X-ISP and Maintaining Multiple Account Records
Connecting your Linux box to a PPP server can be a frustrating task, especially if you are not familiar with the scripting requirements, authentication modes or network settings your ISP expects you to use. X-ISP, a program written by Dimitrios P. Bouras (email@example.com), takes what could be a complex task and simplifies it with a clean, effective GUI front end.
What makes X-ISP such a great piece of software? First, it is a user-friendly X-based front end to PPP/CHAT. Second, X-ISP provides a dialer, xispdial, and a stripped-down terminal, xispterm, which help work out some of the difficulty in establishing a connection. By using PPP/CHAT, X-ISP leaves most of the work to the operating system, while also giving experienced users the freedom to hack familiar connection scripts for any special needs.
X-ISP can be found at http://users.hol.gr/~dbouras/. To run X-ISP, you need to have X11R6, Xforms-0.88 and ppp-2.2.0f, and your modem must be set to verbose mode so that X-ISP can pick up connection status correctly. The home page provides comprehensive information and screen shots of the configuration and main screens. Once downloaded, the installation README gives clear instructions on how to compile X-ISP on a variety of systems.
X-ISP adds two helper modules called by pppd (see Figure 1). The first, xispdial, takes care of the dialing. xispdial sits between pppd and chat and is used by X-ISP to start the connection. xispdial reads an environment file residing in the user's directory. After getting the information for the ISP selected, it calls chat to make the connection. Once connected, control of the modem is turned over to the second module, xispterm. This terminal program allows the user to log in to the system manually, or in the case that ip-up/ip-down scripts exist, xispterm runs those scripts. X-ISP also runs user-specific scripts, .xisp-up/.xisp-down, which reside in the user's directory and provide increased versatility.
A named pipe sends information from pppd, chat, xispdial and xispterm to the terminal window in X-ISP. The pipe gives immediate feedback as to system and connection status. The terminal window provides a clean view into the connection sequence and invaluable information for tracking down any connection errors.
The user interface provides all actions through five buttons, three pull-down menus and a drop list for selecting which account to activate. The first step is setting up an account through the Options menu.
First, open the “Account Information” item. Enter the name of the account to add, then enter the phone number, user name and password. You will also need to know which authentication protocol your ISP uses. (See Figure 2.)
The next item, “Dialing and Login”, has you set the login and connect environment. Set the number of retries, connect notification, ISP callback and login setting. For manual login, X-ISP will start xispterm, or if you know the sequence, you can put together an automated login script and send user name, password and any initialization commands to the remote host. (See Figure 3.) X-ISP will use the connection script for automatic login or ISP call-back. For PAP or PAP/CHAP-Secrets authentication, the script will be ignored.
“Communication Options” allows you to control settings for the modem, baud rate, flow control, initialization and reset strings.
The final item, “TCP/IP Options”, sets up Network Addressing. The most notable point here is the “Support for ip-up/ip-down” scripts. If set to “yes”, the DNS addressing can be set for each account, providing great flexibility when maintaining multiple accounts by dynamically updating the /etc/resolv.conf file. (See Figure 4.) When using ip-up/ip-down, X-ISP sends the ipparam option to pppd, which passes a string to ip-up/ip-down containing the pipe name for X-ISP, the description set in Account Information, and if set, the DNS addresses specified. X-ISP will also display any information from ip-up/ip-down on the terminal window via the named pipe.
The next menu choice is Logging. If you are located in Europe, you will get the most advantage of this feature as the telephone companies (TelCo) listed are applicable only there. By selecting the appropriate TelCo and zone, X-ISP will keep track of on-line cost.
The Statistics item displays usage data in a window with a text summary and a bar graph.
The last item is the Help menu. Any issues you come across will probably be addressed in this very thorough help file. The “about” screen displays the version number and how to get in touch with the author.
Once your account is set up, you are ready to connect. First, check the following to be sure the rest of the system is in order:
Set pppd for all users (i.e., other than just root):
chmod u+s /usr/sbin/pppd
Check the permissions on all X-ISP modules (xispdial, xispterm ...) so that group root can execute them (this should be done by the install script):
Add any users who will use X-ISP to the dialout or root group for Debian or Red Hat releases, respectively.
Now, to connect, click on the “Connect” button in the main window of X-ISP. You should see the connection feedback in the small terminal window to the right. (See Figure 5.) Once the connection is established, the status windows will report the assigned IP address, modem connect status, connection speed and time since connected. The status is updated every 15 seconds, so if your connection is dropped, a maximum latency of 15 seconds will pass before X-ISP recognizes the dead connection and allows you to reconnect.
Hopefully, everything now works correctly. If there is a problem, the terminal window in X-ISP should give you an indication of where to look.
Practical Task Scheduling Deployment
July 20, 2016 12:00 pm CDT
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
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