Log Conversation Only with TCPDUMP

Not exactly the conversation view from Wireshark, but it's a relatively clean and readable output showing the source, destination IP addresses, and ports.

tcpdump -q -i <interface>

Add the '-t' switch to remove the time stamp as well

Posted on March 27, 2015 and filed under Tips'n Tricks.

OS X Yosemite DHCP Server

This week I re-installed my Mac Mini server at home. It still ran Snow Leopard, and it was time to start with a clean slate. So after a couple of hours of pondering if I had forgotten to backup something, I started with a clean install of OS X Yosemite (10.10).

Everything went smooth, until I started using the DHCP service that comes with the Server App add-on.

My server uses 802.1q (VLAN-tagging) to connect several different VLAN's which I feed into several Virtual Machines. So I also use several DHCP Scopes for those segments.
The IP addresses for these scopes are all in the 192.168-range (class C subnets), so when I created the scopes I had to go through a simple wizard in the Server App. I just had to fill-in the blanks (very user friendly), and OS X did the rest.

Upon testing I ran into the weirdest behaviour on my network. Getting connectivity with a device took a very long time, and when the device got an IP address, it was from a different network (???)> So it couldn't communicate across the network.

At first I began to wonder if I had mixed up the VLAN names and tags, but those were correct. After an hour of troubleshooting (more and more DHCP clients were failing in the network), I found the problem;

When you create a scope Apple will assign a default subnet mask ( I guess I should have seen it, but I didn't.

After I changed the subnet mask in the DHCP scopes everything went back to normal.

Lesson learned: Don't rely on wizards and other user-friendly stuff.

Posted on December 31, 2014 and filed under Apple, Annoying, Tips'n Tricks.

PlayStation Network Down and How To Get It Working Again

This Christmas (2014), several gaming networks were attacked by a DDoS. One of those networks being the Playstation Network (PSN). This resulted in severe downtime during the holiday season. Sony is/was working hard to resolve this and service is being restored all around the world. Except for me (and probably several thousand other gamers). As of this morning (December 29th, 2014) I was unable to log on to PSN. All I got was one of the much telling error codes:



Someone on the Interwebs mentioned that a change in the MTU size might help. The MTU size is the maximum transfer unit on a network, which is normally at 1500 (bytes) for regular network clients. In some case it's preferable to adjust this size (I won't get into details).

In the case of PSN being down, an adjustment from 1500 (the default) to 1473 seems to do the trick at the moment. Not sure if it wil hold up in the (near) future, but at least you can get online to play on your new Playstation 4 or with the new game you got for Christmas.

  1. Go to the “Settings” menu.
  2. Go to “Network” sub-menu.
  3. Go to "Set Up Internet Connection".
  4. Choose your media (WiFi or LAN).
  5. Choose “Custom.”
  6. Leave everything as default except MTU (Manual).
  7. Change MTU settings to “1473”.
  8. Save your changes.
  9. Test the Internet connection.

And if you are more of a visual kinda person:

Everything should work now. If not, you may try a reboot.

Lowering the MTU size means that smaller packets are being send over the network (max. 1473 bytes instead of 1500 byte packets) , this is not a bad thing, but might lead to some performance problems in some cases. Just remember that you changed this setting. You want to (or have to) change this back to the default (1500) in the future.

I do not know if this works for other gaming devices. You may try at your own risk (and leave the results in the comments if you'd like).

UPDATE: As of this morning I was able to sign in to PSN with an MTU of 1500 (access the Playstation Store etc.), but I was unable to play online games (Battlefield 4). Changing the MTU back to 1473 fixed that (again).

UPDATE 2: As of this morning (31 december) I can also connect to PSN with an MTU of 1500, so everything is back to normal.

Posted on December 29, 2014 and filed under Annoying, Tips'n Tricks, Gaming.

Entering The World Of Android Based Media Players

This is gonna be a good one. An Apple Fanboy Going Android..... WTF!?

Yep, it's true to some extent. The reason for letting myself into the Android world is a media player one. Up till recent I was quite happy with my Popcorn Hour A-110, which I bought 6-7 years ago. Happiness started to fade when transfer speeds and connections to the device started to fail. Networking was never its strongest part, even though it had a 100mbps interface. For some reason it never got above the 10Mbps speeds. Had something to do with the processing priority of the device.

Anyway, lately, larger FTP transfers failed for whatever reason, and using SAMBA transfers.... well, don't get me started on that file transfer protocol. Sending communications by pigeon-mail is faster. And since streaming over the network was not an option for the larger (far less compressed) x264 encoded movies or TV shows, I started to look for an alternative.

The alternative should be able to connect to remote media sources, and have enough processing power for the network adapter to get decent a throughput. Also some additional multimedia features were on the 'very-nice-to-have' list. These features included (but were not limited to);

  • stream various content from the web
  • not limited to just video
  • easily modifiable (apps etc.)
  • prepared for the future (4k video?)
  • xbmc (or something alike)

With this list of requirements, there were about a gazillion candidates, because every player out there tends to support this. So I needed to narrow down the candidates. I did exclude the current Popcorn Hour because of the physical size of there latest models.

Posted on December 27, 2014 and filed under Gadgets, Hardware, Personal, Review, Tips'n Tricks, Video.

OSX 10.10 (Yosemite) and Audio Out Changes

Yesterday I ran into a new Yosemite feature that annoyed me a bit. After changing the input on my Dell 27" display from DisplayPort to HDMI, the screen turned black on my 27" iMac, and audio stopped. Forcing a reboot (holding the power button for >4 seconds) was needed to get the iMac's display back.

But from that point on, the audio was greyed-out in the menu bar. Changing the volume on the (Apple) keyboard gave a disabled icon on screen. Also, no audio was playing over my external speakers.

My first thoughts were that the earlier crash had corrupted something on my system, so I did an additional reboot. Nothing. After that a PRAM reset (power off, power-on and hold command-option-P-R until you have heard two start-up 'boings'). The start-up sounds were there, so the actual audio hardware was just fine.

When the desktop loaded still no audio control, until I unplugged my DisplayPort connector on the Dell 27" monitor. Audio (controls) came back instantaneous.

So, with DisplayPort connected to the external monitor: no audio (controls), and without the DisplayPort: audio (controls).

Turns out that with Yosemite, the audio is channelled BY DEFAULT over a DisplayPort connection (to a external monitor). In my case, the Dell also has an audio out connector, and I guess that is 'advertised' over the DisplayPort.

Changing the default behaviour is done in the System Preferences -> Sound

The first image shows the default (at least in my case). Changing the settings to the second image gave me back the audio and volume control.

I have no idea if this was also possible with Mavericks (or even earlier versions of OSX), but it's definitely a (default) feature that annoyes the hell out of me.

Even though I tackeled the audio problem, the issue with loosing the display when I change the video input on the external monitor still remains. But only if the desktop is extended to the second screen. It doesn't occur when the screen is mirrored.

Posted on November 18, 2014 and filed under Annoying, Apple, Operating Systems, Tips'n Tricks.