AOL Now Publishing SPF Records 340
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."
My question is (Score:2, Funny)
Suggestion for submitter (Score:4, Insightful)
Please, if discussing a topic that is not widely known, put a short description or definition in the article writeup.
Thanks.
Don't be silly (Score:5, Funny)
Ben
Re:Don't be silly (Score:3, Funny)
Re:Suggestion for submitter (Score:4, Insightful)
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 (Score:5, Insightful)
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...
Re:Suggestion for submitter (Score:3, Informative)
Tag it (Score:5, Insightful)
<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:Tag it (Score:4, Informative)
More pertentely in this context: Slashcode doesn't support it. Even if the original submitter included it in their submission it would have been stripped out before it got to the editors.
Re:Suggestion for submitter (Score:5, Funny)
Thank you.
AOL (Score:4, Funny)
[AOL]
Me Too!
[/AOL]
I publish SPF records (Score:4, Informative)
I've only done the publishing side, I have not yet enabled my mail servers to use them.
Even though SPF may not be a complete or perfect solution, I see no harm in announcing to the world that if it purports to come from my domain than it also comes from my designated mail servers.
Re:I publish SPF records (Score:2)
I think most average users don't really care how it is done, it has become a "just do it" issue.
For websites that need to be able to accept mail from previously unknown senders, a challenge/response shouldn't be a big impediment to the senders as long as they know why it is being done.
Maybe I'm way out in lef
Re:I publish SPF records (Score:4, Funny)
SPF Bad for POBOX's users (Score:3, Interesting)
That's what SASL is for (Score:3, Interesting)
This is often referred to as SASL auth or sometimes SMTP auth.
They probably need to set it up on both port 25 and another port generally 587 in case users ISPs block connections to port 25.
Alternatively there are older solutions that may work for some mail services like POP before send. Where any IP address tha
omg... (Score:2, Informative)
Catching on (Score:3, Interesting)
It appears to be one of these "why didn't I think of that?" solutions that go and take care of a problem without ripping out everything around it.
How about dynamic IPs? (Score:4, Insightful)
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.
Re:How about dynamic IPs? (Score:3, Informative)
In the UK we have plenty of choice for broadband ISPs who offer fixed IPs at no extra cost (which is why I'm moving away from BT Openworld who charge an extra 10 a month for the privilege)
Re:How about dynamic IPs? (Score:3, Informative)
How dynamic are we talking about? (Score:3, Insightful)
And in any event, most dynamic IPs are within a certain net block. so you can simply add that net block to your SPF record. I'm assuming you have your own domain here.
Re:How about dynamic IPs? (Score:3, Interesting)
I hate it when people think stuff is so black and white.
Why this is a big deal (Score:5, Informative)
SPF [pobox.com] 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 [cr.yp.to] and exim [exim.org].
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 [pobox.com].
Re:Why this is a big deal (Score:3, Informative)
Re:Why this is a big deal (Score:2)
Re:Why this is a big deal (Score:5, Informative)
Re:Why this is a big deal (Score:5, Informative)
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 (Score:3, Insightful)
So it was. My mistake.
Re:Why this is a big deal (Score:4, Informative)
However, in order to get things off the ground without having to wait for DNS servers and tools to support a new record type, it is also possible to publish the same information in a TXT record:
If your DNS server supports the SPF *type*, then you should ideally use that and provide the TXT record as a backup. Query tools that properly support SPF will probably look for the SPF type first and then requery for TXT on a failure, but it's up to the developer of course.
anti-spoofing (Score:5, Interesting)
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.
Would someone explain this to a simpleton? (Score:2)
Re:Would someone explain this to a simpleton? (Score:5, Informative)
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.
Re:Would someone explain this to a simpleton? (Score:3, Interesting)
Thank you, carry on.
Some of the benefits. (Score:4, Interesting)
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.
Also stops phishing (Score:3, Interesting)
Re:Some of the benefits. (Score:3, Interesting)
In fact, it makes me wonder if they had a reason to decide against it.
This does reduce spam (Score:5, Informative)
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:This does reduce spam (Score:2)
Why don't you use your ISP's mail relay? That's what it's for. i switched from relaying my mail via my ISP's smtp server to directly sending it to the recipients's MX for one day, and I
Spamassassin will support it in 2.70 (Score:4, Informative)
Anyway, it seems SpamAssassin will be adding support for SPF in 2.70, at least according to bug 2143 [spamassassin.org]. That's cool!
SPF is a really bad idea (Score:2, Interesting)
Are you used to sending personnal email (one that have another domain than your employers in the From: address) from work using your company SMTP server as a relay? You know, the only one you have access to with many reasonable security policies...
Can't do that anymore, your message will be flagged as spam by the recipient server if he checks for SPF records.
Have AOL warned its customers of this little side effect of it implementing SPF?
Plus SPF technically wise sucks, it should have been a new re
Re:SPF is a really bad idea (Score:4, Insightful)
See step 2 on the "How do I implement SPF" [pobox.com] page.
This doesn't help much.... (Score:3, Interesting)
What if I don't have access to the authorized relay, as in all company outgoing mail must go through company SMTP server, wether it as a @company.com from address or a @vanitydomain.com address.
If you read personnal email at work (bad) but keep it separate from your professionnal email (good) this will greatly inconvenience you.
And what about the consultant on a customer's site, if he don't have access to the authorized relay. He can't send mail while still having a perfectly usable SMTP relay at his
Other problems with SPF (Score:5, Interesting)
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.
Re:Other problems with SPF (Score:3, Interesting)
Pay per email? Pay whom, precisely? The ISP? I've already paid them for my subscription. If that is included in a spammers account, their spam gets through. Pay the recipient? Why should I pay you to send you email that isn't spam? Would you give me the cash back? You say that SPF works against the way the internet works, well, the internet is a free-for-all, so why is paying per email NOT against the way the internet works
Re:Other problems with SPF (Score:3, Insightful)
Less annoying then hundreds of SPAMs a week.
* There is a supposedly trusted authentication system being spr
The SPF DoS hole (Score:3, Insightful)
Dynamic IP addresses (Score:3, Informative)
Re:Dynamic IP addresses (Score:4, Informative)
Re:Dynamic IP addresses (Score:2)
SPF lets you specify ranges in CIDR format, so you just need to include the IP pools that the hosts that actually send mail might end up in. Or just set them all to use the ISP's smarthosts and use their static IPs in your domain's SPF records. There's even a very nice wizard [pobox.com] to create your SPF records with and get a feel for what's possible.
How does this protect against zombies? (Score:2)
SASL question (Score:2)
But I also have mail system at work with 25,000 user accounts. I need to get sendmail to auth through the same pam system-auth other services use (it's a complex mix of kerberos with fallback to ldap). A separate sasldb is just not going to cut it in that environment
I think saslauthd is the ti
It does seem to work (Score:4, Informative)
This is what I got:
Jan 8 19:34:01 scrat sendmail[16839]: i08IY0ON016839: Milter: from=<larhondabeirne@aol.com>, reject=550 5.7.1 Command rejected
Jan 9 05:34:47 scrat sendmail[16305]: i094YlON016305: Milter: from=<krbsnag2gs@aol.com>, reject=550 5.7.1 Command rejected
Jan 9 08:59:45 scrat sendmail[25027]: i097xiON025027: Milter: from=<clairacree@aol.com>, reject=550 5.7.1 Command rejected
SPF && DYNDNS (Score:3, Interesting)
Does anyone know how SPF can be managed via dynamice DNS type of DNS services?
It seems to me that having my reverse DNS lookup containing my ISP's domain name rather than mine would help my server configuration. I have a problem with my DNS in that reverse lookups are resolved to a DNS entry, but it belongs to my ISP domain and not my domain name. This gets some people pissy, but I don't see it being worth spending $100 a month extra from my ISP.
Would SPF help this problem? Would I actually be able to gain trust from others? Would DynDNS be able to accomodate this feature? (I'll have to ask them...)
I think a lot of this falls back to a much simply question: Why do we have DHCP addresses on the internet anyways? They do not change. I think mine is about 9 months old. Others tell of greater than a year with the same IP address. I think it would actually help security if people where give static IP addresses. Then they would have to take care of it to ensure they don't act stupid.
Re:SPF && DYNDNS (Score:2)
The simple answer here is this: Limited amount of resources. The same reason we use Dynamic addresses, is the same reason
Re:SPF && DYNDNS (Score:3, Insightful)
Damni! "RMX" was such a cooler acronym! (Score:3, Informative)
and for each bounced message, who knows how many are getting through. A friend of mine (an AOL user) actually had a spammer us his personal email address, and got not only a bunch of bounces, but angry emails and IMs.
The sooner this goes into effect, the better. It'll probably be a long time before we can block all email that doesn't come from a domain with SPF, but hopefully soon we can get rid of emails that are explicitly not authorized. (like those claming to be from my servers...)
I see a problem here.... (Score:5, Insightful)
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.
Re:I see a problem here.... (Score:3, Interesting)
1. Make the customers use Webmail or equivalent when traveling. The mail still originates with your servers.
2. Make the customers VPN to your domain when traveling. The mail is then handled by your servers.
AOL basically does the second, if you connect to them via another service (like AOL High Speed stuff).
I know neither of those are as convenient as "free mail, anywhere, anytime, no q
Re:I see a problem here.... (Score:4, Interesting)
As far as I can understand, your argument boils down to "I don't like SPF because my systems are hideously insecure, I'm cool with them being used as open relays, and I don't feel like being a competent sysadmin"?
AOL will likely remove these SPF records today (Score:5, Informative)
See: this message on the SPF mailing list [gmane.org]
Breaks Forwarding (Score:4, Informative)
Re:boo (Score:5, Informative)
$ 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
Re:boo (Score:2)
; > DiG 9.2.2 > aol.com txt
[...]
A perfect example of why dig is inappropriate for pretty much any task other than debugging BIND. Using host would get you the data you need in a much more sane format:
Re:boo (Score:3, Informative)
G:\>nslookup
> set q=txt
> aol.com
Server: XXXXXXXXXXXXXXX
Address: XXXXXXXXXXXXXXX
Non-authoritative answer:
aol.com text =
"v=spf1 ip4:152.163.225.0/24 ip4:20....
Re:boo (Score:5, Interesting)
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 [scrounger.ath.cx]
Re:boo (Score:3, Informative)
Re:boo (Score:4, Informative)
As to the second point that is already easily dealt with by most intelligent MTA's, heck my ISP's email servers already flag any message which has a different sending IP and host identifier, and they have informed us that they plan to dump the connection on this condition "real soon now". SPF just makes this easier since it can be used to eliminate false positives from semi-clued admins.
Re: (Score:3, Interesting)
Re:boo (Score:2, Insightful)
1) Bandwidth & CPU for additional DNS lookups when people forge mail from their domain.
2) Bandwidth & CPU & staff costs for emails to their customer support desk complaining about the spam. (Bear in mind that the vast majority of users are not savvy enough to know not to complain to AOL.)
Re:boo (Score:2)
As for 2, are you really complaining that delivery of spam would be delayed? It's not as if MTA's usually try to deliver only one message
Re:boo (Score:2, Informative)
(Well okay, it's not quite true. You could just about manage to spoof IPs for machines on the same ethernet segment as you. However, if you're on the same segment as an outbound mail server, you're probably allowed to send via that server anyway.)
Re:Some of us have reasons for spoofing our addres (Score:5, Informative)
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:Some of us have reasons for spoofing our addres (Score:2, Informative)
You wouldn't. But that is part of the problem as legitimate uses can't be differentiated from SPAM when taking this approach.
Its one of those great "lose liberty in the name of enforcement" style things.
Or of course you could just set up SMTP on that remote server of yours.
Not true (Score:2)
Re:Some of us have reasons for spoofing our addres (Score:2)
Re: (Score:3, Insightful)
Re:Linis Torvald Troll (Score:2)
Re:Some of us have reasons for spoofing our addres (Score:2)
Sign your messages with PGP so that everyone knows it's really you, whatever address the mail comes from. AFAIK all mail clients automatically use the reply-to field when someone replies to your message.
SPF is NOT a problem for you, (Score:5, Informative)
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?
Re:How does this reduce spam in any shape or form? (Score:2, Informative)
1) since it effectively kills sender forgeries, it's a LOT easier to maintain white/blacklists
2) a domain needs to be purchased, and the registration takes time; this increases the cost of spam and hopefully might also make spammers more traceable (credit card transactions for registration)
I am totally convinced this will make the spam problem manageable. I'll probably add my own SPF this weekend.
Re:How does this reduce spam in any shape or form? (Score:5, Interesting)
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? (Score:5, Interesting)
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 [nsa.co.il] which has a nice SPF plugin).
Re:How does this reduce spam in any shape or form? (Score:3, Interesting)
Re:How does this reduce spam in any shape or form? (Score:5, Informative)
I bet your parents are proud!
Re:How does this reduce spam in any shape or form? (Score:2)
Ticking the 'do not want to moderate box' right now. It's of no use with so many ignorant people.
Thanks for your vigilance.
jdif
Re:How does this reduce spam in any shape or form? (Score:2)
Re:How does this reduce spam in any shape or form? (Score:2)
Re:How does this reduce spam in any shape or form? (Score:2)
Boo hoo a mail admin will have to take the hour or two it takes to properly implement SASL and you will have to roll out a change to the corporate email client that defaults it to talking SASL. Besides most remote users use VPN these days anyways. Also if all the big guys implement it and implement serious negative scoring for those not using it then it will quickly be adopted by those with a clue, those without a c
Re:How does this reduce spam in any shape or form? (Score:3, Insightful)
2) Zombie virus-infected mail relay clients
etc
It makes whitelists work better (Score:3, Insightful)
You may even want to use a whitelist server ran by someone you trust.
Re:How does this reduce spam in any shape or form? (Score:2)
As for people on the road, they should have access to a VPN setup or to connect to a password protected corporate smarthost if they want to send e-mail with the corporate from address. It's not as if it's
Re:Observe the missing link (Score:3, Insightful)
of course you are right, but mods must understand too that a post must not be modded up because it seems clever, or because it repeats something clever someone already said before.
I can cite my Oreilly's books all day if I want to. Beyond the awkward morality of such guys (you can criticize /., but the best thing is to do it correctly), this brings nothing.
Repeating what you can learn by making your head work for 10 secs, it's ok. I'm not here for that.
Regards,
jdif
Re:This is a good idea (Score:2)
Actually, when you set the default search domain to the ISP you are dialling in to and fix the SMTP server to "smtp", this usually works.
Setting the search domain is easy when you get your address using DHCP, and could be done in an ip-up script in other situations.
Get a business line (Score:2)
Blocking port 25 on dynamic IPs is perfectly reasonable. If you're running a legitimate mail server you can easily get to it without making your ISP that blocks port 25 li
Re:Get a business line (Score:2)
Re:This is a good idea (Score:3, Insightful)
Actually, that wouldn't work -- other SMTP servers have no way of knowing which port your SMTP server will be on, so it is hardwired to port 25. You wouldn't be able to receive any e-mail.
Re:interesting blog. djbdns? (Score:2)
From what I can see of SPF, it's just a matter of setting up the TXT record in DNS.
rbldns [cr.yp.to] does it in djbdns.
Comment removed (Score:4, Informative)
Re:The really important question is... (Score:3, Informative)
As a matter of fact, there is nothing stopping spammers from registering a bogus domain, and making the entire internet part of their SPF
But it kills domain forging; they have to use their own bogus domains which can be quickly and easily blacklisted by other methods if they spam a lot. SPF says "This machine can be held accountable for mail sent for this domain," there's no magic if you're not willing to actually hold people accountable. But the contrapositive to that is, if someone says they're host