AOL Now Publishing SPF Records

SPF Fan writes "It looks like SPF is starting to catch on with the bigger ISPs. AOL is now publishing SPF records which you can verify with 'dig aol.com txt'. Will Hotmail and Yahoo be far behind? Who else is publishing SPF records for their domains? Slashdot has covered SPF in the past a couple times."

Comments

Suggestion for submitter

[ObviousGuy]

Don't assume we all know what "SPF" is. Unless you mean "Sun Protection Factor", you are leaving the /. readers to wonder.

Please, if discussing a topic that is not widely known, put a short description or definition in the article writeup.

Thanks.

Re:Suggestion for submitter

[use_compress]

you are leaving the /. readers to wonder.

He did provide a highly visbile link to the definition of SPF. That page gave a very good overview of the topic. Why cater to (define NOT_FLAMEBATE)lazy people who don't read the articles?

Re:Suggestion for submitter

[Malc]

You're new here, aren't you? You must have hijacked that 206K account. /. lesson #1: don't read the story /. lesson #2: be paranoid about links... they might go to goatse.cx. It doesn't happen very often anymore, but be paranoid anyway /. lesson #3: post comments that make it blatant you didn't read the story

Thank you.

Re:Suggestion for submitter

[drooling-dog]

Why cater to (define NOT_FLAMEBATE)lazy people who don't read the articles?

Well, one reason would be that linked articles often get slashdotted before most people get to them. Another is that some would like a brief heads-up without having to read an entire treatise on the subject. But then, real geeks know that keeping outsiders in the dark is the key to their mystique...

AOL

[joostje]

Who else is publishing SPF records for their domains?

[AOL]
Me Too!
[/AOL]

Re:boo

[Anonymous Coward]

In case any windows user is interested, but cant use dig:

$ dig aol.com txt

; <<>> DiG 9.2.2 <<>> aol.com txt
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 49576
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 4, ADDITIONAL: 4

;; QUESTION SECTION:
;aol.com. IN TXT

;; ANSWER SECTION:
aol.com. 300 IN TXT "v=spf1 ip4:152.163.225.0/24 ip4:205.188.139.0/24 ip4:205.188.144.0/24 ip4:205.188.156.0/24 ip4:205.188.157.0/24 ip4:205.188.159.0/24 ip4:64.12.136.0/24 ip4:64.12.137.0/24 ip4:64.12.138.0/24 ptr:mx.aol.com -all"

;; AUTHORITY SECTION:
aol.com. 3071 IN NS dns-02.ns.aol.com.
aol.com. 3071 IN NS dns-06.ns.aol.com.
aol.com. 3071 IN NS dns-07.ns.aol.com.
aol.com. 3071 IN NS dns-01.ns.aol.com.

;; ADDITIONAL SECTION:
dns-02.ns.aol.com. 3273 IN A 205.188.157.232
dns-06.ns.aol.com. 1887 IN A 149.174.211.8
dns-07.ns.aol.com. 431 IN A 64.12.51.132
dns-01.ns.aol.com. 192 IN A 152.163.159.232

;; Query time: 110 msec
;; WHEN: Fri Jan 9 09:06:32 2004
;; MSG SIZE rcvd: 405

Don't be silly

[KalvinB]

Nerds don't go out into the sun.

Ben

Re:Some of us have reasons for spoofing our addres

[pe1chl]

I would advise you to read before you write.
SPF was invented especially to cater for your situation. The quick way out would have been to use MX records as the only validation, but this was not done.

Re:How does this reduce spam in any shape or form?

[JanneM]

Spammers can just use their own domain

Yes, they can. And all I need to do is to let the domain be one feature to do adaptive filtering on. Two mails on penile enlargement, and no non-spam email from one domain, and that domain will be a pretty clear signal to throw stuff away. Time for the spammer to get a new domain.

Many will not implement this!

Well, whether everybody implements it or not, it does give me another factor to filter on. If the mail comes from a domain that does not implement it, that's grounds enough for a big, fat -5 spamassassin rule right there.

Oh, and as more and more people implement this, those who do not can be more and more severely punished by spam filters (as the exceptions for any one person becomes few enough to whitelist and so on).

But if you blacklist any domain without it, some people won't be able to send stuff to you anymore!

Cry me a river.

Re:How does this reduce spam in any shape or form?

[skaag]

My own experience:

I happen to be hosting a few domain names that attract a lot of joe jobs, if this method helps me reduce the amount of joe jobs by 5%, it was worth it. The amount is simply HUGE.

The Deterring factor:

If the Spammers are smart enough to check my domain for SPF records before doing a joe job on it, they might not select it for their joe job, simply because they will know their campaign might not be as effective as it would be if they used another domain that does not publish SPF records. So the deterring factor is important here!

Conclusion:

Every effort counts. And let's not forget that sometimes, all it takes for an idea to catch on is some large corporation using the technology or technique, and it will catch like wildfire. I'm also publishing SPF records for my own domains, and checking for them as well (with the help of qpsmtpd which has a nice SPF plugin).

Re:boo

[Saven Marek]

> 2) Spammers tend to use made up domains anyways.

This is true, but combined with domain checking AND SPF I can see it being more powerful than both.

for ex.
spammer makes up umergeh.drewhs.com
email gets canned because the domain is fake. lose for spammers

spammer sends faked address from aol.com
SPF shows its a fake sender (rteal IP not match aol.com spf list). lose for spammers

spammer at aol sends real spam from aol.com
aol come down and bite spammers head off, spammer goes to jail. lose for spammers!

SPF is only one tool, and there are many combine them together and you have strength

mac desktops, dare to be nude

How about dynamic IPs?

[ivern76]

This just screws the people on dynamic IPs even more than we were before. I guess I'll have to keep paying a monthly fee just so I can have a smarthost to tunnel my mail through, since even more mail servers are going to think I'm a spammer now.

Why this is a big deal

[mattbee]

It means that any system administrator can configure their mail transfer agent to bin any spam pretending to come from aol.com with a 100% success rate. And this goes for anyone else publishing an SPF record for your domain.

SPF is a proposed standard for a domain owner to tell mailers where mail From: that domain may originate. The domain owner publishes a DNS TXT record for their domain with (at the simplest) list of IP addresses. Participating mail transfer agents can then look this record up and make a policy decision on whether the mail is likely to be legitimate. The presence of an SPF record on a domain at present means that while you still can't be sure when you're handling spam, you can be sure when you have a piece of non-spam because the SPF record tells you so.

SPF is not a wholly original idea (e.g. up "designated mailer protocol"), and certainly not the simplest implementation but the important factor is that its proponent, Meng Wong, is an excellent lobbyer and spokesperson, as well as someone who as the nous to put forward a useful protocol (he founded pobox.com). It's currently at the point where lots of implementation are being written, with the canonical version being Meng's Perl modules. Currently I'm helping to finish the C implementation which will shortly be integrated into qmail and exim.

The tipping point (I hope) will be when a domain not publishing an SPF record or publishing a globaly permissive one will be considered "obviously" untrustworthy. Combining SPF authorisation with a more traditional "From: domain blacklist" will give spammers a very very hard time indeed forging mail. But AOL publishing a record (we hope) shows the way the wind is blowing: the rest of the world does seem to have to change their mail server configuration to keep mail flowing to AOL.

So go on, it's dead easy, publish a record for your domain now. Tell people where your mail comes from. Look, there's even a wizard to help you.

Re:Why this is a big deal

[jeroenvw]

The presence of an SPF record on a domain at present means that while you still can't be sure when you're handling spam, you can be sure when you have a piece of non-spam because the SPF record tells you so.

So, as a spammer, you only have to publish an SPF for your own domain, and your mail is garanteed to be nonspam?

No, you have it wrong: Mail coming from hosts not allowed by the SPF, is guaranteed to violate the policy of the sender domain. SPF is basically saying: ``Hey, to whom is interested, mail coming from one of oud adresses, will always be send by these mailservers. So if you receive them from other means... We didn't do it!''

But indeed, if the domain and its users are trustworthy, you may decide that spam isn't likely to come from them. While ISP's might be trustworthy themselves, their users as a whole are not.

the rest of the world does seem to have to change their mail server configuration to keep mail flowing to AOL.

Wrong again, it's about mail flowing FROM @aol.com adresses. Mail going TOWARDS aol has nothing to do with it. Even if AOL will be implementing SPL while recieving mail themselves, if you don't use SPL, you're not blocked, and also, you need to change your DNS, not your mail server, if you want to implement SPL for outgoing mail of your domain.

Re:Why this is a big deal

[Malc]

Check the FAQ. The topic heading is "But that breaks forwarding!"

anti-spoofing

[colinleroy]

As I don't think this will stop spam (at least not before massive adoption, as others said), I think it can protect us from having a spammer using our email address as From:.
I publish SPF records for my small domain now, and next time some dumb ISP complains getting spam "from me", I'll be able to tell them to go and check my SPF records, and to match these with "my" spam's headers.

Of course, this is for my little domain with few users, all well-educated enough to use authenticated SMTPS to my server.

Some of the benefits.

[mcroot]

Some people seem to be missing the point of spf. SPF is a mechanism that allows people to publish their own records to defend themselves against joe-jobbing. Anyone who has been joe-jobbed will be all over something like this. The fact that publishing these records benefits you directly, will help something like this spread in a timely manner.

It's also beneficial in the regard that when rolled out to where it becomes standard, mail will be far more accountable, and as spammers start joe-jobbing those people who have not yet published these records, it will only help motivate those hold-outs to get on the bandwagon and defend themselves.

This does reduce spam

[dybdahl]

It reduces spam because spamfilters like spamassassin etc. can add extra points to those e-mails that did not verify against SPF records.

If Red Hat adds SPF verification to their default spamassassin configuration files, a lot of companies will start to add SPF records to their DNS.

If I send an e-mail to a RoadRunner mailbox, it is rejected. Why? Because my mailserver is a Linux box on my ADSL internet connection, and RoadRunner blocks all e-mails from residential IP ranges. With SPF, such filtering can be made much more careful, making it possible for me to send e-mails to RoadRunner customers again.

Re:How does this reduce spam in any shape or form?

[krymsin01]

You are doing a reall good job at copy and pasting past comments for karma whoring.

I bet your parents are proud!

Tag it

[Epeeist]

How about using the proper tag,

<acronym title="Sender Permitted From">SPF</acronym>

Or if you want to include it in a link

<a title="Sender Permitted From" href="link">SPF</a>

Re:Would someone explain this to a simpleton?

[Motherfucking Shit]

I read the page but it's too early in the morning for me. Would someone please explain the idea behind SPF _understandably_?

Suppose you own a domain, let's call it sharpfang.com. You have a cable modem and your IP address is always 24.95.x.x. If you're sending out email from sharpfang.com, you always do it from your cable modem.

One day, you start getting a lot of bounced spam. Some spammer, for some reason, has decided that he would forge his latest batch of spam from @sharpfang.com email addresses. What a dick!

So, you set up SPF records for your domain. The SPF records are basically a way of telling other mail servers, "I only send mail from my cable modem connection, which will always have an IP of 24.95.x.x. If you get mail claiming to be from sharpfang.com, but it didn't come from an IP address inside 24.95.0.0/24, it's bogus!"

Now, enlightened mail server admins can reject any email with an @sharpfang.com return address but an origin IP of somewhere outside of 24.95.0.0/24. Of course, if your IP address or range changes (e.g. you're traveling, you switch ISPs) you simply update your SPF records in DNS.

SPF has dual benefits: it can reduce the load you get from joe-jobs (assuming some of the recipients' mail servers honor SPF), and it helps everyone else identify spam.

Other problems with SPF

[0x0d0a]

...SPF technically wise sucks

Agreed. I'm going to cut-and-paste the set of flaws I was talking about *last* time SPF came up on Slashdot:
First, this is nothing more than an authentication system. It's designed to allow a server to authenticate itself as a trusted source for a domain's email. However, the designers chose to use DNS as a transport mechanism. Not a good idea. DNS is designed to be lightweight and low latency, not to be secure. It's pretty easy to spoof DNS responses. Plus, DNS data tends to get cached. All you need to do is spoof a response, the nameserver's cache is poisoned with false data, and the next N emails (until the cached data expires) are accepted as valid.

Second, this system relies on having everyone implement such functionality. Spammers don't give a damn about return addresses, so they can send email with a from address at any domain. The annoying and ineffective attempts at stopping all open mail relays on the Internet illustrate the failure of this model. A security system that relies on correct implementation over the full Internet to function properly will not work in real life.

Third, this fails to deal with throwaway domains. The authors waffle a bit about them, and finally come out and admit that more mechanisms are required. Dammit, if we had a good PKI trust-ranking system (which is the sort of thing that they are requiring to fix their failings) we wouldn't need this system at *all*, since we could simply sign email and have trust rankings for users.

Enough about the bad design: other reasons I don't like it include:

* The authors have made a decision to make it really annoying to send email from a machine, and have to work with your ISP just to have a mail server. There are plenty of more solid antispam proposed mechanisms that do not place restrictions on who runs what servers (pay-per-email or pay-per-initial-email, PKI systems). This is much more in line with the way the Internet works for most services.

* There is a supposedly trusted authentication system being spread across the entire Internet over an insecure transport protocol.

* DNS caching can make moving an SMTP server or setting up a new one take a significant amount of time.

* IP-based auth isn't a great idea anyway, for a number of reasons. The authors claim that it isn't a huge issue, because IP spoofing is harder (I disagree -- things like Mobile IP have made it harder to *block* IP spoofing).

* Users have no control over what gets blocked. If I *want* to receive email of a particular type, I can't. Two ISPs (sending and receiving) are the ones that determine what mail I can receive). This is perhaps acceptable within a company, but annoying and goes against traditional Internet structure.

* It does nothing to avoid compromised end user machines.

* It does nothing to deal with throwaway accounts.

* It does nothing to deal with misconfigured servers.

I see a problem here....

[matth]

Question on this whole SPF thing.
I'm interested in it but have a slight issue with it at the moment that
I'd like to get resolved.

My domain is: mydomain.com
Customer A is traveling and is using his e-mail of joe@mydomain.com
However, I do IP filtering on my mail server (not SASL AUTH), for my
dial-up pools.
When Customer A is at hotel he must use their mail server to send mail
out, so his mail will be rejected because the hotel mail server isn't
listed in mydomain.com's SPF txt list.

You suggest running SASL AUTH as a work around for this, however in my
experience this creates MORE of a spam problem then not using SPF..
here's why:

On a mail server with over 40,000 users it's relitively easy for someone
with a password cracker to hammer away at common names like 'joe'
'jeffp', etc and try to get some passwords. Once they have a
username/password combo they can happily send e-mail out as that user
through MY mail server, and I can't do anything about them. Doing IP
filtering requires that they are on MY network to send mail through MY
server, thus allowing me to terminate/prosecute/etc the person.

AOL will likely remove these SPF records today

[wayne]

According to a message from Meng Weng Wong (the author of SPF), AOL will likely remove these SPF records today (Friday). There are still kinks that need to be worked out, and AOL doesn't like to make big changes like this to be permanent and/or last over the weekends until more testing has been done.

See: this message on the SPF mailing list

SPF is NOT a problem for you,

[autopr0n]

For instance, the box on which I get all my mail, to which all my mailing list subscriptions go, and which is associated with my online identity everywhere I have one...is located halfway across the continent from me

Two solutions.

1) The "hard" but proper way, setup SPF records from all the machines you will be sending mail from or

2) Simply send all your mail out through the box you get it in from. What's so hard about that?

Anyway, I'll be happy to let anon mail through just for your convenience, so you don't have to setup SPF once every 6 months, or wait for your email to get forwarded through your own mail server, if you'd be willing to go through and delete the hundred or so SPAMs I get each day. Sound like a fair deal?