tested putty and it was fine. Then I connected my usb bluetooth for my headphones DL'd minicom, and google chrome and all seemed well but then It started doing then putty started misbehaving again :frowning:

I then worked backward, undoing everything as I could remember and nothing...

This led to another fresh install where I've wrote everything down as I did but installed all of my programs through octopi and updates via "sudo pacman -Syu" I got to the same as the previous install and it worked -- then I spent hours trying to break it again, writing down everything and doing resets as I accomplished it. I deleted all pertinent apps and installed them via system set-up (except I forgot pamac), I aslo ran the perf tweaks and installed additional KDE components. I also tried the virtualbox-host-dkms package but nothing.. I stayed up until 2 am trying to break it and couldn't.

This morning I did 1 last reinstall because I don't want the addtl KDE components right now pamac, discover and my wifi driver(tp link t3u) are the biggest things that I don't have installed. I'll probably forgo discover and pamac unless I end up needing them later.

This has been fun and I wish I could point to one thing causing the problem but unfortunately I can't. I'll mostly be using this build for cisco labs so I won't need to change much. Though I do live by the creed "If it ain't broke, fix it until it is".

Lastly, I understand if the thread needs to be deleted since there isn't a solution :slight_smile:

1 Like

Even if you did not fix the issue and you just gave up and installed Windows or something, the thread can still provide useful troubleshooting tips to someone who has a similar experience in the future, or just wants to read and learn.

Plus, while "I reinstalled and now it works fine" might feel like a cop-out solution or otherwise not the most rewarding fix to land on, at the end of the day it fixed your issue and thus is a solution! :blush:

4 Likes

"No solution" is no solution, and should not be promoted otherwise.

Call me jaded. :wink:

1 Like

I logged in to edit my post to include a link a video showing my problem and accidentally hit the delete button with my thumb :person_facepalming: sorry for the mistake - I wasn't able to un-delete but I could copy/paste the original.

Hi!! I found the fix/problem. During a study session It started happening (my heart sunk) thinking back, I realized that I had enabled night color control. So I disabled /restart the computer and the problem was gone. Then I opened settings and enabled it and sure enough, it happened immediately-I didn't even have to hit apply. I've ran the test a few times with alacritty and with yakuake both connected via USB to DB9 adapter. Further, I tried telnetting into the switch and there was no issue while accessing through telnet. For clarity; telnet is accomplished via IP and I was connected with an ethernet cable.

Here's the link with the video demonstrating the problem :slight_smile:

1 Like

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