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  • Testing your Mail Server

    Testing your Mail Server

    Telnet to your smtp server using the following:
    "telnet example.com 25". The number "25" is the default portnumber for outging mail, defined by IANA.
    Substitute the address with your own address or ip number.
    Even though this might very well be possible to do on your ISP mail server, dont!!
    This will give you the SMTP server banner. I hope this has been changed or spoofed to protect from banner grabbing.
    In my example, it gives me "220 example.com...
    See more | Go to post

  • Knowing your System Performance and State

    Knowing your System Performance and State

    Here are a few command line tools that will help you estimate your system usage and performance.
    There is a lot more information on this in the man pages so take a look there also. If you dont know your average system load you will not be able to determine if the load is in a peaking state or if the host is able to handle more load.
    Note that some commands might require installation of a few packages.

    Below gives a nice simple performance view of a HDU. Ofcourse running...
    See more | Go to post

  • Browsing your Hardware in Linux

    Browsing your Hardware in Linux

    Sometimes it can be quite a challenge to find out what hardware you have but it is actually quite easy.
    Here are a few commands and some sample output for you.

    USB devices are usually easy to identify because you can just pick them up and look at them.
    Below will help you out with the few that just say NoName on it. Often those noname ones are the same as the named ones just with another wrapping. Below display a list of detected USB devices.

    # lsusb
    Bus...
    See more | Go to post

  • Keeping an Eye on Logfiles

    Keeping an Eye on Logfiles

    If you want to watch a log file and have it update when ever new content is added the "tail" command is an easy on-the-fly tool to use.
    Ofcourse for long term use other implementations of log file analyzers or syslog services would be better.
    Here is a short example and some sample output showing a failed root login attempt.

    # tail -n 20 -f -s 5 /var/log/auth.log
    Feb 17 04:11:09 testbox login[4822]: pam_unix(login:auth): authentication failure; logname=LOGIN...
    See more | Go to post

  • Learn which Libraries Programs Call

    Learn which Libraries Programs Call

    Sometimes it comes in handy to know what libraries and what versions of those libraries some software is depending on.
    This is quite easy and is done with the "ldd" command.

    Here are the dependencies that the "ls" command has. Remark that you have to use the absolute path as ldd does not support the use of the search path stated in the environment variable PATH.

    # ldd /bin/ls
    linux-gate.so.1 => (0xb7fd4000)
    librt.so.1 => /lib/i686/cmov/librt.so.1...
    See more | Go to post
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  • Testing your Mail Server
    by Resheph
    Telnet to your smtp server using the following:
    "telnet example.com 25". The number "25" is the default portnumber for outging mail, defined by IANA.
    Substitute the address with your own address or ip number.
    Even though this might very well be possible to do on your ISP mail server, dont!!
    This will give you the SMTP server banner. I hope this has been changed or spoofed to protect from banner grabbing.
    In my example, it gives me "220 example.com...
    08-06-2016, 10:38 PM
  • Knowing your System Performance and State
    by Resheph
    Here are a few command line tools that will help you estimate your system usage and performance.
    There is a lot more information on this in the man pages so take a look there also. If you dont know your average system load you will not be able to determine if the load is in a peaking state or if the host is able to handle more load.
    Note that some commands might require installation of a few packages.

    Below gives a nice simple performance view of a HDU. Ofcourse running...
    08-06-2016, 10:35 PM
  • Browsing your Hardware in Linux
    by Resheph
    Sometimes it can be quite a challenge to find out what hardware you have but it is actually quite easy.
    Here are a few commands and some sample output for you.

    USB devices are usually easy to identify because you can just pick them up and look at them.
    Below will help you out with the few that just say NoName on it. Often those noname ones are the same as the named ones just with another wrapping. Below display a list of detected USB devices.

    # lsusb
    Bus...
    08-06-2016, 10:34 PM
  • Keeping an Eye on Logfiles
    by Resheph
    If you want to watch a log file and have it update when ever new content is added the "tail" command is an easy on-the-fly tool to use.
    Ofcourse for long term use other implementations of log file analyzers or syslog services would be better.
    Here is a short example and some sample output showing a failed root login attempt.

    # tail -n 20 -f -s 5 /var/log/auth.log
    Feb 17 04:11:09 testbox login[4822]: pam_unix(login:auth): authentication failure; logname=LOGIN...
    08-06-2016, 10:31 PM
  • Learn which Libraries Programs Call
    by Resheph
    Sometimes it comes in handy to know what libraries and what versions of those libraries some software is depending on.
    This is quite easy and is done with the "ldd" command.

    Here are the dependencies that the "ls" command has. Remark that you have to use the absolute path as ldd does not support the use of the search path stated in the environment variable PATH.

    # ldd /bin/ls
    linux-gate.so.1 => (0xb7fd4000)
    librt.so.1 => /lib/i686/cmov/librt.so.1...
    08-06-2016, 10:29 PM
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