I don't necessarily agree. Building a Gnutella client is complex, but it is doable if you do it one step at a time. I started my program at the first step - I wrote a program that connected to another Gnutella server, sent "GNUTELLA CONNECT/0.4" and waited for a "GNUTELLA OK" response. With plenty of books and web pages on programming, sockets and so forth, not to mention GPL software to look at, Gnutella and otherwise, this is doable for a beginner. And I've been looking at C language for over 13 years although this is my first big C language programming project. Once I got that down, I had it send a ping after it got the OK and then had it wait to receive data (eg pongs and queries - although I also sometimes received queryhits and pushes even though I shouldn't have). So I got that down. All the data I got looked like junk so I started parsing and interpreting it into queries, pongs and so forth, the format of which I learned from the Gnutella protocol specification. After this, I gave it the ability to do a search, and then put in the functionality to interpret queryhits (which was not easy). Then I noticed some cross-compatibility problems between Windows, Solaris, BSD, Linux etc. so I started working on them. And so on and so forth, I just take it one step at a time.

As far as irresponsible developers possibly harming the network, this is true. I always try to be responsible - I have a little LAN at home and try things out there before going on the network. I also don't like overloading the pong servers like connect1.gnutellanet.com so I always use my cache before resorting to that in an effort to prevent overloading those servers.

I also don't always send queries out with a large TTL. As long as I'm testing, a few responses will usually suffice. I usually use words that give a large response rate like "live" or "love". Queries cost the network more than queryhits, as queryhits are routed while queries go everywhere.

The key thing I think is to be aware of what can harm the network. Bombarding the network with TTL=7 queries is one way. Bombarding the main pong servers is another, although gwebcache is making this less of an issue. Most of the popular well-developed clients filter out a lot of the type of the junk that can hurt the Gnutella network, making it more resilient. Usually what the developers of those big clients complain about is sending out queries/searches with a TTL of 7 too often. I usually get 10 or more responses with a search/query TTL of 4 when I search for common words like live or love, so lower your search TTL to 4 when testing and use common words...if you have a problem, increment it to 5 when you have a problem, although a TTL of 4 is fine for getting 10 or more queryhits for popular words.

As long as you're responsible like this I wouldn't worry too much about hurting the network due to being a beginner. I think the main problem is people who consciously try to hurt the network, either authors of popular Gnutella clients who have a low requery rate, or people who send bogus replies to queries with spam, and so forth. The main threat to the network as I see it is people consciously trying to hurt it, or who are at least indifferent to how much they hurt the network as long as their client gets a lot of replies, or as long as they can sell their spam, or as long as they satisfy their MPAA/RIAA paymasters. I think developers who are trying to be responsible, even if they sometimes make mistakes, almost always give more to Gnutella than they take. Hell, even the Limewire and Bearshare developers goof once in a while and harm the network in a new release until they or someone else notices the problem and they fix the bug they accidentally unleashed. But that's the exception, in my opinion Limewire and Bearshare have always done a good job, and even if you have an ax to grind with one or both of them, there are certainly less responsible clients floating around out there, which I won't name.