Category Archives: Ubuntu

Increasing image size in WordPress

I updated my Ubuntu 24.04 and my WordPress stopped loading images of size 1.3MB and higher.

I fixed this by adding the following:

client_max_body_size 32M;

to Nginx configuration.

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Nginx TCP proxy with SSL Termination

Obtaining the certificates

Obtain private and public keys from exported pfx file:

openssl pkcs12 -in ldaps.pfx -nocerts -nodes -out ldap.key
openssl pkcs12 -in ldaps.pfx -clcerts -nokeys -out ldap.crt
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An error occurred when accepting connection in the local socket. Code: 24

Tried the following

sysctl net.core.somaxconn
net.core.somaxconn = 4096
sudo sysctl -w net.core.somaxconn=8192

but without a success.

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Configuring a TCP proxy with Nginx on Ubuntu 24.04

Install Nginx with stream module:

sudo apt install nginx-full

The output of the command

nginx -V

should contain with-stream=dynamic.

And add the following to /etc/nginx/nginx.conf:

stream {
    server {
        listen 12345;                    # The port that Nginx listens to
        proxy_pass 192.168.0.121:389;    # Where to forward connections
    }
}
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Exporting and importing WSL distributions

Exporting

In PowerShell:

wsl --export Ubuntu Ubuntu-01.tar

where Ubuntu is the distro name.

Importing

wsl --import UbuntuA C:\Users\dmitriano\wsl\UbuntuA Ubuntu-24.01.tar

probably the folder C:\Users\dmitriano\wsl\UbuntuA should exist.

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Using lb to measure LDAP performance

Download and install latest Go:

wget https://go.dev/dl/go1.25.1.linux-amd64.tar.gz
tar xf ../distrib/go1.25.1.linux-amd64.tar.gz
realpath go
export GOROOT=/home/dmitriano/dev/tools/go
export GOPATH=$HOME/go
export PATH=$GOPATH/bin:$GOROOT/bin:$PATH

Install the package:

go install github.com/hamano/lb@latest
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Using Apache JMeter to measure LDAP performance

Extract the archive:

tar xf /mnt/c/Users/dmitriano/Downloads/apache-jmeter-5.6.3.tgz

Install Java runtime:

sudo apt install default-jre
java --version
openjdk 21.0.8 2025-07-15
OpenJDK Runtime Environment (build 21.0.8+9-Ubuntu-0ubuntu124.04.1)
OpenJDK 64-Bit Server VM (build 21.0.8+9-Ubuntu-0ubuntu124.04.1, mixed mode, sharing)
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Running v2rayN client on WSL

unzip /mnt/c/Users/dmitr/Downloads/v2rayN-linux-64.zip
sudo apt install libice6 libsm6
./v2rayN &
curl -s https://api.ipify.org
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Investigating Kerboros with kinit and Wireshark

On the domain controller:

nslookup -q=SRV _kerberos._tcp.other.local
Server:  localhost
Address:  127.0.0.1

_kerberos._tcp.other.local      SRV service location:
          priority       = 0
          weight         = 100
          port           = 88
          svr hostname   = 7-dev-de-dc16.other.local
7-dev-de-dc16.other.local       internet address = 10.15.7.16
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Squid unexpectedly stopped working

Squid unexpectedly stopped working with my home internet connection. I created a temporary user:

cd /etc/squid/
sudo htpasswd -B squid-password temp
sudo service squid reload

tried the following command

curl -v -x https://developernote.com:3129 --proxy-user temp:<password> -I https://api.ipify.org/

with another internet provider and it succeeded.

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