Introduction Discover the world of Linux bin bash shell in this comprehensive guide. Learn from basic to advanced examples, understand shell scripting, and explore frequently asked questions. The Linux bin bash shell is an essential component of the Linux operating system, providing users with a command-line interface to interact with the system. Whether you are a beginner looking to understand the basics or an advanced user seeking to refine your scripting skills, this guide offers a detailed exploration of the bin bash shell. What is the Linux Bin Bash Shell? Understanding the Shell The shell in Linux is a command-line interpreter that executes user commands. The term "bash" stands for Bourne Again Shell, an enhanced version of the original Unix shell created by Steve Bourne. It is the most popular shell in Linux, with its executable located at /bin/bash . Why Use Bash? Versatility : Bash is widely used for its simplicity and power. Scripting : Automate tasks through shell...

Introduction While using Zimbra , you might encounter the "Client host rejected: Access denied" error, which can disrupt your workflow. This is a common issue that can be resolved easily if you understand the causes and the solutions. This article provides a detailed guide on how to fix this error on Zimbra, helping you quickly resume your work smoothly. Zimbra client host rejected Access denied error log Dec 19 01:21:28 mail postfix/amavisd/smtpd[5106]: NOQUEUE: reject: CONNECT from unknown[192.168.1.113]: 554 5.7.1 <unknown[192.168.1.113]>: Client host rejected: Access denied; proto=SMTP Dec 19 01:21:28 mail postfix/amavisd/smtpd[5106]: lost connection after CONNECT from unknown[192.168.1.113] Dec 19 01:21:28 mail postfix/amavisd/smtpd[5106]: disconnect from unknown[192.168.1.113] Allow the network " 192.168.1.0/24 " of client host for zimbraMtaMyNetworks attribute [zimbra@mail ~]$ zmprov ms `zmhostname` zimbraMtaMyNetworks "127.0.0.0/8 192.1...

Introduction Zimbra is a popular open-source email server solution used by many organizations worldwide. However, like any software, it can encounter issues that disrupt its functionality. One such common issue is the " Zimbra ERROR zclient IO ERROR."  This error can cause significant disruptions in email services, impacting communication and productivity. In this comprehensive guide, we'll explore the causes of this error and provide solutions ranging from basic troubleshooting to advanced fixes. Understanding the Zimbra ERROR zclient IO ERROR What is the Zimbra ERROR zclient IO ERROR? The "Zimbra ERROR zclient IO ERROR" is a connectivity issue between the Zimbra client and the server. This error typically indicates problems with network connections, server configurations, or client settings that prevent successful communication. Common Symptoms Inability to send or receive emails Frequent disconnections from the email server Error messages indicating IO issue...

Introduction Managing spam and unwanted emails is crucial for maintaining a secure and efficient email system. For Zimbra users, the ability to blacklist emails based on specific subject lines is a powerful feature. This guide delves into the process of leveraging this functionality, ensuring your inbox remains free from undesired messages. Whether you're an admin or a regular user, mastering this tool will enhance your email management capabilities. Why Blacklist Emails Based on Subject? Filtering emails by subject provides an additional layer of control over your inbox. This feature is especially useful when dealing with recurring spam or malicious emails that share similar subject patterns. Here are the primary benefits: Enhanced Spam Management : Quickly block unwanted emails. Increased Productivity : Reduce distractions from irrelevant messages. Improved Security : Prevent phishing and malicious content. Setting Up Zimbra to Blacklist Emails via Subject Prerequisites Before yo...

This day, I running vagrant up in my laptop then isuse. I can not start VM in vagrant. My laptop use windows 10. Error code as below: $ vagrant.exe up There was an error while executing `VBoxManage`, a CLI used by Vagrant for controlling VirtualBox. The command and stderr is shown below. Command: ["showvminfo", "600a47e1-9637-4054-89c2-df3e5bf8f691"] Stderr: VBoxManage.exe: error: Code ERROR_MOD_NOT_FOUND 0x8007007E (0x8007007E) - ERROR_MOD_NOT_FOUND 0x8007007E (extended info not available) VBoxManage.exe: error: Context: "GetGuestOSType(osTypeId.raw(), osType.asOutParam())" at line 575 of file VBoxManageInfo.cpp Solve problem There was an error while executing `VBoxManage`, a CLI used by Vagrant for controlling VirtualBox. Step 1: Right click on VirtualBox.exe and select Properties. Step 2: Click the Compatability tab. Click the button that says 'Change settings for all users'. Step 3: In the new window that pops up check ...

Introduction If you are a Zimbra email administrator or user, encountering the Zimbra Error 450 4.7.1 sender reject can be frustrating. This error typically arises when a sender's email is rejected due to policy restrictions or server misconfigurations. In this article, we delve into the root causes, practical fixes, and preventive measures to tackle this common issue effectively. Zimbra, a robust and versatile email platform, is widely used for its flexibility and scalability. However, errors like 450 4.7.1 can disrupt communication and productivity. Let’s explore how to troubleshoot and resolve this problem step-by-step. In this tutorial, we will explore how to solve the problem "Zimbra Error 450 4.7.1 sender reject" on Zimbra MTA. Error Description The error message appears as follows: Feb 10 16:16:33 sd-15xxx postfix/smtpd[1832]: NOQUEUE: reject: RCPT from unknown[x.x.x.x]: 450 4.7.1 Client host rejected: cannot find your hostname, [x.x.x.x]; from=<someone@sen...

Introduction Managing email accounts effectively is a critical task for system administrators using Zimbra, an open-source collaboration suite. Identifying inactive accounts ensures optimal server performance, security, and storage efficiency. In this article, we’ll explore how to check accounts that are not active in Zimbra using a streamlined approach. Why Check for Inactive Accounts in Zimbra? Benefits of Identifying Inactive Accounts Inactive accounts can lead to various issues, including: Wasted Storage : Dormant accounts consume server space. Security Risks : Unused accounts may become vulnerable to unauthorized access. Operational Efficiency : Regular cleanup enhances system performance and maintainability. By identifying and addressing inactive accounts, administrators can maintain a secure and efficient email environment. Step-by-Step Guide to Checking Inactive Accounts in Zimbra Prerequisites Before you begin, ensure you have: Admin Access : Permissions to execute commands on...

In this tutorial, How to install 3proxy on centos 7 ? How to configure 3proxy for multiple 3G USB modems. Pre-install The package for Centos 7 $ sudo yum update $ sudo yum -y install wget nano epel-release net-tools $ sudo yum -y groupinstall "Development Tools" $ sudo systemctl stop firewalld && systemctl disable firewalld # For example, My LAB turn off firewalld. Installing 3proxy on Centos 7 $ wget https://github.com/z3APA3A/3proxy/archive/0.8.12.tar.gz $ tar zxfv 3proxy.gz $ cd 3proxy-0.8.12/ $ sudo make -f Makefile.Linux $ sudo mkdir /usr/local/3proxy $ sudo cp src/3proxy /usr/local/3proxy/ $ sudo chmod +x /usr/local/3proxy/3proxy Creating the main configurator 3proxy.cfg file. $ sudo nano /usr/local/3proxy/3proxy.cfg And paste the following content: #!/bin/bash IPv4=`ip addr list enp0s3 | grep " inet " | head -n 1 | cut -d " " -f 6 | cut -d / -f 1` IP=`ip addr list ppp0 | grep " inet " | head -n 1 | cut -d " ...

Introduction Learn how to install wvdial on Ubuntu 18.04 with our detailed, step-by-step guide. Perfect for setting up your USB 3G/4G Modem. Includes troubleshooting tips and frequently asked questions. If you're working with USB 3G/4G modems on Ubuntu 18.04, you may find that wvdial is an essential tool for managing your modem connections. However, installing wvdial can be tricky, especially when it comes to resolving dependency issues. This comprehensive guide will walk you through the process of installing wvdial on Ubuntu 18.04, addressing common problems, and ensuring a smooth setup. Why Install wvdial on Ubuntu 18.04? wvdial is a versatile utility that simplifies the process of connecting to the internet via a modem. Although newer network managers are available, wvdial remains a preferred choice for many users who require a reliable, command-line interface for their 3G/4G modem connections. Ubuntu 18.04, while powerful and user-friendly, may not include all the necess...

In this tutorial, How to installing and configuring USB 3G/4G Data on CENTOS /RHEL. INSTALLING AND CONFIGURING USB 3G DATA ON CENTOS/RHEL To install wvdial usb_modeswitch usb_modeswitch packages for USB 3G modem. $ sudo yum install wvdial usb_modeswitch-data usb_modeswitch To check log $ dmesg | grep tty Plug and connected and detected for USB 3G modem on CENTOS/RHEL. To configure wvdial $ vi /etc/wvdial.conf  The content wvdial file as below [Dialer 3gviettel] Init1 = ATZ Init2 = ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0 Init3 = AT+CGDCONT=1,"IP","e-internet" Stupid Mode = 1 Modem Type = Analog Modem ISDN = 0 Phone = *99# Modem = /dev/ttyUSB0 New PPPD = yes Username = { } Password = { } Baud = 460800 Auto DNS = off check DNS =no Auto Reconnect = on Loading module USB 3G/4G modem $ modprobe usb_wwan usb-storage usbserial Running wvdial for 3gviettel $ wvdial 3gviettel & Yeh, You can add DNS in /etc/resolv.conf fi...