AFAIK, you can't block just the upload... If you want to leech, a firewall won't help. You can reduce the upload speed at best... (but that will impact your download speed too).
I want to get the up/down ratio to as small as possible, I'm getting up/down rations of like 1.5-2. I want the up be always smaller than the down.
You would need a packet filter such as L'n'S and make a raw rule to intercept the packet type, however, eMule 0.47c had an additional feature that can enable protocol obfuscation (to bypass ISP throttling) and have not looked at that. - Stem
So you want to have up-down ratios close to 1 or worse? That's all? Well, that's easy then! Go to preferences and limit the download speed to whatever you like! It's in options---> connections window.
Well, you said "up-down" ratio 1.5 to 2. Not down-up. Things in emule are simple... Beyond 10 kb/s of upload, you have no download limit. So if you give at LEAST 10 kb/s of upload, you should be able to download to full potential. BUT, in practice, the more upload you give, the more download you get, because you create more credits to other clients. 1.5-2 is a good ratio for emule. If you want higher ratio, i suggest you increase the files you have on download, and raise your upload to about 80% of your line's capacity. In the connections window you can limit at your pleasure the download and the upload separately. Remember. Emule is not for speed (that's what torrents are for). It's for getting heavy files and old-rare files with patience.
Well, i tried to explain, but you confuse me... Usually people want to download faster, but i think you want the opposite...Anyway... YES, go to the connections window and limit the upload to whatever you want. Just TICK the box and slide the cursor to the value you prefer (i don't know what's your internet connection!). For example, you go there, limit your download to 20 and your upload to 20 and what do you get? a ratio of 1, IF you manage to download always at 20. A bit less otherwise.
Here here: Slide the cursor. Here as an example i have moved it to 45. You can move it as low as 1. http://img11.imageshack.us/img11/5906/17622193.png
In other words you want to leech. P2P is based on sharing, people thinking your way is not the right way to go. Would you be able to download what you now download if others (those sharing) would behave in similar manner?
Why are you using emule still? There are other programs that control upload speed with just a mouse over. But you need to keep the ratio balance otherwise it would effect the downloading speed. Emule and Limewire are not what I call real P2P programs. RC4 encryption works very good for ISP throttling down and then you need PG2 to mask your IP, plus block rouge/bad IPs. It's a game of chess move one way fast speeds, then move another way slow speeds.
Actually, they are And nowadays eMule seems to be making transition to Kademlia as servers either fall off or are bogus. More modern apps like BitTorrent and its variants though may not count as 'true' p2p application, as they rely mostly on central tracker .