Objective-C modal Window using sheets and Panels

Adding a modal sheet to a window in objective-C isn’t highly complicated however there are a number of issues to watch for that can leave you scratching your head. Most of the examples I’ve found on the internet point to an older useModal: (*window) function which is deprecated. From what i’ve read, the correct manner for using a modal dialog is to display a sheet that scrolls down from the menu bar and takes modal control. There are numerous examples of this in System Preferences:

Implementing this in an application coded with objective-C isn’t relatively complicated  however missing a particular setting can leave you with numerous errors or causing the application to fall back to the debugger.

Cheap disks

The flooding in Thailand has been pretty horrible for a number of reasons (mainly deaths and loss of homes/possessions), but its also having a knock on effect in the area of hard drive manufacturers.

http://www.guardian.co.uk/technology/2011/oct/25/thailand-floods-hard-drive-shortage

This has had a further effect of having all of the resellers increase the price of hard disks quite significantly in some cases doubling the price in a couple of weeks. Quickly looking at a few places in the UK (at the current date 1st Nov ’11) you can see that the average 2Tb hard disk is currently priced at around £130

Cocoa libssh2 wrapper

I’ve modified a simple wrapper for the libssh2 library that now has the following functionality:

  • Code moved to separate classes to allow reusability
  • Multiple sessions to different servers can be achieved with a few lines of code
  • A Session can be passed to the operator class allowing operations (commands sent to it), more will be added
At the current time it connects fine to OSX and Linux sshd however I can’t connect to ESXi even with the correct password it reports incorrect, However I think I Can resolve this shortly.
Original wrapper (designed for iOS) can be found from http://lukehagan.com/ in his Git Repo.
Download here: SSH Wrapper

SSH with Cocoa (Xcode and libssh2)

I fought with this about a year ago, and for some strange reason never managed to get things to compile or link. I chalk this down now to my lack of understanding with Objective-C/linking concepts. However it turns out that it is relatively simple (ensure you have Xcode 4 installed before trying).

  1. Point browser to http://www.libssh2.org/ and download the latest snapshot to a temporary location.
  2. Open a terminal window and navigate to the directory containing the the source files and run the following:
    dan$ ./configure
  3. This will output numerous content to the terminal window, present a summary of the configuration options and create a header file needed for compilation. (Running make / make install is NOT required).
  4. Open Xcode and create a new Xcode project, which should be a (Mac OS X -> Framework & Library -> C/C++ Library) and give it a Product Name (e.g. libssh2) and ensure that the type is Static then click create.
  5. Xcode will open with an empty project displaying the Build Settings. At this point we can start adding the files that are part of the libssh2 source tree.

Getting files through a terminal window

This is a technique I had to use numerous times for a previous job where I would need to transfer files from servers that could not be connected to directly. In the majority of companies there will be numerous networks, where “jump boxes” are required to get across various networks and get to the server in question.

The usual approach of moving files to servers would be through a variety of means (FTP/SCP/NFS/CIFS etc.), however in the case of numerous jump boxes and networks would mean that having to transfer the file between each jump/network. It is possible to use copy and paste however this would only work in the case of text files, trying to display or copy binary data can cause all manner of issue and really mess up your terminal window. So for me the best solution is to UUEncode the binary data into ansi text which can be safely copied out of the terminal window, pasted into a file on your local machine and UUDecoded back to binary data again.

To do this simply UUEncode a file, and the output will be presented to STDOUT i.e. the terminal window.

$ uuencode test.rpm test.rpm

Note: the double typing of the name is required as the first argument is the file to uuencode, whilst the second argument is the name of the file that will be outputted. The output will be presented to STDOUT as shown in an example :

begin 644 test.rpm
M"GP]+2TM+2TM+2T]6R!796(@=G5L;F5R86)I;&ET:65S('1O(&=A:6X@86-C
M97-S('1O('1H92!S>7-T96T@73TM+2TM+2TM+2T]?`I\/2TM+2TM+2TM+2TM

The next step is simply to copy everything from the word “begin” to the word “end” out from the terminal window and then paste it into a text editor of your choice on your local machine under a temporary name. This will then need opening with uudecode, which will then process the text and spit out the file under the filename specified with the encoder.

$ uudecode temporary.uua

In the same location will be the decoded file.

ESXi v4.1 SFTP access

[UPDATE]

This is a 32bit binary, which I think needs some pretty old kernel version. Hence it only works on 4.0, I will try and get an updated release for 4,1 (*note) ESXi 5 comes with sftp-server already.

 

I came across something interesting while fiddling earlier, after spending about 2 hours building a static release of openssh server that was going to replace dropbear. I’d gotten to a point where I could build a i386 release of the binaries with no random library requirements and sshd would start and listen on a port defined in /etc/ssh/sshd_config. unfortunately starting ssh in debug mode allowed me to see numerous glibc errors during connections and explain why I couldn’t connect. At this point I don’t think there is any real way of replacing dropbear with a complete openssh solution even statically linking. Even testing the openssh sftp binary that had been compiled showed that it wasn’t coping with a system call not returning UIDs correctly meaning that it would report a FATAL error and close continually.

Given openssh wasn’t going to be replaced I researched about dropbear and if there was a newer version perhaps with sftp, unfortunately not. Eventually I came across notes on a blog mentioning that dropbear “supports” openssh sftp. After restoring ESXi back to its default filesystem settings (ssh enabled) it appears the attempting to sftp to esxi returns the following error.

ash: /sbin/sftp-server: not found
Connection closed

After compiling a slightly older version of openssh (static) I found a release of sftp-server that will once placed in /sbin on ESXi allows full usage of sftp (including sshfs mounting) binary below.

sftp-server.tar.gz

 

 

 

 

 

 

 

File access in ESXi 4.1 (nfs and tcp)

I’ve had numerous occasions were i’ve needed to upload files to the actual file systems on an esxi system, the only ‘proper’ method is using the abysmal virtual infrastructure client and working mainly on a mac means I need to use VMware Fusion for windows to run the client to connect to the server (overkill). So it’s possible to enable ssh access to the server using the tech support menu, which allows access to the underlying hypervisor and it’s file systems and therefore it’s possible to scp files to the filesystems again this is quite slow and overkill due to the encryption being used. Also due to dropbear being used for the ssh it doesn’t use sftp, which means that you can’t mount the filesystems ala. FUSE and sshfs.

I should say at this point, the goal of all this was to allow me to keep all my ISOs on one server and be able to access them from everywhere also, I wanted a PXE server to be able to access the ISOs and loopback mount them and then present the contents via NFS to the installers started by PXE.

So looking around I found some ftp binaries that should work on ESXi, given that the console access for ESXi is done with busybox there is no file command to determine what binary type the files are so I was unaware of what binaries I could run inside ESXi. This all worked fine following the instructions located on the vm-help.com website here however a few of the instructions are a little bit incorrect such as the path to tcpd is incorrect in inetd, however i’ll leave you to fix that. So on the PXE server using FUSE again and curlftpfs to mount the filesystem and this revealed a glaring bug as soon as I loop back mounted the first ISO. Unfortunately the problem lies in the fact that curlftpfs will use memory to store the file as it downloads it for access by FUSE, so trying to open a 4GB DVD ISO quickly exhausted my PXE servers memory and then it became unresponsive, great.

Further research turned up a blog post about some guy trying to use unfs to enable nfs sharing between two ESXi boxes, more specifically it was mentioned that linux binaries would work fine in the ESXi service console. One thing that was slightly confusing was that ESXi is x86_64 (64bit) however binaries that you need for the service console have to be 32bit otherwise you’ll get a confusing error that the binaries can’t be found when you try and run them due to busybox’s odd handling of errors. I present below the binaries required for nfs in ESXi :-

nfs binaries for x86

These are pretty easy to use, scp the file over to ESXi and untar it in /tmp al that’s left is to place the files in /tmp/sbin into /sbin and the files in /tmp/etc into /etc. The /etc/exports contains one entry to give access to /vmfs/volumes, which means that accessing the nfs share will give you the UUID paths for the disks containing VM’s and ISOs. To start the nfs server, start portmap first and then start unfsd which should be started the following way (unfsd -d &), this is due to unfsd not being able to disconnect from console on start up (something to do with busybox I assume).

One final note, is that once another machine connect to the nfs share portmap will go start using 50%-70% cpu and will need stopping and starting for other nfs clients. I’m still looking into this, however having a cron job to restart the process every few minutes should do the job.

ESX 4.1 USB install and Password complexity changes

As a point release i’m not sure why VMware decided to completely change the layout of files on the CD ISO along with change various system files, however they have. I suppose one change is beneficial as it improves the method for creating a USB stick which for previous versions of ESXi is documented here. They have also changed console access and ssh access to the hypervisor, which now can be enabled from the orange console screen under TSM (technical support mode) settings.

Writing to a USB stick:

Now the iso contains a simple file called imagedd.bz2 that is found in the root of the iso, which just need bunzip to decompress it and the dd’ing to a USB stick as documented before.

Password complexity:

At the moment there is nothing about this on the internet so it was a case of going through a few files to find it, but previously /etc/pam.d/common-password contained all of the password complexity requirements as documented on the VMware KB. However now all of the password requirements are located in the file /etc/pam.d/system-auth, so this file will need editing if you don’t want insane password requirements for all users.

Further Xcode – HelloWorld

The inevitable HelloWorld application is a staple in learning a programming language, and provides the learner with the feeling of accomplishment as their first program speaks back to them… or something. Either way, this example will present us with a basic framework which we can use to build upon.

To break it down this example consists of,

– Creating a blank project in Xcode

– Using the default Delegate class and adding our own method (interface)

– Linking the GUI to our class

– Adding code to our method (implementation)

– Drinking tea