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Messages - Mad Penguin

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General Discussion / Re: Boot Times & Run Times
« on: January 25, 2022, 11:24:31 pm »
So .. there are a couple of aspects to this which skew the figures back and forth a little. Overall boot speed is a combination of latency (aka seek time) and throughput. When a system boots, it tends to read from a number of different areas of the disk, which means on a HDD the heads need to move quite a bit, so latency becomes quite important relative to the sequential read speed. So where USB drives potentially lose out on throughput, assuming the storage is flash based, they tend to catch back up again on low seek latency.

Actually getting 60Mb on a USB2 would be pretty good going, I've had an old Mac here running on an external SSD via USB2 and the best it sees is around 35Mb/sec (historically this feels about right for Linux too). As for USB3, I looked at the high throughput speeds and was very surprised to find I couldn't get anywhere near this, specifically on a Raspberry Pi 400. (top-end seems to be more like 250Mb/sec) I'm not certain, but from what I can see there are two USB3 specs, 3.0 and 3.1. It "seems" that 3.0 actually delivers ~ 250Mb/sec and you need 3.1 to get any closer to the published maximums .. but my takeaway was generally "avoid mass-storage on USB" ..

So .. HDD at 100Mb/sec with 5ms seek time vs USB flash at 35Mb/sec with 0.2ms seek time, who boots faster? I guess it depends on the particular install, desktop environment etc etc .. but for a desktop, I'd probably lean towards the USB - although I'm not sure there would be that much in it.

In terms of 'faster once installed', then if it's a modern system, and assuming that system has onboard NVMe M.2 type storage (which I think is pretty standard) then seek times will be quicker (not sure how much), but the throughput is indeed going to be a lot faster. The sequential read speed on my machine is ~ 3000Mb/sec, which would make it ~ 100x faster than a USB2 flash. It's not going to boot 100x faster because the difference in latency isn't going to be anything like that, but I would expect it to be significantly quicker.

Linux Support / Re: HALP. cannot set up vpn on ubuntu
« on: January 21, 2022, 02:13:43 pm »
Hi dexxin,
It may be that you need to use "openvpn" specifically, but if not, you might like to consider; , I struggled with OpenVPN for many (many) years before finding tinc. I've now been on tinc for probably 4-5 years, the two have quite different characteristics, but I think I would struggle to find a point where OpenVPN wins ..

Linux Support / Re: SSH Key authentication
« on: January 21, 2022, 01:13:26 pm »
As I understand it; on most desktops (?) when you log in it should activate the desktop's chosen keychain application and it should prompt you for a password to unlock your keychain. Once unlocked, subsequent use of the keychain should be transparent. (i.e. no password needed at the point of use, because it pulls it from the keychain) So to add your private ssh key to your keychain;
Code: [Select]
ssh-add .ssh/<private key>
(then enter your password) To ensure it's use, in .ssh/config;
Code: [Select]
Host *
   AddKeysToAgent yes
   IdentityFile ~/.ssh/<private key>
As for not using a password (  :)  ) , consider that some random bit of code in some random bit of software that you've installed onto your computer decided it's going to issue a single command at some point in it's lifecycle to copy .ssh/* to some random location out there on the Internet. If it were to happen (looking at toolchain polution at the moment, the odds seem high) , a passwordless key is potentially going to give a remote attacker passwordless access to your remote systems. (a short password, pretty much the same) Current recommendation seems to be >= 15 characters, avoiding dictionary words, dates etc. I know it's a pain (esp. if agent/keychain isn't set up) but for my $0.02, no passwords isn't worth the risk  :)

=== UPDATE ===
I appreciate this is a bit vague, bit it does differ from system to system. Just to prove the point I setup a clean machine to provide a concrete example. Assuming you have a working ssh setup and have done as described above, and assuming you're using a KDE-Plasma desktop (which is my current choice of desktop), you also need to create; ~/.config/autostart-scripts/
Code: [Select]
ssh-add $HOME/.ssh/id_rsa $HOME/.ssh/anotherkey </dev/null
Make sure it's excutable;
Code: [Select]
chmod a+x ~/.config/autostart-scripts/
Then log out .. when you log back in, it should ask if you want to allow the desktop to unlock the Wallet, select allow Always, then it will ask for your ssh password(s), make sure you click the "save" tickbox under the password. If you check a "ssh" command, it should now work without asking for a password. If you now log out and in again, it should ask for your wallet password to unlock your wallet (if your wallet password is different from your login password), but after that you should be good to go ... If you now launch the KDE Wallet manager, you should see an entry for "ksshaskpass", and if you open that, under password you should see your key(s).

General Discussion / Re: Linux Foundation online course
« on: December 11, 2021, 02:27:01 pm »
At the risk of sounding "old" .. they don't make documentation like they used to ....

It feels a little as tho' many years ago, I guess because we didn't have 'the Internet' and all we had was dead trees, documentation had to be 'better' than it is today. When I want to learn something these days, my first port of call is always Google, picking up a book is kind of a second choice.

The first complete(ish) Unix system I installed on my computer was called "Coherent", and one of the things that made it really cool was the manual that came with it. Now although Coherent is no more, and although it's a little different to Unix, the manual is (from memory) first-class and in terms of basic theory, not all that much has changed between then and now. If it's of any use to anyone, you can still see it (online) here;

The Linux Documentation Project sports many good (free) online resources, although the site looks somewhat dead, the quality of the PDF's isn't too bad from an educational perspective, albeit in some cases maybe a little dated.
Unfortunately, about 15 or so years ago, many aspects of Linux (like documentation) seemed to become quite 'commercial' in nature, and although there are many good books available today, they're generally not free. It's an interesting thought that although many current authors expect to get paid for their work, the authors of the original Linux documentation (and code) were generally doing it for the community (and were unpaid). [not necessarily a critique, just an observation] .. I do wonder ultimately where this apparent shift in attitude will lead ...

Linux Support / Re: Rsync
« on: September 02, 2021, 01:48:17 pm »
Just a couple of comments on pattern matching, as Keith pointed out, although Windows pattern matching "looks" like Linux/bash pattern matching, there are some subtle differences. If you try the following;
Code: [Select]
echo *
echo .*
echo *.*
  • You will see that "*" matches all files (that do NOT begin with '.')
  • ".*" will match all files that DO begin with "."
  • And "*.*" will match all files that contain a "." (but do not begin with a dot)

Linux Support / Re: Keyboard and mouse problems
« on: August 03, 2021, 10:10:39 am »
Ok, for what it's worth;

I'm still using this unaltered .. probably average of 8h/day but runs 24x7 .. had exactly zero problems with it .. using KUbuntu  :)

Ironically, the "most-used" feature of my Xerox is scan to email .. insert document, enter email address on printer console, press scan. I'd not even considered the scanning feature at the outset, but it's turned out to be incredibly useful. Seems to be a feature of many of the new multi-function printers, I maybe I'm getting old .. keeping up is becoming hard ..  :(

Hi Keith .. so I'm not sure where your £/page comes from, but historically I avoid figures coming from the manufacturer when it comes to ink or printing costs. I tend to use "" as they seem to sell almost everything and don't seem to lean in any particular direction. If you take a look at their printer specs, they include a cost/page for every printer.

I don't know how accurate these numbers are, but after having worked with a bunch of different inkjets, they don't seem unrealistic. As a rule of thumb, I tend to find lasers 1/2 to 1/3 the cost of inkjets (per page) .. in practice with cartridge failures etc, my personal experience is that over the short term or for very infrequent use, inkjets can be much more cost effective. If on the other hand you're keeping the printer for a while or want to do lots of printing, over time it tends to even out ... that said mileage will depending on the printer .. :)

Linux Support / Re: Can't get Smartmontools
« on: July 31, 2021, 12:03:00 pm »
Smartmontools includes a background daemon that will [optionally] periodically monitor your storage devices and attempt to report any problems it finds .. via email (!) .. so just be aware, if you opt not to install  some sort of basic email facility on your machine, you may not get notifications if impending doom should one of you drives start to fail ..  ;)

Linux Support / Re: Keyboard and mouse problems
« on: July 26, 2021, 03:32:43 pm »
Sure, if all your fans are running, heat shouldn't be an issue .. but chips typically don't run from cold for more than a minute or two without a working heat-sink / fan, so any sort of failure in that department can easily be terminal ..  :)

Hardware Compatibility / Re: HP Envy 5030 'not printing' problem.
« on: July 25, 2021, 02:44:09 pm »
Cool, nice to see working solutions ..  :)
Some of the multi-function all-in-one devices work pretty well, but there is a tendency to need drivers or additional drivers which doesn't always make the printing experience totally seamless. If anyone is on the lookout for a seamless solution, this might be worth a read;

Linux Support / Re: Keyboard and mouse problems
« on: July 25, 2021, 01:02:51 pm »
Hi, could be hardware, but it's always worth checking /var/log/syslog and /var/log/kern.log around the time the machine crashed to see if there is anything system or hardware related mentioned in any context. That aside, memory is always a good thing to check, but in this weather, also temperature. Internal fans are always subject to failure which can result in overheating.

If you don't have it already installed, "lm-sensors" is a good package to have, once installed "sensors-detect" will set things up. Then you should get something like this, which should give you an idea of whether your machine is running hot;
Code: [Select]
$ sensors 
Adapter: PCI adapter
Tdie:         +33.5°C  (high = +70.0°C)
Tctl:         +33.5°C 
I've just noticed that Ubuntu isn't installing "smartmontools" by default, this is also a good one to have. Unlikely to cause this issue but it's always worth keeping an eye on your storage, for example;
Code: [Select]
$ smartctl -A /dev/sdc 
smartctl 7.1 2019-12-30 r5022 [x86_64-linux-5.4.0-80-generic] (local build)
Copyright (C) 2002-19, Bruce Allen, Christian Franke, [url=][/url]
SMART Attributes Data Structure revision number: 16
Vendor Specific SMART Attributes with Thresholds:
  1 Raw_Read_Error_Rate     0x002f   200   200   051    Pre-fail  Always       -       1
  3 Spin_Up_Time            0x0027   178   170   021    Pre-fail  Always       -       4058
  4 Start_Stop_Count        0x0032   100   100   000    Old_age   Always       -       172
  5 Reallocated_Sector_Ct   0x0033   200   200   140    Pre-fail  Always       -       0
  7 Seek_Error_Rate         0x002e   200   200   000    Old_age   Always       -       0
  9 Power_On_Hours          0x0032   004   004   000    Old_age   Always       -       70656
 10 Spin_Retry_Count        0x0032   100   100   000    Old_age   Always       -       0
 11 Calibration_Retry_Count 0x0032   100   100   000    Old_age   Always       -       0
 12 Power_Cycle_Count       0x0032   100   100   000    Old_age   Always       -       172
192 Power-Off_Retract_Count 0x0032   200   200   000    Old_age   Always       -       85
193 Load_Cycle_Count        0x0032   200   200   000    Old_age   Always       -       86
194 Temperature_Celsius     0x0022   106   098   000    Old_age   Always       -       41
196 Reallocated_Event_Count 0x0032   200   200   000    Old_age   Always       -       0
197 Current_Pending_Sector  0x0032   200   200   000    Old_age   Always       -       0
198 Offline_Uncorrectable   0x0030   100   253   000    Old_age   Offline      -       0
199 UDMA_CRC_Error_Count    0x0032   200   200   000    Old_age   Always       -       0
200 Multi_Zone_Error_Rate   0x0008   100   253   000    Old_age   Offline      -       0
Again, in this weather, worth keeping an eye on #194, different drives have different temperature tolerances and best-case for running 'hot' is that it's likely to decrease you drive's life expectancy.

I still have memories from the early 90's of responding to a technical support request listing an apparent CPU lockup which wouldn't correct itself with a power cycle. On opening up the machine I found that the CPU fan had failed (well, my best guess) which had caused the CPU to get so hot the entire plastic CPU assembly (and fan) had melted and become a puddle of plastic covering the middle of the motherboard. Heat kills!   :(

Hi Webret, it would help if you were able to detail what it is you are trying to accomplish with regards to "seeing packages". Netstat and Wireshark are great tools in context, but are more for real-time traffic analysis .. you might also like to take a look at "ntop", which is orientated more towards traffic analysis "after the fact", but does provide some detail with regards to traffic flow per application.

Sample screenshot here;

Website is here;

I know it looks a bit professional, but as far as I'm aware it's available under GPL3 license. (i.e. Open Source)
(apt install ntopng on Ubuntu)

Linux Support / Re: Rsync
« on: July 15, 2021, 09:48:36 am »
You could try adding "--progress" to see how far it gets, however it would seem possible that your memory stick / flash drive is worn (or full). Have you tried backing it up to an alternate location? Flash storage devices historically employ lots of different mechanisms to handle the limited write cycles feature of flash, i.e. that you can only write to each location up to (n) times" where (n) can be as low as 1000. Ultimately, despite lots of space showing as free on the device, it can effectively have run out of available writable blocks .. and drivers can be pretty "bad" at handling this edge-case - infinite retries are not unknown.

Linux Support / Re: Frequent crashing of 18.04
« on: July 15, 2021, 09:41:49 am »
Ok, so whereas it's entirely possible that your installation software is at issue, it's not generally the cause of issues like this. The two most likely options are;
  • Driver incompatibility
  • Hardware fault (specifically, memory, but possibly disk)
The former historically being the "most" likely. If you look in "/var/log" following a crash, specifically at files "syslog" and "kern.log", if you can identify in the log files "when" the crash happened and look at log entries leading up to this point, it may give some indication of what caused the problem. (whether it be memory or a driver) Unless you are doing something particularly exotic, video drivers are often good candidates for mouse / screen freezes.

As Emegra pointed out, the other thing to try is a memory test .. when you first power on the machine the BIOS will have the facility to check it's memory before booting, sometimes this is a keypress, sometimes you first need to enter the BIOS to enable the feature. If you run this before booting (it can take a few minutes) it should prove / eliminate memory as a potential issue.

If it turns out you have a video issue (he says looking in the general direction of NVIDIA  ??? )  the first port of call would be to try different drivers. Some drivers have propriety AND open source variants and the relative features / stability vary. In the past I've found that some propriety drivers (NVIDIA in particular) have different versions and it can be critical to the stability of your machine you get the right version of the driver for your specific video card. If in doubt, revert to the open source version of the drivers to first establish this is the issue.

As a rule of thumb, if you can install a package, it was probably Ok at source, so if you didn't get any errors during installation, any software corruption is likely to be a storage issue within your machine. If the drive (HDD or SSD) is > 3 years old, personally I'd just swap it out before going any further, but at the very least it's worth running a non-destructive disk check on the entire disk just to make sure it reads reliably. Many people will tell you "I've never had a hard disk fail!", but just looking at the shelf behind be, I have ~ 40 units (>30Tb) of failed HDD's, and half a dozen smaller SSD's ... average lifespan on modern disks (for me) seems to be 3-5 years.

One more thought, how much memory / swap do you have? Some desktop options (I won't say "Gnome" but ..) eat memory and can get upset if you run out. Minimum practical memory is probably 4G + 2G Swap, but I'd recommend "at least" 8G. If you have less than 8Gb, you might want to consider XUbuntu. (I have seen lack of memory cause lockups, despite that not being expected behaviour)

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