eileen@vax1.acs.udel.EDU (Eileen M Garland) (07/28/89)
How do I determine my own (or anyone else's) address? Is there documentation available anywhere (and if so, please explain in detail how I can get it) that gives a good introduction to News? Usenet? (Are they the same thing?) What are all these other nets I see mentioned when I read the News? Help! I'm seriously confused. How can an individual not attached to a university tap into this network? I've been fumbling my way through this News (which I love) for a couple of months now, but still have only a rudimentary idea of what I'm doing. Does everyone have this much trouble or is there something wrong with me?
mellon@zayante.pa.dec.com (Ted Lemon) (07/28/89)
Yes, everybody usually has trouble with network addresses when they start. You are on an internet site. That means that you can send mail directly to any other internet site without having to figure out how to get there. Your internet mail address is ``eileen@vax1.acs.udel.edu''. When you see other addresses in a similar form, you should be able to send mail to them. For example, my address is ``mellon@zayante.pa.dec.com''. You can send mail to me just using that address. There are two more kinds of addresses that you need to know about. One of these is somewhat insidious, so we'll examine the easy one first. The easy one is a usenet address. A usenet address consists of a series of host names, starting with one that's a direct connection from yours, and ending with the name of the person you want to get to. For example, if my machine (zayante) had a uucp connection to a machine called gondor, which had a connection to a machine called gnrrf, and I had a friend named bill who had an account on gnrrf, I could send that friend mail using the address ``gondor!gnrrf!bill''. As you can see, there are two sorts of address operators being used here - the ! (bang) and @ (at) operators. The @ operator takes precedence over the ! operator, which means that an address like ``foo!bar@baz'' tells your mailer to send the mail to the machine baz, which will send the mail to the machine foo, which will send the mail to the user bar. It happens that every machine on the internet is next-door to yours, electronically speaking. This means that if you have a friend who is on a machine that's two hops off of the internet from, say, uunet.uu.net, you can send that friend mail using the address ``machine1!machine2!friend@uunet.uu.net'', where machine1 is the machine between your friend's and uunet.uu.net, and machine2 is your friend's machine. There's another operator which acts much like an @ operator, but is used for getting around broken mailers (about which more later). This is the % operator. You can use the % operator to route mail through a known machine on the internet to an unknown machine on the internet, or on a private network. The % operator has a lower precedence than the @ operator or the ! operator (well, I'm completely not sure about the ! operator). This means that mail to foo%bar@baz will go through the machine foo on the way to bar where it will be delivered to the user baz. Now, for the insidious form of address. It's actually a nice form of address, and will make your life much easier once all of the machine on the internet and off it fix their sendmail.cf files, but for now, it does add a bit of confusion. See, at my former job, I was two hops off of the internet. You could send mail to me at ``capmkt!nli!mellon@cogsci.berkeley.edu''. This worked out pretty well, except that it was hard for new news readers to figure out how to get mail to me. Later on, we made an arrangement with uunet whereby we could register a domain address, which looks exactly like an internet address, and through some clever sleight-of-sendmail, I could receive mail from any internet host at the address ``mellon@nli.com''. When an internet mailer goes out to look for nli.com, apple.com (another internet address, run by a very competent postmaster) raises its hand and says ``I know nli.com, I'll take the mail!''. Your mailer then sends the mail to apple.com, who knows how to get mail to me. This has the tremendous advantage that you don't have to know which machines are between yours and mine. All you need is my fully-qualified domain address, and you're home free. The disadvantage comes in in that a lot of internet hosts do not yet support MX forwarding correctly (this is the magic that allows apple.com to accept mail for my old employers). So when you send mail from one of those hosts to ``mellon@nli.com'', it barfs, and you get back a bounce from an evil creature called the Mailer Daemon which says ``nli.com: host unknown''. All is not lost. If you know of an internet host that has a working mailer, you're home free. Just send the mail to mellon%nli.com@good-boy.com, where ``good-boy'' is the name of some host that has a working mailer. I won't post the name of such a host on the net, since doing so would probably result in a deluge of mail forwarded through it. If your machine doesn't have a working mailer (and I have no reason to believe that it doesn't), ask your system manager for the name of a system that does. With any luck, s/he'll be so embarassed that s/he'll actually fix the broken mailer. If not, at least you have a workaround. Good luck! _MelloN_
bill@twwells.com (T. William Wells) (07/28/89)
In article <4051@udccvax1.acs.udel.EDU> eileen@vax1.acs.udel.EDU (Eileen M Garland) writes:
: How do I determine my own (or anyone else's) address?
I'm presuming that you are asking how to do that when you have an
e-mail or news message in front of you? Well, the first thing to do is
to look at the bottom of the message for the "signature". This is a
bit of text that a user typically adds to every message; most give
some kind of e-mail address. Here, for example, is mine:
---
Bill { uunet | novavax | ankh | sunvice } !twwells!bill
bill@twwells.com
There are several pieces of information in my signature. One is
"Bill". That is just my name. Right under it is "bill@twwells.com",
that is one of my e-mail addresses. That particular e-mail address is
called a "domain address" (or one of a number of similar things). You
recognize it as such because it has a user name, followed by an `@',
and ended by a "word" with one or more `.'s in it. The "bill" part of
it is my user name; the "twwells.com" part is a "domain name" which
identifies the computer I am on.
If a signature has a domain name in it, that is the ideal name
(assuming you can make it work; not always true, sigh). But for those
souls who are unable to make use of domain names, I have also
provided a "uucp route" which they can use to send e-mail with. That
is the thing with the `!'s in it.
Unlike a domain address, a uucp route is not really an address. If
you send your e-mail to bill@twwells.com, somewhere there is a
program that figures out how to get it from you to me; but a uucp
route is just a series of instructions for how to get the mail from
one place to another. The uucp route in my signature is the text:
{ uunet | novavax | ankh | sunvice } !twwells!bill
And it tells you: figure out how to get mail to any of the systems
"uunet", "novavax", "ankh", or "sunvice"; if you can do that, put the
route from you to one of those systems together with the stuff from
the `!' on. That will be a route from you to me.
For example, if you wanted to use the uucp route information (you
shouldn't have to; your system probably deals with domain addresses
all right), here's what you might do. You'd ask someone local how to
route to one of the systems in my route; he might say: try
"udel!cbmvax!uunet" (I'm not sure that is right, though it might
work). You'd then tack that onto what follows the first `!', making it
"udel!cbmvax!uunet!twwells!bill".
There are other kinds of information in signatures, and lots of other
ways to get things from here to there, but those two cover most of
the cases.
Now, if the person did not provide a signature, you still might be
able to find an e-mail address for him. At the top of each message is
a "header" which contains a number of lines that might have an
address. Here is the header that came with your message:
Path: twwells!novavax!uflorida!gatech!udel!udccvax1!eileen
From: eileen@vax1.acs.udel.EDU (Eileen M Garland)
Newsgroups: news.newusers.questions
Subject: questions
Message-ID: <4051@udccvax1.acs.udel.EDU>
Date: 27 Jul 89 21:07:33 GMT
Distribution: usa
Organization: University of Delaware
Lines: 13
Note the second line, the "From:" line. That line has a domain
address in it: "eileen@vax1.acs.udel.EDU". If I wanted to send you
e-mail, that is where I'd send it. If the headers contained a
"Reply-To:" line, that would be the best bet, with the "From:" line
the second best.
If none of the addresses work, you could try the "Path:" line (in
messages in news anyway); it may be a uucp route that goes where you
want it. though it often goes the long way 'round. So, if I
originally sent to "eileen@vax1.acs.udel.EDU" and got a bounce
message, I might try sending to
"novavax!uflorida!gatech!udel!udccvax1!eileen". Who knows, it might
even work!
Determining your own address depends. If your site has a domain name
it is "your-name@domain-name". Other cases are more painful; ask your
system administrator.
You might want to subscribe to any of the comp.mail newsgroups:
comp.mail.elm Discussion and fixes for ELM mail system.
comp.mail.headers Gatewayed from the ARPA header-people list.
comp.mail.maps Various maps, including UUCP maps. (Moderated)
comp.mail.mh The UCI version of the Rand Message Handling system.
comp.mail.misc General discussions about computer mail.
comp.mail.multi-media Multimedia Mail.
comp.mail.mush The Mail User's Shell (MUSH).
comp.mail.sendmail Configuring and using the BSD sendmail agent.
comp.mail.uucp Mail in the uucp network environment.
: Is there documentation available anywhere (and if so, please explain
: in detail how I can get it) that gives a good introduction to News?
: Usenet?
If you haven't been given any documentation by whoever gave you an
account on the system, you should ask him for some. However, there
are also a number of documents that are posted periodically in
news.announce.newusers; you should subscribe to that newsgroup and
read those messages when they come around. Also, you should look into
getting one of the "Nutshell Handbooks". These are a series of *very*
useful books, the one I have in mind is called _Using uucp and
Usenet_. You can reach them by calling 1-800-338-NUTS or by sending
e-mail (if you can :-) to uunet!ora!nuts.
: (Are they the same thing?) What are all these other nets
: I see mentioned when I read the News? Help! I'm seriously confused.
No doubt "Usenet" has a precise definition somewhere but it tends to
get used rather vaguely to mean the collection of systems through
which the news flows. However, Usenet isn't really a network all by
itself; instead, it exists on top of other networks. In other words,
each site has some software which is able to send and receive news
and does so through whatever network facilities are available on that
system.
There are lots and lots of networks, and to make life confusing, many
systems are on more than one network. There is the uucp network, the
Internet, BITNET, etc.; some of these networks are distinguished by
the kind of protocol connecting the systems together (uucp, Internet);
others are distinguished by administrative control (though they tend
to have a common protocol as well), e.g. BITNET.
: How can an individual not attached to a university tap into this
: network?
Lots and lots of ways. You need two things: a site which is willing
to let you connect and the appropriate computer hardware and software.
Many universities are willing to let outsiders connect through their
machines; so also are many other sites. There are many ways to find
those sites, most of which amount to just asking around.
There are many sites that advertise "public access", meaning that you
can call them up to send and receive mail, and to read the news; the
problems with these are that they are often hard to get to (people
like those systems!) and you might have to pay long distance charges
as well. A list of these is posted occasionally, I think on comp.misc.
There are also many sites that you can pay for net access. Some, like
uunet, only take uucp connections; others, like Portal, will let you
do interactive access. I don't know about any of these other than
uunet, which I use.
As for the hardware, you need a computer and a modem, most any kind
will do; of course, the faster each is the happier you'll be. :-)
For software, this depends. If you want to do interactive access,
most any communications program will do; go to any computer store and
be inundated. If you want to do uucp, you need that program (which
comes with Unix), or a clone (there are a few PD clones of uucp, some
of which even run on a PC running MS-DOS and machines of similar
class).
: I've been fumbling my way through this News (which I love) for a couple of
: months now, but still have only a rudimentary idea of what I'm doing.
: Does everyone have this much trouble or is there something wrong with me?
It is not you. Or at least not wholly. It really helps to have a more
than a bit of computer background when trying to understand the net.
But even for the computer knowledgeable, the net can be difficult to
understand. The net is a *big* place. And it never stops growing and
changing.
---
Bill { uunet | novavax | ankh | sunvice } !twwells!bill
bill@twwells.combillc@mirror.UUCP (Bill Callahan) (07/28/89)
In article <4051@udccvax1.acs.udel.EDU> eileen@vax1.acs.udel.EDU (Eileen M Garland) writes:
=>How do I determine my own (or anyone else's) address?
To determine your own address, ask or send a mail message to your
systems administrator (on many systems, sending mail to "root" will
do this.) Ask for your address. In your case, your address is
eileen@vax1.acs.udel.EDU
To get other people's addresses, ask them in a conventional way, if
they know, or get them to find out the same way you did. If they
mail you a message, or if you see a posting of theirs, their address
should appear in the header, just as your does, or mine.
(I'm billc@mirror.tmc.com. Check out the header for this message.
My address should be there in the "Sender" line.)
=>
=>Is there documentation available anywhere (and if so, please explain
=>in detail how I can get it) that gives a good introduction to News?
=>Usenet? (Are they the same thing?) What are all these other nets
=>I see mentioned when I read the News? Help! I'm seriously confused.
Subscribe to the new.announce.newusers group. Also, try typing
"man rn" from your terminal to find out about your news reader.
Once you are in rn, the 'h' key will give you help.
=>
=>How can an individual not attached to a university tap into this
=>network?
This is harder. Many computer oriented businesses are on the net,
and employees have access. If that's not so for your friends,
they'll have to see about getting in touch with a service that they
can dial into from home that has net access. If your site gets
pubnet.nixpub, they have a list of such sites.
=>
=>I've been fumbling my way through this News (which I love) for a couple of
=>months now, but still have only a rudimentary idea of what I'm doing.
=>Does everyone have this much trouble or is there something wrong with me?
No, there's nothing wrong with you. It does take some getting used
to. I found that I learned a lot by reading some of the groups
under the news.* banner, like news.admin, for instance. These
groups tend to carry a lot of discussions about the net itself, and
how it all works. Another good thing is to find a real human at
your site who's really into it. You get a lot by osmosis.
Good luck!
Billchrist@forceps.Sun.COM (Robert G. Christ) (07/28/89)
In article <MELLON.89Jul27201850@zayante.pa.dec.com> mellon@zayante.pa.dec.com (Ted Lemon) writes: > > >See, at my former job, I was two hops off of the internet. You could >send mail to me at ``capmkt!nli!mellon@cogsci.berkeley.edu''. This ^ ^ Unless of course you're running the C Shell in which case you would sub \! for the ! because the ! is a special character. > _MelloN_ nice job ted. . . must be one of dem motor-sickle people!
shadow@pawl.rpi.edu (Deven T. Corzine) (07/29/89)
On 28 Jul 89 03:18:50 GMT, mellon@zayante.pa.dec.com (Ted Lemon) said: mellon> As you can see, there are two sorts of address operators being mellon> used here - the ! (bang) and @ (at) operators. The @ operator mellon> takes precedence over the ! operator, which means that an mellon> address like ``foo!bar@baz'' tells your mailer to send the mellon> mail to the machine baz, which will send the mail to the mellon> machine foo, which will send the mail to the user bar. Ugh. This is BAD advice. ! and @ were NOT intended to be used together. Up until recently, there was not even a general concensus as to which takes precedence. It has been generally agreed that @ should take precedence over !, but you can't depend on mailers to be consistent with that. Quite a number of mailers will give ! precedence and attempt to deliver mail addressed to "foo!bar@baz" to machine foo for forwarding to user bar at machine baz. Or, you may get an error because the mailer doesn't know machine foo. (but does know machine baz) Depending on consistent interpretation of an address mixing ! and @ is a poor idea at present. It is much safer to use "baz!foo!bar" instead of foo!bar@baz"; there is only a single interpretation. ! and @ together is ambiguous. As far as % handling goes, for those mailers which implement it (which are most mailers) it will do a full delivery from !'s or @ machines, and at its destination, if it contains a %, the LAST % will be changed into an @ by the mailer, and the message will reenter the mail delivery system. The upshot of which: ! and @ both have precedence over %, and "baz!foo!bar" is (usually) equivalent to "bar%foo@baz". Deven -- Deven T. Corzine Internet: deven@rpi.edu, shadow@pawl.rpi.edu Snail: 2214 12th Street, Troy, NY 12180 Phone: (518) 271-0750 Bitnet: deven@rpitsmts, userfxb6@rpitsmts UUCP: uunet!rpi!deven Simple things should be simple and complex things should be possible.
kanner@Apple.COM (Herbert Kanner) (07/29/89)
Apologies to the world if this has been posted recently:
If you are using an address of the form "aa!bb!cc" on a machine running
CShell, it is necessary to escape the "bangs," i.e., actually to write
the address as "aa\!bb\!cc".
--
Herb Kanner
Apple Computer, Inc.
{idi,nsc}!apple!kanner
kanner@apple.comjp@frog.UUCP (John Pimentel) (07/29/89)
In article <4051@udccvax1.acs.udel.EDU> eileen@vax1.acs.udel.EDU (Eileen M Garland) writes: >How do I determine my own (or anyone else's) address? > If you will note the Reply-To: if you to send me any E-mail it would be type in this manner. If I desired to send a memo to you I would direct it as follows: email eileen@vax1.acs.udel.edu. A method for anyone on the net to determine what there path is to respond to an article, note the information in the header and then abort the response. Another way is find from your system's postmaster the path. Typically, paths are: user@system.type or user@system.company or user@system.school However, some involve some relays in the path: user@system.company.relay.network The rest of the names in the path are the systems transfering information from point A to point B. =====John Pimentel=====(508)626-1000
mellon@zayante.pa.dec.com (Ted Lemon) (07/29/89)
Mr. Robert G. Christ, of Sun Microsystems, writes: >Unless of course you're running the C Shell in which case >you would sub \! for the ! because the ! is a special character. Nonsense, Mr. Christ. It should be intuitively obvious to the most casual observer that all C-shell users handle their mail from GNU Emacs, which doesn't require any silly escape characters. (': _MelloN_ :')
shadow@pawl.rpi.edu (Deven T. Corzine) (07/29/89)
On 28 Jul 89 15:37:15 GMT,
billc@mirror.UUCP (Bill Callahan) said:
billc> In article <4051@udccvax1.acs.udel.EDU>
billc> eileen@vax1.acs.udel.EDU (Eileen M Garland) writes:
eileen> How do I determine my own (or anyone else's) address?
billc> To determine your own address, ask or send a mail message to
billc> your systems administrator (on many systems, sending mail to
billc> "root" will do this.) Ask for your address.
Sending mail to "postmaster" is more general, more sensible, and more
likely to work.
Deven
--
Deven T. Corzine Internet: deven@rpi.edu, shadow@pawl.rpi.edu
Snail: 2214 12th Street, Troy, NY 12180 Phone: (518) 271-0750
Bitnet: deven@rpitsmts, userfxb6@rpitsmts UUCP: uunet!rpi!deven
Simple things should be simple and complex things should be possible.bill@twwells.com (T. William Wells) (07/30/89)
In article <MELLON.89Jul28225333@zayante.pa.dec.com> mellon@zayante.pa.dec.com (Ted Lemon) writes: : Mr. Robert G. Christ, of Sun Microsystems, writes: : >Unless of course you're running the C Shell in which case : >you would sub \! for the ! because the ! is a special character. : : Nonsense, Mr. Christ. It should be intuitively obvious to the most : casual observer that all C-shell users handle their mail from GNU : Emacs, which doesn't require any silly escape characters. : : (': _MelloN_ :') Pretty please folks, can't we stop with the esoterica, in-jokes, and other attempts at humor? The people who will most benefit from this group are likely to be *very* confused by anything that isn't directly related to the questions they ask. --- Bill { uunet | novavax | ankh | sunvice } !twwells!bill bill@twwells.com
tr@madeleine.ctt.bellcore.com (tom reingold) (08/01/89)
On the subject of "questions", mellon@zayante.pa.dec.com (Ted Lemon) writes:
$ [...]
$
$ There are two more kinds of addresses that you need to know about.
$ One of these is somewhat insidious, so we'll examine the easy one
$ first. The easy one is a usenet address. A usenet address consists
$ of a series of host names, starting with one that's a direct
$ connection from yours, and ending with the name of the person you want
$ to get to. For example, if my machine (zayante) had a uucp
$ connection to a machine called gondor, which had a connection to a
$ machine called gnrrf, and I had a friend named bill who had an account
$ on gnrrf, I could send that friend mail using the address
$ ``gondor!gnrrf!bill''.
This is not usenet, it's called uucp, which stands for "unix to unix
copy" although I think this protocol is no longer limited to
computers that run Unix. Usenet is an informal term for the set of
machines that exchange netnews. It comprises machines that are on
many different wide area networks.
$ As you can see, there are two sorts of address operators being used
$ here - the ! (bang) and @ (at) operators. The @ operator takes
$ precedence over the ! operator, which means that an address like
$ ``foo!bar@baz'' tells your mailer to send the mail to the machine baz,
$ which will send the mail to the machine foo, which will send the mail
$ to the user bar.
There is no rule that everyone agrees on that says '@' takes precedence
over '!'. Different mailers parse these differently. Many do as you
say. Others do the opposite, although thankfully few these days. But
an unfortunate many do not parse mixed addresses like this at all,
regarding them as errors.
$ [...]
Tom Reingold |INTERNET: tr@bellcore.com
Bell Communications Research |UUCP: bellcore!tr
444 Hoes La room 1H217 |PHONE: (201) 699-7058 [work],
Piscataway, NJ 08854-4182 | (201) 287-2345 [home]lum@armadillo.cis.ohio-state.edu (Lum Johnson) (08/08/89)
In article <1710@frog.UUCP> jp@frog.UUCP (John Pimentel) writes: >Typically, paths are: > user@system.type or user@system.company or user@system.school >However, some involve some relays in the path: > user@system.company.relay.network >The rest of the names in the path are the systems transfering information >from point A to point B. The address (or fully qualified domain address specification): user@system.company.relay.network is different than the path that is apparently perceived as equivalent: network!relay!company!system!user The latter actually specifies a path (thus the name) consisting of machines through which information will be transferred; the former does not specify any path at all - it serves only to _identify_ a host. A path to the host may be found, if appropriate, but usually the concept of path itself is inappropriate when speaking of Internet addresses. The point of the domain system is that `foo.bar.bletch.edu' specifies exactly one host: `foo.bar.bletch.edu', in domain `bar', a subdomain of domain `bletch', a subdomain of domain `edu'. `edu', `bletch', and `bar' are domains, and they are almost certainly not (also) hosts; there is only one `bletch' subdomain in the `edu' domain, only one `bar' subdomain in the `bletch' domain, and only one `foo' host in the `bar' subdomain. The first few examples: user@system.type or user@system.company or user@system.school are actually illegal on the Internet, unless `type' is one of the following: .COM .EDU .GOV .MIL .NET .ORG or a two-character "country code" of which there about a hundred. (These were mistakenly tacked on late in the design as a fix for the political objections of the European PTTs. A commercial organization in France and one in the US should not be in separate domains; they should both be in the .COM domain. But that's another rant.) Some pseudo-domains (eg, .BITNET and .UUCP) are tolerated, since otherwise it would be still more difficult to move mail between the Internet and other networks. No RFC requires anyone to recognize such pseudo-domains or do anything useful with them, however; it merely works better if the rules are not enforced too strictly all the time. The reasons that .BITNET and .UUCP are pseudo-domains rather than authentic domains are: these "domains" have no domain structure (ie, it is always `foo.bitnet', never `foo.bar.bitnet', because the `bitnet' pseudo-domain does not (and can not) contain any subdomains - to oversimply, the name space is "flat" rather than "hierarchical"); and these "domains" are not registered as such with NIC.DDN.MIL (nee SRI-NIC.ARPA), with whom all legal domains are registered. This is not really the newsgroup for discussing questions as difficult as this anyhow; I'm redirecting this to `comp.mail.headers', which seems to be where such things are discussed. Or you may send mail to `postmaster@osu-20.ircc.ohio-state.edu'. Lum -=- -- Lum Johnson lum@cis.ohio-state.edu lum@osu-20.ircc.ohio-state.edu "You got it kid -- the large print giveth and the small print taketh away." -------
eugene@eos.UUCP (Eugene Miya) (08/08/89)
I think there are several problems here.
1) there is a problem of educating new users. There must be two basic ways
people are getting into news: a) start a news program and unsubscribe
(this takes lots of time, I'm just now rebuilding a newsrc from a crash).
b) start reading a few groups, adding as time goes one. This latter is
hap-hazard. Particularly dangerous because it creates semi-informed
users (worse than uninformed).
2) there is a problem of redundancy. Witness we have two newusers
subgroups. Questions in one are identical to Q/Answers in the other.
Some people aren't reading that group. And I don't think they are all 1b).
The ultimate technical problem is the news interface. Recently I've
had a chance to visit several sites (non-Unix: VM, VMS, etc.) running
all kinds of different software: just mail, Notesfiles, you name it,
some one has it reading news. Until these interfaces are a bit more
consistent (many different capabilities), I don't see any hope of
improving the redundancy thru education. You have some neat stuff here,
you just have to educate your people better, and you need better tools
to do that as well.
Another gross generalization from
--eugene miya, NASA Ames Research Center, eugene@aurora.arc.nasa.gov
resident cynic at the Rock of Ages Home for Retired Hackers:
"You trust the `reply' command with all those different mailers out there?"
"If my mail does not reach you, please accept my apology."
{ncar,decwrl,hplabs,uunet}!ames!eugene
Live free or die.jeffb@Apple.COM (Jeff Baker) (08/09/89)
Just a simple specific question regarding USENET policy towards the advertise
ments of firearms over the net (i.e. rec.guns). Is it ok to post ads of this
nature? In parousing that particular bulletin board, I've seen nothing actual-
ly being advertized for sale. Just want to make sure that I'm doing things
right before I post anything that may cause problems later on.
Jeff