Latest Updates: bsd

  • SSH Client: Saving Server Configuration (Alias, Port, Username)

    14:46 on August 2, 2009 | 0 Comments Tweet This! | Digg This!
    Tags: bsd, , ,

    There may be occasions where you want to connect to a host with a long host name, for example ssh servername.example.com – now it’s not massive, but it’s not as quick as ssh servername

    If you’ve been following droptips.com, you’ll have noticed my other post about setting the port number in the SSH config file (~/.ssh/config for individual users) – you can also use this config file to connect to shortened hostnames (aliases).

    So, if you want to be able to ssh into servername.example.com but just doing ssh servername, you would add the following to the ~/.ssh/config file:

    Host servername
  HostName servername.example.com

    Now that’s great if you login to your local machine with the same username as the remote server, but what if it isn’t?  You’d have to do ssh remoteusername@servername but we can also get around this by adding User username to the host section:

    Host servername
  HostName servername.example.com
  User remoteusername

    You can also tie this into having the port number as per my other post like so:

    Host servername
  HostName servername.example.com
  User remoteusername
  Port 1234

    Once you’ve done this, whatever you put on the Host line, will work by just doing the following with whatever options the configuration file says:

    ssh host

    Hopefully this will allow you to speed up connecting to servers you connect to a lot!

     

  • SSH Client: Automatically Connect to a Servers’ Non-Standard Port

    10:18 on August 2, 2009 | 0 Comments Tweet This! | Digg This!
    Tags: bsd, , ,

    If you run an SSH server, or many SSH servers, then you may have set the SSH daemon to run on a non-standard port. SSH normally listens on port 22, but with the large amount of script/bot attacks now on this port, attempting random logins, changing it to something different is a quick way to stop the majority of these automated attacks.  I’ve detailed this in another post here.

    Once you’ve done this, though, you probably get bored with having to specify the port every time you connect by typing ssh -p 1234 hostname or scp -P 1234 hostname (where 1234 is the port SSH is running on hostname) – I know I do!

    You can get around this problem, by using the ~/.ssh/config file (config in the .ssh directory in your home directory).

    You can add multiple hosts to this file, along with their port, so you can simply ssh hostname and it’ll connect  using whatever port is set in that file.

    The entry you need to add is:

    Host host.example.org
  Port 1234

    Where host.example.org is the hostname you SSH too (if you SSH to an IP address, then this will need to be set here) and Port 1234 is the port number SSH is running on hostname.

    Once this is done, you’ll be able to:

    ssh host.example.org

    … and it’ll know that you need to connect on the port set in the file.

    You can add multiple hosts to this file, if you access multiple SSH servers:

    Host host.example.org
  Port 1234
    Host host2.example.com
  Port 4567

    Give it a try – it’s certainly saved me some time!

    You may also want to checkout another post on droptips.com with further options for the ~/.ssh/config file:  http://droptips.com/ssh-client-saving-server-configuration-alias-port-username

     

  • Quick command to check the status of a URL (Linux, BSD, OS X)

    22:54 on July 28, 2009 | 0 Comments Tweet This! | Digg This!
    Tags: bsd, , ,

    There may be times when you just want to do a quick check to see whether a web site is up, and/or what status message the web server is showing. This won’t actually show you if the page it served up is correct or not, purely the web server status code on whether or not it served something/anything/nothing!

    There are lots of status codes for web servers, and they are detailed here: http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html

    So, to be able to see the status message, and to check if a host is up or not, we can use the curl command.  curl is installed by default on OS X, but you may need to install it on your Linux distribution or BSD installation.

    So, to do a quick check from a command line:

    curl -Is http://droptips.com | head -n 1

    And you’ll get something back similar to:

    HTTP/1.1 200 OK

    Status code 200 is “OK”.

    HTTP/1.1 200 OK

    As another example, to show you how this will display different status codes, you’ll notice that if you visit: http://www.droptips.com you are redirected to http://droptips.com, purely because I prefer not to have www in the URL.  I do this by implementing a 301 (Permanently moved) from within Apache for any client going to http://www.droptips.com:

    $ curl -Is http://www.droptips.com | head -n 1
    HTTP/1.1 301 Moved Permanently

    As you can see, the web server returned a 301, and this is shown.

    curl can also take full URLs, so you can check whether or not a particular page/path is being served or not:

    curl -Is http://droptips.com/tag/tips/ | head -n1
HTTP/1.1 200 OK

    So if you want to see if that new redirect is working, or just to see if your web server is up and serving requests, give curl a go!  This is just a basic overview of one thing you can do with curl - it’s a very flexible command, and can be used in a number of scenarios, some of which I will post about in the future.

     

← Newer Tips |   Older Tips →