Are backpack nets an effective deterrent when going to rougher parts of the world?

I spent the first half of thus year in southeast Asia (Malaysia, Indonesia, Myanmar, Laos, Thailand, Vietnam, Cambodia.)

First of all, I wouldn't consider this a "rough" part of the world. True, cost of living is much less than the US/Europe, and pay is consequently less. But, generally speaking, the most danger of theft you'll run into while staying in hostels is from other foreigners.

(This is in contrast to South America. I know a guy who had his entire 70 L backpack stolen in Colombia. In Southeast Asia, your greatest risk in terms of your backpack will be someone unzipping an unsecured compartment and helping themselves to the contents. Once you're inside a country (and not transiting), this will most commonly happen when you leave your pack at a hostel, the culprit will most likely be one of your roommates, and their target of choice will be electronics, passports, money, etc.)

That being said, you'll want to secure your backpack whenever it is out of your direct supervision, namely on transport. I have heard about people rifling through unsecured luggage during rest stops on long bus rides, but as usual it's luck-of-the-draw -- it never happened to me or anyone I met, but that's not to say it doesn't happen at all.

I personally have an airporter backpack cover that I stuff my backpack into. It's really just a glorified duffel bag. It serves several purposes:

1. it has a single zipper that I can lock unlike my six zips and drawstrings and buckles on my pack
2. it provides some measure of protection against rough handling in airports which is important for buckles and straps; and
3. it is not a bright color nor interesting looking and it disguises its contents handily. It also has a useful handle; when staying at a hostel in Laos that had pitiful security (locks? why would you want locks on doors? silly tourists...), I used a bike chain to secure the airporter to my bed.

A net on the other hand still allows someone to unzip a compartment and rifle through it. I personally have never seen one in the wild.

Other solutions I've seen:

• One backpacker I met used fishing twine to sew up all but one of the zips on his backpack, leaving only a single compartment entrance which he then locked. This had the unfortunate side effect of making those other compartment openings useless.
• In airports, I commonly see backpackers use the plastic wrap machines to secure straps etc. This wont help you for land travel since these plastic wrap machines appear to be native to airports. You'll be doing a lot more land travel (buses, trains, hitchhiking, motorcycle) than flying in SE Asia -- trust me on this.
• My younger sister just puts locks on all six pairs of zips on her backpack. This only works when all compartments are secured by pairs of zips. Just remember for locks that, when outside the US, the only thing "TSA" locks are good for is providing a security hole. You can buy the TSA keys on the black market (and ebay); I reserve the use of my TSA lock only when flying internationally to/from the US.

Whatever you decide, I would highly recommend bringing along the following:

• a padlock (combination lock or otherwise) for securing lockers; we have a question somewhere on this site that has some lock recommendations
• a chain (plus lock) or integrated bike lock for securing you backpack to your bunk or other immovable furniture or the wall
• and spare luggage locks because you will lose them. I'd keep a spare TSA lock if you're based in the US for securing your luggage on your US flight.

My friend has one of these and the steel mesh is quite heavy which far outweighs any benefit you will get security-wise, who wants to drag around extra weight.

I have never used any bag locks while traveling, they are for the most part a pointless security blanket that will not stop any thief from taking your stuff. They will use a knife or just take the entire bag, not a lot you can do to stop them.

What you can do is mitigate the risk and your possible loss. Not many thieves want a pile of your smelly clothes and that is really all your main pack should contain. Any thing important, laptop, camera, phone, money, passport should live in a small day pack and never leave your person unless locked up securely at the hostel/hotel.

Also spreading your valuables is also good mitigation, keep one bank card in your main pack, one in your day pack and one in your wallet. If something goes missing you have a backup, same with cash, and passports if you're lucky enough to have more than one, split them up. I usually keep $20 or so worth of local currency in my pocket so I can buy small stuff without needing to pull my wallet out or dig through a bag.

Don't get a fancy and expensive backpack, and don't buy a net like this as it will draw a lot of attention from both normal people and thieves. Do you want your backpack to shine among all the other backpacks and luggage when you take the bus? Because a thief could just as easily take the whole thing home while you are stuck in the bus because it looked worth stealing.

Opening it up with the right tools isn't a problem so it cannot act as a good deterrent, whereas it certainly acts as a good thief honeypot.

Instead, you should spend less money on the backpack and false sense of security so that in the unlikely case it gets stolen you can buy a new one along with new clothes and etc.

This said, IMHO there are two cases that are 'dangerous'

1. while in a bus, because you cannot protect your luggage so just don't make your luggage such a yummy target!
2. while in a hostel as you cannot trust the other people (chances are that other tourists will be even more likely to steal stuff than locals): most hostels provide little closet where you can safely store your backpack, and also or alternatively, most hostels will keep your valuables in a safe if you ask for it (you could be charged too, but it may be worth it if you really want to go with your 2000 dollars macbook).

Of course, always keep your passport/papers/credit cards with you at all times. I keep them with me in the bed too, when I don't have a safe to put them in.

PS: if you are really paranoid, you could buy a little safe that you then attach in the inside of your backpack. It won't be seen so won't attract attention, but it might help in cases such as someone trying to steal from your backpack while you are sleeping next to it.