Category Archives: Operating Systems

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27
01
25
 3 Comments

Preventing OpenVPN clients from seeing each other

Posted by | Ubuntu | Tagged |

Listing existing rules

sudo docker exec -it dockovpn_dockovpn_1 bash
iptables --list

Chain INPUT (policy ACCEPT)
target     prot opt source               destination
ACCEPT     udp  --  anywhere             anywhere             state NEW,ESTABLISHED udp dpt:openvpn
ACCEPT     all  --  anywhere             anywhere

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination
ACCEPT     all  --  anywhere             anywhere
ACCEPT     all  --  10.8.0.0/24          anywhere
ACCEPT     all  --  anywhere             anywhere             state RELATED,ESTABLISHED

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination
ACCEPT     udp  --  anywhere             anywhere             state ESTABLISHED udp spt:openvpn
ACCEPT     all  --  anywhere             anywhere
(more…)
26
01
25
 4 Comments

Running VPN Server with Access Server in a Docker container

Posted by | Ubuntu | Tagged |

Run the docker container:

sudo docker pull openvpn/openvpn-as
sudo ufw allow 1194/udp
sudo ufw allow 943/tcp
sudo ufw allow 1443/tcp

sudo docker run -d --rm \
  --name=openvpn-as --device /dev/net/tun \
  --cap-add=MKNOD --cap-add=NET_ADMIN \
  -p 943:943 -p 1443:443 -p 1194:1194/udp \
  -v /var/lib/openvpn-as:/openvpn \
  openvpn/openvpn-as

sudo docker logs -f openvpn-as | grep "generated pass"

Auto-generated pass = "*********". Setting in db...
(more…)
23
01
25
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Migrating my Postfix configuration from Ubuntu 16.04 to Ubuntu 24.04

Posted by | Ubuntu | Tagged , |

I am not sure if I selected a right configuration, probably “No configuration” is better:

(more…)
23
01
25
 4 Comments

Configuring the access to GitHub with SSH

Posted by | Ubuntu | Tagged | 
ssh-keygen -t ed25519 -C "winappdev@gmail.com"
# /home/dmitriano/.ssh/id_rsa_github
# and empty passphrase
nano .ssh/config

Host github.com
 HostName github.com
 IdentityFile ~/.ssh/id_rsa_github

stat -c %a ~/.ssh/config
chmod 600 ~/.ssh/config
(more…)
23
01
25
 1 Comment

“ping: socket: Operation not permitted” error on a clean Ubuntu 24.04 installation

Posted by | Ubuntu |

ping did not work on my clean Ubuntu 24.04 installation showing the following error:

ping developernote.com

ping: socktype: SOCK_RAW
ping: socket: Operation not permitted
ping: => missing cap_net_raw+p capability or setuid?
(more…)
21
01
25
 5 Comments

Migrating a WordPress website from PHP 7.4 to PHP 8.3.6

Posted by | PHP, Ubuntu |

After updated my WordPress to 6.7.1 and added the following to wp-config.php

define( 'WP_DEBUG', true );
define( 'WP_DEBUG_LOG', true );

and got the following error message:

Fatal error: Uncaught Error: Call to undefined function wp_kses() in /home/devnote/www/wp-includes/functions.php:6098 Stack trace: 
#0 /home/devnote/www/wp-includes/functions.php(5579): wp_trigger_error()
#1 /home/devnote/www/wp-includes/class-wpdb.php(1333): _deprecated_function()
#2 /home/devnote/www/wp-content/sunrise.php(11): wpdb->escape()
#3 /home/devnote/www/wp-includes/ms-settings.php(47): include_once('...')
#4 /home/devnote/www/wp-settings.php(156): require('...')
#5 /home/devnote/www/wp-config.php(107): require_once('...')
#6 /home/devnote/www/wp-load.php(50): require_once('...')
#7 /home/devnote/www/wp-blog-header.php(13): require_once('...')
#8 /home/devnote/www/index.php(17): require('...')
#9 {main} thrown in /home/devnote/www/wp-includes/functions.php on line 6098
(more…)
20
01
25
 3 Comments

Creating Docker network for hosting legacy PHP websites

Posted by | Ubuntu | Tagged |

Running test Docker containers

sudo docker network create --subnet=172.20.0.0/16 legacy_net
sudo docker network ls

NETWORK ID     NAME               DRIVER    SCOPE
61aa4a19ec0c   bridge             bridge    local
7c0ebcfd4e3a   dockovpn_default   bridge    local
79ed9c355254   host               host      local
99d8bde8e488   legacy_net         bridge    local
086455f026a8   none               null      local
(more…)
15
01
25
 25 Comments

Migrating my VPS from Ubuntu 16.04 to Ubuntu 24.04

Posted by | Ubuntu |

Migrating the users and groups

Copied my groups from /etc/group:

dmitriano:x:1000:
slogpost:x:1001:www-data,bak
beauty:x:1009:www-data,bak
test1:x:1012:www-data,beauty,dmitriano,devnote,bak
test2:x:1013:www-data,bak
devnote:x:1018:www-data,bak
exchange:x:1025:
git:x:1026:www-data,bak
game:x:1027:www-data,bak
shar:x:1029:www-data,bak
bak:x:1032:
(more…)
13
01
25
 3 Comments

Using tcpdump with OpenVPN

Posted by | Ubuntu | Tagged , |

VPN service opens tun0 device in the docker container:

sudo docker exec -it 966f926484bc sh
/opt/Dockovpn # ifconfig

eth0      Link encap:Ethernet  HWaddr 02:42:AC:11:00:03
          inet addr:172.17.0.3  Bcast:172.17.255.255  Mask:255.255.0.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:20553 errors:0 dropped:0 overruns:0 frame:0
          TX packets:20539 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:14609434 (13.9 MiB)  TX bytes:14757264 (14.0 MiB)

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

tun0      Link encap:UNSPEC  HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
          inet addr:10.8.0.1  P-t-P:10.8.0.2  Mask:255.255.255.255
          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1500  Metric:1
          RX packets:7825 errors:0 dropped:0 overruns:0 frame:0
          TX packets:12572 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:500
          RX bytes:1673378 (1.5 MiB)  TX bytes:12115333 (11.5 MiB)
(more…)
12
01
25
 5 Comments

Connecting to OpenVPN from an Android device

Posted by | Ubuntu | Tagged , |

I cloned repository https://github.com/dockovpn/dockovpn and updated config/server.conf to increase the server log verbosity by setting verb to 4:

port 1194
proto %HOST_TUN_PROTOCOL%
dev tun
ca /etc/openvpn/ca.crt
cert /etc/openvpn/MyReq.crt
key /etc/openvpn/MyReq.key
dh /etc/openvpn/dh.pem
server 10.8.0.0 255.255.255.0
ifconfig-pool-persist ipp.txt
push "redirect-gateway def1 bypass-dhcp"
push "dhcp-option DNS 208.67.222.222"
push "dhcp-option DNS 208.67.220.220"
duplicate-cn
keepalive 10 120
cipher AES-256-GCM
ncp-ciphers AES-256-GCM:AES-256-CBC
auth SHA512
persist-key
persist-tun
status openvpn-status.log
verb 4
tls-server
tls-version-min 1.2
tls-auth /etc/openvpn/ta.key 0
crl-verify /etc/openvpn/crl.pem
(more…)
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