In Redmine, by default you are always logged out after a very short period of time.
You can fix this by logging in as an administrator and opening Administration -> Settings -> Authentication and setting Autologin to 365 days. You can also choose a lower value if you want sessions to automatically expire sooner.
In multiple models of MikroTik routers running RouterOS v7.5 I got Error: Connection refused when running simple SSH port forwarding commands such as
ssh [email protected] -L 8080:192.168.178.1:80
but in the RouterLS log I could see multiple local forwarding forbidden error messages:
In this case, the solution was simple: Go to IP -> SSH in WebFig or Winbox and set Forwarding Enabled to Both and click Apply.
If you have already set Forwarding Enabled to Both or Local, on one of my routers this setting wasn’t properly activated – possibly after a RoutreOS upgrade. In order to fix this, set Forwarding Enabled to no, click Apply, then set Forwarding Enabled to Both and click Apply again. For me, this fixed the issue of being unable to do SSH port forwarding.
In oder to print new-style (SHA256) fingerprints such as Is7oLjYcKue/zRjPKy9gQma/9F24KGaMPHbGberPGAw, use
for i in /etc/ssh/ssh_host_*_key; do sudo ssh-keygen -l -E sha256 -f "$i"; done
Example output:
1024 SHA256:SAhM78NWwqoYS/nRByGs1oqJxrX8fZL/PR/F5oX3QWs root@myserver (DSA) 256 SHA256:V/+9872Yg1i2Q4i7Nt4ef5R06lAuzT6qKemaQEt8EJQ root@myserver (ECDSA) 256 SHA256:Is7oLjYcKue/zRjPKy9gQma/9F24KGaMPHbGberPGAw root@myserver (ED25519) 2048 SHA256:AORSBitRPpwXrbTQzP0Mb/OBXyK+V6gyWf0S4bIh7Ys root@myserver (RSA)
In order to print old-style (MD5) fingerprints such as 5c:19:8b:94:44:5e:b6:15:e6:32:cc:3c:9b:38:6b:4c, use this command:
for i in /etc/ssh/ssh_host_*_key; do sudo ssh-keygen -l -E md5 -f "$i"; done
Example output:
1024 MD5:6d:f8:17:9b:4a:f5:ec:14:04:68:22:9c:ca:2c:a1:19 root@myserver (DSA) 256 MD5:5c:19:8b:94:44:5e:b6:15:e6:32:cc:3c:9b:38:6b:4c root@myserver (ECDSA) 256 MD5:45:dd:7f:91:89:67:ab:2d:ee:a2:f8:9e:18:68:5b:0d root@myserver (ED25519) 2048 MD5:1b:b2:54:3a:10:51:17:b4:49:af:73:c2:da:d6:fc:df root@myserver (RSA)
Not even two years after the 1000th blogpost, this is TechOverflow’s 2001th blog post – and certainly not the last one.
It took 8 years to reach 1000 posts and 7500 visitors a day – and not even two more years to reach up to 13200 visitors in one day (typical work days have around 12.5k visitors), with an upwards trend:
Your wordpress page or other PHP application displays a critical error, with the following message:
2022/09/17 04:11:49 [error] 98082#98082: *1053 FastCGI sent in stderr: "PHP message: PHP Fatal error: Uncaught Error: Call to undefined function simplexml_load_file() in /var/sites/mysite.com/wp-content/plugins/otgs-installer-plugin/vendor/otgs/installer/includes/class-wp-installer.php:870
Install the php[VERSION]-xml package for the PHP version that is running wordpress.
For example:
sudo apt -y install php8.1-xml
When loading your wordpress page, you see the following message:
Your PHP installation appears to be missing the MySQL extension which is required by WordPress.
Install the php[VERSION]-mysql package for the PHP version that is running wordpress.
For example:
sudo apt -y install php8.1-mysql
According to theworldmaterial.com the density of V4A stainless steel is approximately 8000 kg/m³ or 8.0 g/cm³
Run this command to install the ZeroTier client on Rasbian. You can use the same command to install ZeroTier on virtually any Linux platform.
curl -s https://install.zerotier.com | sudo bash
Source: ZeroTier installation website
In Arduino, if you have a std::string:
std::string str = "test";
you can’t directly print it – trying to do so leads to the following error messages:
src/main.cpp: In function 'void setup()':
src/main.cpp:122:22: error: no matching function for call to 'HardwareSerial::println(std::__cxx11::string&)'
Serial.println(cert);
^
In file included from /home/uli/.platformio/packages/framework-arduinoespressif32@src-76bf6cf11a70195daa934985b7bd68e2/cores/esp32/Stream.h:26,
from /home/uli/.platformio/packages/framework-arduinoespressif32@src-76bf6cf11a70195daa934985b7bd68e2/cores/esp32/Arduino.h:166,
from src/main.cpp:1:
/home/uli/.platformio/packages/framework-arduinoespressif32@src-76bf6cf11a70195daa934985b7bd68e2/cores/esp32/Print.h:96:12: note: candidate: 'size_t Print::println(const __FlashStringHelper*)'
size_t println(const __FlashStringHelper *);
^~~~~~~
/home/uli/.platformio/packages/framework-arduinoespressif32@src-76bf6cf11a70195daa934985b7bd68e2/cores/esp32/Print.h:96:12: note: no known conversion for argument 1 from 'std::__cxx11::string' {aka 'std::__cxx11::basic_string<char>'} to 'const __FlashStringHelper*'
/home/uli/.platformio/packages/framework-arduinoespressif32@src-76bf6cf11a70195daa934985b7bd68e2/cores/esp32/Print.h:97:12: note: candidate: 'size_t Print::println(const String&)'
size_t println(const String &s);
You can use .c_str() to convert it to a NUL-terminated char* which can be printed directly:
Serial.println(str.c_str());
If you have an Arduino String:
String arduinoStr = "test123";
you can easily convert it to a std::string by using:
std::string stdStr(arduinoStr.c_str(), arduinoStr.length());
The std::string constructor will copy the data, therefore you can de-allocate the Arduino String instance safely.
For new projects, you should exclusively use LittleFS, period.
The only reason why you would you SPIFFS at all if you have data stored on SPIFFS and can’t easily migrate to LittleFS.
LittleFS is just better than SPIFFS in every regard and SPIFFS will at some point in time be deprecated anyways.
After you have initialized LittleFS (see ESP32 Filesystem initialization code example (LittleFS)) you can get the filesize by first opening the file, and then calling .size() on the opened file. Don’t forget to close the file afterwards.
auto file = LittleFS.open(filename, "r"); size_t filesize = file.size(); // Don't forget to clean up! file.close();
size_t LittleFSFilesize(const char* filename) {
auto file = LittleFS.open(filename, "r");
size_t filesize = file.size();
// Don't forget to clean up!
file.close();
return filesize;
}Serial.println(LittleFSFilesize("/cert.pem"));
When compiling your PlatformIO project, you see a compiler error like
src/main.cpp:6:10: fatal error: esp_https_server.h: No such file or directory
at the following line:
#include <esp_https_server.h>
The ESP32 HTTPS server library is not included with the older versions of arduino-espressif32. The solution therefore is to use a more recent version of the platform library such as version 2.0.4. In order to do that, add the following line to your platformio.ini:
platform_packages = framework-arduinoespressif32 @ https://github.com/espressif/arduino-esp32.git#2.0.4
platformio.ini example:[env:esp32dev] platform = espressif32 platform_packages = framework-arduinoespressif32 @ https://github.com/espressif/arduino-esp32.git#2.0.4 board = esp32dev framework = arduino monitor_speed = 115200
In RouterOS, you can simply import .pem files using /certificate import no matter if the file contains a certificate and/or a private key.
First, upload them either via WebFig (Files) or via SCP to the filesystem of the Router.
We will assume the certificate is called cert.pem while the private key is called privkey.pem
After that, import the certificate and the private key, one after another:
/certificate/import file-name="cert.pem" passphrase="" name="mikrotik.mydomain.net" /certificate/import file-name="privkey.pem" passphrase="" name="mikrotik.mydomain.net"
This will tell you that first the certificate and then the private key have been successfully imported:
[admin@MyRouter] > /certificate/import file-name=cert.pem passphrase="" name="mikrotik.mydomain.com"
certificates-imported: 1
private-keys-imported: 0
files-imported: 1
decryption-failures: 0
keys-with-no-certificate: 0
[admin@MyRouter] > /certificate/import file-name=privkey.pem passphrase="" name="mikrotik.mydomain.com"
certificates-imported: 0
private-keys-imported: 1
files-imported: 1
decryption-failures: 0
keys-with-no-certificate: 0
This is an example of using a Here document (Heredoc) in bash to write an inline string to a file.
cat <<EOF >/etc/dhcp/dhcpd.conf
authoritative;
default-lease-time 86400;
max-lease-time 86400;
subnet 192.168.99.0 netmask 255.255.255.0 {
range 192.168.99.100 192.168.99.150;
option routers 192.168.99.1;
option domain-name-servers 192.168.99.1;
option domain-name "local";
}
EOF
Before you call WiFi.begin(...), call this:
if (!WiFi.config(
IPAddress(192, 168, 19, 5), // ESP's IP address
IPAddress(192, 168, 19, 1), // Gateway
IPAddress(255, 255, 255, 0), // IP Address
IPAddress(192, 168, 19, 1) // DNS server
)) {
Serial.println("Failed to set static IP");
}and replace the IP address etc with the static
This is based on our previous post on How to fix ESP32 not connecting to the Wifi network:
#include <Arduino.h>
#include <WiFi.h>
void setup() {
Serial.begin(115200);
WiFi.begin("MyWifiSSID", "MyWifiPassword");
// Set static IP
if (!WiFi.config(
IPAddress(192, 168, 19, 5), // ESP's IP address
IPAddress(192, 168, 19, 2), // Gateway
IPAddress(255, 255, 255, 0), // IP Address
IPAddress(192, 168, 19, 1) // DNS server
)) {
Serial.println("Failed to set static IP");
}
// Wait for wifi to be connected
uint32_t notConnectedCounter = 0;
while (WiFi.status() != WL_CONNECTED) {
delay(100);
Serial.println("Wifi connecting...");
notConnectedCounter++;
if(notConnectedCounter > 150) { // Reset board if not connected after 5s
Serial.println("Resetting due to Wifi not connecting...");
ESP.restart();
}
}
Serial.print("Wifi connected, IP address: ");
Serial.println(WiFi.localIP());
}
void loop() {
// put your main code here, to run repeatedly:
}
Simply use xTaskGetCurrentTaskHandle()
#include <freertos/FreeRTOS.h> #include <freertos/task.h> TaskHandle_t myTaskHandle = xTaskGetCurrentTaskHandle();
In C++, you are declaring an enum class like this:
enum class Shape : uint8_t {
Circle = 0,
Square = 1
};
but when you try to compile the project, you see an error message like
include/Shape.hpp:4:6: warning: elaborated-type-specifier for a scoped enum must not use the 'class' keyword
enum class Shape : uint8_t {
~~~~ ^~~~~
-----The issue here is that you are deriving the enum class from another type – uint8_t in this example – but that type has not been declared.
So the solution is to #include the header where the type from which the enum class is inherited.
In our example – for the type uint8_t and for many other integral types such as int32_t , you can do that by adding
#include <cstdint>
before the enum class declaration.
This minimal example creates a threading.Lock and locks it using a with statement. This is the simplest way of using a Lock.
from threading import Lock
lock = Lock()
with lock:
print("Holding the lock!")
When storing real-time data from a Python script, it is often helpful to have a timestamp consisting of both date & time in your filename, such as
mydata-2022-09-02_00-31-50-613015.csv
With this specific syntax we avoid special characters which are an issue on Windows operating systems, and we provide a lexically sortable filename
In Python you can do that using UliEngineering.Utils.generate_datetime_filename() from the UliEngineering library.
First, install the UliEngineering library using
pip install UliEngineering
Now you can generate your filename using
from UliEngineering.Utils.Date import * filename = generate_datetime_filename() # example: filename == 'data-2022-09-02_03-02-00-045587.csv'
or you can just open the file using with open():
with open(generate_datetime_filename(), "w") as outfile:
# Example of what you can do with outfile
outfile.write("test")You can use this simplified version which does not support fractional seconds and will generate filenames like
data-2022-09-02_00-31-50.csv
Source code (simple version – the UliEngineering version is more robust and supports more features):
from datetime import datetime
def generate_datetime_filename(label="data", extension="csv", dt=None):
if dt is None:
dt = datetime.now()
return f"{label}-{dt.year}-{dt.month:02d}-{dt.day:02d}_{dt.hour:02d}-{dt.minute:02d}-{dt.second:02d}.{extension}"