Pi in the Sky

Understanding eMule (and part 3)

Posted on June 30th, 2007 at 8:14am by Pi.
Categories: Internet.

Before reading this long gabble, I recommend reading the two previous gabbles. In this one, I give some advices to use eMule or some other eMule based client, such as eMule ZZUL, and as dessert, some lil tricks to take the max out of it.

You’re reading the third and last part of the series Understanding eMule. You can also read the first part, which deals about how eMule and the eDonkey network work, and the second part, which talks about how to choose the right eMule version, and how to configure it.

Searches

Apparently I’m popular between the people who knows me for finding difficult stuff. What is very curious to me, since the majority of times I’m able to find them at first or second try, while the rest of people say “it’s not in eMule”.

Sometimes it could be a little mistake writing: if one searches for the free distribution movie Star Wreck (The Pirkinning), it’s different to search for “star wreck” than for “starwreck” or “starwrek” or other variants. That’s why one has to be sure of the correct name of what it’s being searched.

eMule has some searching methods. In the search section in eMule, in the top left corner, just below where we enter the search, there’s a combo box to select the method. There are four, although generally we should use the one called “Global (Servers)”. With this method, the search is made in the server we’re connected with in that moment. If the server returns a good amount of results, then it stops there. But if it returns few or no results, then the search is propagated to all the servers you have in the list. That’s why it’s important to have good servers that don’t return fake results.

When the search is propagated to other servers, it’s done sequentially, and there’s a progress bar in the lower part of the eMule window. This search could take a bit more.

Besides that, the servers have a limit for results. Usually they only return a maximum of 300 results at a time, but if you need more results, you have the “More” button to obtain the next 300, until all the results are found, or the top limit is reached (about 1,800 results). If the “More” button is enabled, it means you can obtain even more results, but if it’s disabled, it means that you’ve already got all the possible results.

Another search method worth mentioning is the search in “Kad Network”. It’s just below the global search. Although the majority of the clients who are in Kad are usually also connected to the eDonkey network, there are times that it’s advisable to search in the Kad network. You can find things that aren’t indexed in the eDonkey servers. There are some technical reasons for this to happen, i.e. the servers only index a limited number of files per client. I don’t know what the limit is, but let’s say it’s one thousand. If you share two thousand files, the first thousand are indexed and available in the servers, but the other thousand are not.

But in Kad, which doesn’t use servers for indexing, you can search for and find that remaining thousand. It’s useful to find things that are many small files; for example, all the creations of Gil Elvgren (genious pin-up artist). But remember to return to the global search method when you’re finished, because in Kad the search has a reach limited by the distance of the noded (tech gabble, but trust in me) and if you don’t notice to make searches with “Global (Servers)” method again, maybe you’ll not find what you search for. Oh, and searches in Kad usually take long.

Once we’ve got a lot of search results, sometimes it’s needed to search in those results. I.e., we search for “star wreck”, and we get about 50 search results. Which one is the file we’re searching for? The first thing we should watch for is the type and size of the files: if it’s a movie as Star Wreck, most probable it’ll be around 700mb. We can sort the results clicking on the column header, in this case the column “Size”. It’s also useful to sort by “Availability (Sources)”, to see which are the most popular files (shared by the larger amount of sources).

You should watch out this column. If a file is only shared by a couple of cources, you’ll need a lot of time to download it. If it’s shared by a couple of hundreds, it’ll be dead easy. The files with a lot of sources are marked in blue, to identify them quickly. Another important column is “Complete Sources”, which says which percentage and amount of sources have the complete file. If all the file is marked in red, and in this column you see 0%, this means that no client has been detected with all the complete file, what usually means that you’ll never be able to finish downloading the file.

But sometimes it’s good to try it anyway: in very rare files, maybe you’ll find one with 0% complete sources because in that very moment, the only client having it isn’t connected (or you don’t find it for any other reason). If you try to download the file, and you see that in a couple of days your eMule hasn’t seen it complete ever (in the transfers side, it’s the column “Seen complete”) then forget about the file, or in other words, right-click over it and “Cancel”. But maybe you are lucky and you’ve seen it, and even downloaded it, when apparently the file looked impossible to download.

Fake files

One of the big problems in eMule are the fake files. In the eDonkey network, even when the files are searched by the name or part of it, the files themselves are identified by the contents. To each file of different size and contents, it’s assigned an almost-unique identifier, based in a file hash, analyzing the content with a hash algorithm. In the eDonkey network it’s used MD4 (Message Digest Version Four). Thus, a file could have any name; but when it’s indexed and searched for, you can find and download a specific file. Independently of the name.

This also means that any scumbag could rename Star Wreck as “Pirates of the Caribbean: the Return of the Skeleton Monkey”. That way, unaware and pirateful people who is searching for “pirates caribbean”, sees that file, and thinks: “shoot, there’s a fourth part! Whatcoulditbeabout?”

However, after downloading it, he’ll get a nasty surprise, because instead of the fourth and unexistant part of Pirates of the Caribbean, he finds a movie in finnish. Although usually what one finds isn’t a movie in a strange language, but a porn movie.

To detect fakes, the first step is that they should be believable. One has to be a little common sense and not download the fourth part of Pirates of the Caribbean when the third hasn’t been premiered yet.

The second step is to see if the server returns alternate names for the file. If this happens, in the search result list, next to the little file icon a plus + sign will appear. When clicking on it, a list of alternate names will appear below the file name. If e.g. one of the alternate names are “Asses of the Caribbean volume 6″, then it’s probable that the file is a fake.

If everything looks normal, there’s a third step which is advisable to follow to be sure. Once we’re downloading the file, we allow a few minutes to pass so eMule makes the petition to all the sources. eMule asks for the file to another client according to its MD4 hash, but the source also returns, as additional information, the name it is using to share the file. So let’s imagine we’re downloading a file named “star_wreck_in_the_pirkinning_subtitles_english.avi”. If we right click over it, a new window is opened with all its information. In one of the tabs, “Name”, they appear all the alternative names this file is being shared with (according to the sources), and the number of sources for each alternate name. It’s common that there are small variations in the file name. Maybe a source has the same name as you do, but maybe another has “Star Wreck (In The Pirkinning) with english subtitles.avi”.

The bad thing is when a source has the name “Asses.of.the.Caribbean.vol.6.with.Tonni.Buttxon.by.YourHornyNeighbour.avi”. If there are many sources with a radically different and suspicious name, then don’t trust it. If the majority has a different name, then some joker is trying to laugh at us.

Another way of detecting faskes is looking at the file comments, which are accessed in the same way as the alternative names. In a comment, people usually rates the movie, or the audio and video quality, or if it’s a fake. Pay attention to the fact that in the comments, the shared file name of the source which set the comment is also shown. I say that because “it’s a fake” is a misleading comment. Sometimes I’ve downloaded stuff which was what I wanted, but someone else downloaded it with another name and instead of saying “it’s a porn movie” or something similar, they say “it’s a fake”, and don’t say clearly fake of what. Maybe they wanted to download porn but found themselves with a movie in finnish ^_^

It’s also possible that what we’re downloading is what we searched for, but that it has an awful quality. That’s why it’s good to pay attention to the names and sizes of files, and to comments to see what people say.

Incomplete files

In eMule traffic, in the list of files you’re downloading, there’s a progress bar with some colours. Each vertical piece corresponds to a part of the file (9.28mb). The bigger the file, the more parts it’ll have, and the more colourful pieces you’ll have in the progress bar. The black pieces are parts you’ve already downloaded; the blue pieces, the parts that you’ve not downloaded yet, but are available (the more darker, the more sources are for that part); and the red pieces are the parts that aren’t available in that moment.

If you’re using the ZZUL mod (which I talk about in the previous article), then the parts you have complete are marked with a dark grey. It’s possible to have a part incompletely, i.e. the first seven megs. Until a part is complete, it’s not shared.

The problem comes when the parts that we’re missing are always in red. You should watch out the “Seen complete” column, to see when the file was seen complete for the last time. If it says “Never”, or a date of long ago, it’s better to quit. Having incomplete files shared is counterproductive for the network, for people and for you. It’s better to search for another alternative file.

Sometimes, a file is complete when we start downloading it; but due to gremlins, or to incompatible protocols or eMule mods not following the good manner guidelines (that’s why I don’t recommend many mods!) maybe only certain parts got distributed, while others remain without having been shared in only one client. Maybe that client thought that he has shared the file long enough; or maybe he went on vacation; or maybe he got internet down due to not paying, whoknowswhat. If we see that a file has been seen complete last time a month or two ago, then goodbye.

It’s also possible that due to a mysticalinconceivable reason there was some corruption in your hard disk or in the transfer, and you got a bad part (or the .met file corrupted). Then, no matter how many sources there are, no one will be able to help you. Maybe a day you see a file with many sources and happily downloading, and a week after you see that what you’re missing is always in red. Then the best idea would be to cancel that file and start again. This is very rare, but I’ve had it happened to me at least once, and maybe twice (damn alzheimer).

Finally, there are times when the only sources that have a complete file are also collapsed. Their waiting queues are full (because there’s a limit of how many people a client has in its queue). Or it’s very long and advances slowly. Advancing in some of these queues can take hours, even a full day. The only solution is patience, a lot of patience. Generally, sending messages to these sources telling them to raise the priority of that file isn’t successful most of the times, although I try it many times.

To share or not to share

In the previous two parts of this series of articles about eMule, I’ve insisted on the importance of sharing, and in the benefits it brings. Even if you’re not a generous person, you should know that sharing in the eMule network benefits you. Sharing helps that the parts you don’t have arrive at you more quickly.

Let’s imagine that you’re downloading a 27 megs file, that has three parts: 1, 2 and 3. There aren’t many complete sources, let’s say five. There are other three clients trying to download that same file. And you already have part 2. If you share a lot and well, it’s possible that the other three clients get that part 2 from you. If they already have that part, like you, when they ask for parts to the other sources, they’ll ask for parts 1 and 3, what will make that the parts you don’t have are distributed faster. And where first you had five sources for parts 1 and 3, now maybe you had six or seven for each one.

You could think “well, part 2 will be eventually sent by one of the other sources which are complete”. Parts are distributed in a random way. If a client which has nothing, asks for a part of the file, it has the same possibilites to obtain part 1 than part 2. If it obtains part 1, that’s another source for you, but if it obtains part 2, it doesn’t benefit you at all, since you already have it. Being sure that the other clients ask for parts that you don’t have is beneficial for you, and that’s made by sharing the parts you already have.

Besides, uploading what you already have to those clients which are already downloading the file, makes that you have credit with them. Thus, when you get to ask to them for a part of the file, you advance in their queue faster, for having uploaded something to them. Everything is positive!

So sharing is not only a way of being generous and altruist, and help to maintain the eDonkey Network in good shape; it’s also practical and beneficial for oneself.

That’s why it’s also good to have the rarest files in higher priorities. Sooner or later, more probably sooner, you’ll download that file with 200 sources, but the one which only has six sources need special caring. And to be really generous, once you’ve downloaded it, be sure to share it for a long time.

On the other hand, the files which have a lot of sources, and which probably take up the most of your queue, it’s better to move them once they’re finished, that way we’re sure that our bandwidth is used for more rare files. If a file had 150-200 sources while you were downloading it, it’s survival and distribution in the network are assured; while it’s advisable to have a couple of weeks or months other files that you saw they took a long time to download.

Friends and other myths

Next to “sharing is bad”, the other big myth in eMule is the one about friends. You can add friends to your list (they appear in the “Messages” section of the main window), what is useful for certain things. I.e. to maintain contact with someone who has files you’re interested in, or with someone who is helping you to distribute something.

But what people believes is that just by adding people to the friend list, they’re assigned a special priority so they’re waiting in queue less time. There are a lot of people who, actually some time ago, used to put in the comment of a file “exchange of friends”.

The reality is that eMule, the official eMule, doesn’t assign any special priority to the clients which are in the friends list. It can do it, but it must be done manually. For that, a friend slot must be reserved, it’s done right-clicking over the friend, and selecting “Establish friend slot”. This reserved slot, the friend slot, is, in the official eMule, unique. There’s only one. If you assign to other friend this slot, then you’re removing it from the first friend. This friend slot assigns a very high priority to the affected friend, so he waits less time in the queue.

The eMule ZZUL mod is a bit different. It has a feature called ZZ FriendSlots. It means two things: you can assign more than one friend slot, and instead of just a higher priority, what happens is that they get assigned all the upload bandwidth. In this case, you must be careful of not having too many friends, because they can assault and collapse your bandwidth. In ZZUL, friends are used to distribute new files to people interested in redistributing and sharing them, and for that the faster, the better. eMule has never been meant to be good to share files between to specific persons, so sometimes it was needed to exchange the file first by other methods.

To avoid that people makes little groups of friends who only share between them with ZZUL, FriendSlots has a particularity: what you upload to friends, isn’t counted in the upload/download ratio. This means that if you only upload to friends, you’ll end downloading little to nothing. ZZUL will think that you’ve not uploaded anything, and it will not allow you to download from other sources until you share something with someone who doesn’t have a reserved friend slot. That’s why the friends thingy must be used carefully and moderately, and only when it’s needed.

Besides, ZZUL remembers to which friends you’ve given reserved friend slots between two ZZUL sessions. The official eMule doesn’t do it, thus each time we re-run it, we need to reassing the only friend slot we have, if we want.

So the friend subject is not as people use to think; and in any case, it must be used carefully, the same as other eMule features which can be used for abusing.

Comments and correct names

To finish all this tedious stuff, I recommend that people stops being lazy and start putting comments to the files they share. It’s specially important and useful for fakes, rare files, or things oneself has created and put to distribution in the eDonkey network.

To put a comment to a file, you must share at least one complete part. Go to the “Shared Files” section, right-click over the file you want, and select “Comments…”. In the window which is opened, you can put a comment, sadly very short. Sometimes you must do strange things to put something so it fits.

You can also rate the file, from “Invalid/corrupt” to “Excellent”. There’s no consensus about how to rate things; there are people who rates movies according to the movie itself, if it’s good or bad, while other people rates it according to the quality of image and sound, even if the movie is crap.

That way we can warn other users about the quality or content of a specific file; if the file doesn’t serve for a particular purpose; if the file has been months without being complete; or to publitize something we’re sharing because we want. If people used more often the comment feature, people would get less problems, and the good files would be shared often and better, and they would be easier to find.

One alternative to the comment length limitation is to be sure that the filename is correct. We can change it safely, knowing that as long as we don’t change the contents, it will keep being shared correctly. We can add some other data to the file name, with the added bonus that it will appear in searches (comments aren’t used in searches). For example, we downloaded the file “starwreck.avi”, but we rename it as “Star Wreck (In The Pirkinning) english subtitles [amateur finnish movie, good quality].avi”

Conclusion

Probably many of the things I’ve mentioned are known to users with some experience in eMule; but it’s never a waste to revise what one thinks one knows, nor learning some new little trick that for some esotheric reasons one didn’t know. I’ve tried to describe the most practical tricks and knowledge to take the most out of eMule.

This has been the last part of the series Understanding eMule. I hope it has been of help, even if it was just a little to one person. Have a happy eMuleing!

I’ve been waiting to put in written form a kind of tutorial and trick repository about eMule for a long time; but I did now to help a friend. This article series is dedicated to her.

3 comments.

Two evil devil servers »« Understanding eMule (part 2)

Two evil devil servers »« Understanding eMule (part 2)

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