Doug’s Blog

Handily dispensing information to .00000001% of the world’s population

Archive for August, 2013

Bluetooth issue between Samsung Galaxy S4 and Mercedes

Tuesday, August 13th, 2013

So I got a nice sleek Samsung Galaxy S4 which is awesome! The Verizon store salesman tried to sell me on an iPhone but after I told him no thanks three times he finally let me see the Android options. I have nothing against the iPhone but just like the flexibility and options the Android gives me, plus even the sales guy admits the Galaxy is much faster than the iPhone.

But I digress… where was I? Oh, right — so the phone is AWESOME! Until I tried to pair the sonofabitch to my car, which is only 3 years old but could not do the pairing properly.

I would get the car to “see” the phone, and would enter in the PIN on the car, and the phone would pop-up and ask for the PIN, and the phone would say “paired”, but the car would eventually timeout and say it could not pair.

I tried all kinds of 4 digits PINs to see if that would make a difference, restarted the phone, removed the bluetooth entries and tried from scratch, but to no avail.

Finally I tried a single digit PIN and IT WORKED

So there you go, hope that helps someone, and now my new phone is back to AWESOME


SSH/SCP times out on cellular network

Wednesday, August 7th, 2013

I have a centos box I use when travelling and use an AT&T cellular USB modem on it for connectivity. I ran into an interesting problem when connecting in Las Vegas — I could get SSH sessions working fine up to a point, but when a lot of text was being outputted, the session would freeze and the connection would timeout.

This would happen when running “top”, or even if you started a “vi” session!

This looked like an issue with packet sizes, so I tried SCP’ing different file sizes and found that it would break at 1375 bytes when sending a file. After setting my MTU to 1370 the problem went away. The MTU was set to the default of 1500 prior.

So I must conclude that AT&T’s network in Las Vegas has a different network/routing setup than they use in other areas, because I have not see this problem before in California or a number of other states across the country.

For reference, the steps to fix this are:

ifconfig ppp0 mtu 1370

and then you can edit the config file, in my case “/etc/sysconfig/network-scripts/ifcfg-ppp0″ and add:


to the entries there.