/dev/ttyS0 is not a tty

Googl’ing around returned nothing helpful which is why I am posting this here.

I have a habit of  disabling unused peripherals when I setup a new box.  Since I rarely use Serial Ports, I disable them.  Well.. that was the problem.  The disabled serial port isn’t going to work very well for a serial connection.

Hope this saves someone some time.

The problem is the language that the internet speaks, is running out of unique names. Specifically, the IPv4 address space is running out of unassigned addresses. The simply version of why this is a problem is no new websites will be able to be online. It is a lot more complicated than that and will even impact users to a degree, but that is for a different article.

This is where the 600 days comes in. By the estimates of the people who are able to do estimates, the currently unused addresses will run out in about 600 days as of the beginning of 2010. As that day approaches, you can expect all sorts of shenanigans regarding pricing and allocation decisions. It will become much much more difficult and costly to setup your own website/service.

The good news is, there is a fix. The bad news is what I was saying in the beginning. It is going to be expensive as hell and it is going to impact a couple billion devices. The worst part is, you can’t even take steps to fix this yourself right now.

The answer is a new language. Internet Protocol Version 6 or IPv6. It solves the addressing problem for a VERY long time. The current version, IPv4, supports about 4.3 Billion addresses. This is represented by 32bits or 2^32nd. IPv6 supports 340,282,366,920,938,463,463,374,607,431,768,211,456 addresses which is 128 bits or 2^128th. This post does a good job of expanding on what this means.

Because this is a new language, this means all of the devices have to be taught to speak it.  In the vast majority of cases, this is software and could be done for free.  The problem is if you are the manufacturer of such a device, why would you provide a free upgrade, when you could sell a new device?  This is further complicated, by the fact that essentially no one supports IPv6.  The deep insides of the internet do, but the majority of the pieces that are exposed on the internet, do not.  The biggest hurdle is most ISPs (Comcast, ATT, Verizon, Charter, Cable Vision, etc) don’t support IPv6 for their users.  Even if you could go buy replacement devices or upgrades to your equipment to support IPv6, you still don’t have access to the IPv6 Internet.

During the period of overlap when not everything speaks IPv6, we will run into problems of sites only being accessible from v4 or v6.  As time progresses that will go from overwhelmingly v4 to primarily v6 and this transition will take a very long time.  The general masses are going to learn more about networking than they wanted to know out of necessity.  Where did I put that number to tech support?

TL;DR; We have 600 days to make the Internet6 accessible.  After that, things start becoming REAL complicated, real quick.

Note:  This article is meant to build awareness not be complete or thurough.  There are large gloss-overs, simplifications and omissions to keep this from being a book.

I am hoping to put together a post about my journey, but I suspect it will end up like the post I have been working on for my Vyatta router build.

I digress.  Good article here on how to dis/enable IP Forwarding, but more importantly for my memory it also has the sysctl syntax which I forget on a regular basis.

Check if IP Forwarding is enabled

We have to query the sysctl kernel value net.ipv4.ip_forward to see if forwarding is enabled or not:
Using sysctl:

sysctl net.ipv4.ip_forward
net.ipv4.ip_forward = 0

or just checking out the value in the /proc system:


cat /proc/sys/net/ipv4/ip_forward
0

As we can see in both the above examples this was disabled (as show by the value 0).
Enable IP Forwarding on the fly
As with any sysctl kernel parameters we can change the value of net.ipv4.ip_forward on the fly (without rebooting the system):

sysctl -w net.ipv4.ip_forward=1

or

echo 1 > /proc/sys/net/ipv4/ip_forward

the setting is changed instantly; the result will not be preserved after rebooting the system.
Permanent setting using /etc/sysctl.conf
If we want to make this configuration permanent the best way to do it is using the file /etc/sysctl.conf where we can add a line containing net.ipv4.ip_forward = 1

/etc/sysctl.conf:
net.ipv4.ip_forward = 1

if you already have an entry net.ipv4.ip_forward with the value 0 you can change that 1.
To enable the changes made in sysctl.conf you will need to run the command:

sysctl -p /etc/sysctl.conf


There is some good stuff down in the comments too.
Thanks MDLog.

Thanks Lnx2.

I have made some slight modifications and formatting to the original steps based on what I found to work.

There are two methods.  1 is to not use a partition table and write the file system directly to the device.  Method two is more traditional.

1. Method (/dev/sdX is your USB flash drive) :

A) Create a filesystem n the whole device without a partition table.(saves some space, and you don’t have to worry about the MBR)

sudo mkdosfs -I -v -n Ubuntu -F 32 /dev/sdX

B) Create “volume boot record” and the file ldlinux.sys using this command:

sudo syslinux /dev/sdX”

C) Mount the USB drive and the iso image file.

sudo mount -o loop /path/to/iso /mount/point
sudo mount /dev/sdX /mount/point

D) Copy all the files in the iso to the USB drive:

sudo cp -P --preserve=all -R /path/to/iso/* /path/to/iso/.* /usb/mount/point/

E) Rename the isolinux directory to syslinux and the isolinux/isolinux.cfg to syslinux/syslinux.cfg

sudo mv isolinux syslinux
sudo mv syslinux/isolinux.cfg syslinux/syslinux.cfg

F) reboot

2. Method (/dev/sdX is your USB flash drive):

A) Create a partition:

sudo parted /dev/sdX

In parted

mkpart primary 0% 100%
quit

B) Create a filesystem on the firstpartition

sudo mkdosfs -v -n Ubuntu -F 32 /dev/sdX1

C) Overwrite the MBR.

sudo dd if=/usr/lib/syslinux/mbr.bin of=/dev/sdX count=1

D) Create “volume boot record” and the file ldlinux.sys using this command:

sudo syslinux /dev/sdX1

E) mount the USB drive and the iso image file.

sudo mount -o loop /path/to/iso /mount/point
sudo mount /dev/sdX /mount/point

F)copy all the files in the iso to the USB drive:

sudo cp -P --preserve=all -R /path/to/iso/* /path/to/iso/.* /usb/mount/point/

F) rename the isolinux directory to syslinux and the isolinux/isolinux.cfg to syslinux/syslinux.cfg

sudo mv isolinux syslinux
sudo mv syslinux/isolinux.cfg syslinux/syslinux.cfg

G) reboot

Same as last time.  Power-off the VM, close it in VMWare application, and edit the .vmx file.

Add the following:

MemTrimRate = "0"
mainMem.useNamedFile=false
sched.mem.pshare.enable = "FALSE"
prefvmx.useRecommendedLockedMemSize = "TRUE"

I haven’t tested it much so far, but I am willing to give anything a try to improve the performance of the VM.

This is also  a common problem with a very simple fix.  Apparently, sometime in the past, I added a line to my /etc/vmware/config file to problem fix or enable some other feature.  This line and Unity just don’t mix.

The fix, per this thread and ultimately this blog post, is to remove the following line from your /etc/vmware/config file.

xkeymap.nokeycodeMap = true

Keep reading the VMWare Communities post for additional details if you added that line to address some key mapping issues.

It turns out that this is a known problem in the ntfs-3g driver and is being ‘worked on’.  I say ‘worked on’ cause the problem has apparently been around for a long time.  So long in fact, that it has made it to the FAQ on the ntfs-3g.org website here.  With all of that said, the solution is to simply add a line to your .vmx file.  Note:  This is a per-VM setting, so you will have to do it on all of them.

Edit your .vmx file and add the following.

mainMem.useNamedFile=FALSE

Do note as the state on the website that your /tmp dir must be on a non-ntfs-3g partition or else you could cause additional performance issues.