Re: OSF for an ISP (was Re: ..idea; ddos spam hosts off Internet?)

2004-04-10 Thread Arnt Karlsen
On Sat, 10 Apr 2004 11:45:38 +1300, Pulu wrote in message 
<[EMAIL PROTECTED]>:

> To kind of get back to the ISP world a little bit, has anyone used
> this in the way that's being recommended?  (Using the OS Fingerprint
> Netfilter patch to block Windows machines sending to port 25).

..and then trap them in a tarpit server outside your current gateway?
I see no reason to let spammers tie up ip_conntrack entries, they 
should be sunk in a tarpit.

-- 
..med vennlig hilsen = with Kind Regards from Arnt... ;-)
...with a number of polar bear hunters in his ancestry...
  Scenarios always come in sets of three: 
  best case, worst case, and just in case.





Re: OSF for an ISP (was Re: ..idea; ddos spam hosts off Internet?)

2004-04-10 Thread Arnt Karlsen
On Sat, 10 Apr 2004 11:45:38 +1300, Pulu wrote in message 
<[EMAIL PROTECTED]>:

> To kind of get back to the ISP world a little bit, has anyone used
> this in the way that's being recommended?  (Using the OS Fingerprint
> Netfilter patch to block Windows machines sending to port 25).

..and then trap them in a tarpit server outside your current gateway?
I see no reason to let spammers tie up ip_conntrack entries, they 
should be sunk in a tarpit.

-- 
..med vennlig hilsen = with Kind Regards from Arnt... ;-)
...with a number of polar bear hunters in his ancestry...
  Scenarios always come in sets of three: 
  best case, worst case, and just in case.



-- 
To UNSUBSCRIBE, email to [EMAIL PROTECTED]
with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]



Re: OSF for an ISP (was Re: ..idea; ddos spam hosts off Internet?)

2004-04-10 Thread Christian Storch
- Original Message - 
From: "Russell Coker" <[EMAIL PROTECTED]>
To: 
Cc: "Pulu 'Anau" <[EMAIL PROTECTED]>
Sent: Saturday, April 10, 2004 3:12 PM
Subject: Re: OSF for an ISP (was Re: ..idea; ddos spam hosts off Internet?)


> For NT (XP etc) you could allow every fourth day for receiving mail.  Mail is 
> generally queued for four days before being bounced, so if you only accept 
> mail from NT machines every fourth day then you lose 75% of the spam and 
> viruses because spam proxies and viruses generally don't re-try.  Legit mail 
> servers will keep trying until you let them through.
> 
> Avoiding 75% of the spam and viruses isn't a solution to the problem, but 
> it's 
> a good start...
> 

Have a look at http://www.greylisting.org/ and you could avoid much more spam
while reducing false positives to nearly zero!

Christian





Re: OSF for an ISP (was Re: ..idea; ddos spam hosts off Internet?)

2004-04-10 Thread Russell Coker
On Sat, 10 Apr 2004 08:45, Pulu 'Anau <[EMAIL PROTECTED]> wrote:
> To kind of get back to the ISP world a little bit, has anyone used this in
> the way that's being recommended?  (Using the OS Fingerprint Netfilter
> patch to block Windows machines sending to port 25).
>
> We're currently getting slammed by Windows viruses and have thought about
> doing exactly that, but it seemed to us that there are enough people using
> Exchange or Sendmail.com's windows sendmail (let alone ftgate, etc, etc.)
> that doing this would block legitimate mail almost instantly.

Is there any legit mail server software for Win98?  If not then you can 
permanently block it.

For NT (XP etc) you could allow every fourth day for receiving mail.  Mail is 
generally queued for four days before being bounced, so if you only accept 
mail from NT machines every fourth day then you lose 75% of the spam and 
viruses because spam proxies and viruses generally don't re-try.  Legit mail 
servers will keep trying until you let them through.

Avoiding 75% of the spam and viruses isn't a solution to the problem, but it's 
a good start...

-- 
http://www.coker.com.au/selinux/   My NSA Security Enhanced Linux packages
http://www.coker.com.au/bonnie++/  Bonnie++ hard drive benchmark
http://www.coker.com.au/postal/Postal SMTP/POP benchmark
http://www.coker.com.au/~russell/  My home page




Re: OSF for an ISP (was Re: ..idea; ddos spam hosts off Internet?)

2004-04-10 Thread Christian Storch
- Original Message - 
From: "Russell Coker" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Cc: "Pulu 'Anau" <[EMAIL PROTECTED]>
Sent: Saturday, April 10, 2004 3:12 PM
Subject: Re: OSF for an ISP (was Re: ..idea; ddos spam hosts off Internet?)


> For NT (XP etc) you could allow every fourth day for receiving mail.  Mail is 
> generally queued for four days before being bounced, so if you only accept 
> mail from NT machines every fourth day then you lose 75% of the spam and 
> viruses because spam proxies and viruses generally don't re-try.  Legit mail 
> servers will keep trying until you let them through.
> 
> Avoiding 75% of the spam and viruses isn't a solution to the problem, but it's 
> a good start...
> 

Have a look at http://www.greylisting.org/ and you could avoid much more spam
while reducing false positives to nearly zero!

Christian



-- 
To UNSUBSCRIBE, email to [EMAIL PROTECTED]
with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]



Re: OSF for an ISP (was Re: ..idea; ddos spam hosts off Internet?)

2004-04-10 Thread Russell Coker
On Sat, 10 Apr 2004 08:45, Pulu 'Anau <[EMAIL PROTECTED]> wrote:
> To kind of get back to the ISP world a little bit, has anyone used this in
> the way that's being recommended?  (Using the OS Fingerprint Netfilter
> patch to block Windows machines sending to port 25).
>
> We're currently getting slammed by Windows viruses and have thought about
> doing exactly that, but it seemed to us that there are enough people using
> Exchange or Sendmail.com's windows sendmail (let alone ftgate, etc, etc.)
> that doing this would block legitimate mail almost instantly.

Is there any legit mail server software for Win98?  If not then you can 
permanently block it.

For NT (XP etc) you could allow every fourth day for receiving mail.  Mail is 
generally queued for four days before being bounced, so if you only accept 
mail from NT machines every fourth day then you lose 75% of the spam and 
viruses because spam proxies and viruses generally don't re-try.  Legit mail 
servers will keep trying until you let them through.

Avoiding 75% of the spam and viruses isn't a solution to the problem, but it's 
a good start...

-- 
http://www.coker.com.au/selinux/   My NSA Security Enhanced Linux packages
http://www.coker.com.au/bonnie++/  Bonnie++ hard drive benchmark
http://www.coker.com.au/postal/Postal SMTP/POP benchmark
http://www.coker.com.au/~russell/  My home page


-- 
To UNSUBSCRIBE, email to [EMAIL PROTECTED]
with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]



Re: OSF for an ISP (was Re: ..idea; ddos spam hosts off Internet?)

2004-04-10 Thread Ralph Paßgang
Hi,

you shouldn't try to block everything that comes from a host which has no open 
smtp port, this is in generel a bad idea...

reason: there are a lot (and I mean a lot) of servers out there, which only 
sends mail out to the world, but should never recieve any mail directly, so 
that it is okay to bind the smtpd only to localhost or to a internal lan 
interface. Often there are other servers which recieves the mail for these 
kind of setups...

The better way is to check against a real blacklist which has entries for 
dial-up networks and maybe for dns-names without any MX or A entry...

for example spamassassin asks a lot of real blacklists and so it also checks 
these things:

example  for checks against RBLs (sorry, it's a german system, but I will 
translate):

- NO_DNS_FOR_FROM:
Domain der Absendeadresse nicht im DNS registriert (kein MX/A Eintrag) / 
Domain of the sendingaddress has no dns entry (no mx/a record)

- RCVD_IN_NJABL_DIALUP RBL: NJABL: 
Senderechner nur temporär mit Internet verbunden [XXX.XXX.XXX.XXX listed in 
dnsbl.njabl.org] / Sending host is only connected to the internet temporary 
(dial up)

and so on So in my opinion it's better to check against such lists than 
simply block all mail that comes from a system without open smtp...

--Ralph

Am Samstag 10 April 2004 01:18 schrieb Andreas John:
> Hi!
>
> Dave Watkins wrote:
> > If I remember right (and someone correct me if I'm wrong) a mail server
> > doesn't have to have an MX record. If no MX record exists then the
> > sending server drops back to normal host records and this is perfectly
> > legitimate. So the MX record checking may not work so well
>
> Dave, your theory is right, you don't have to have an MX record in your
> DNS zone in order to receive mail, but Pulu wants to "tcpping", so his
> idea is to check if there is an open port 25, i.e. check if the sending
> server is an mailserver. This would not be the case with infected
> outlooks ;) but also not for hosts behind NAT FW.
> @Pulu: Is that your idea?
>
> The problem is more that a sending host has not neccessarily to be an
> receiver. (remindes me on goatse.cx ;-)) nor that is has to be smtp
> (submission et al?)
>
> In Germany several large scale ISPs began to block all mail comming
> directly from an dialup ip, so I think it would be an accepted way to
> try what Pulu wants to do.
>
> Rgds,
> j.
>
>
>
>
> --
> Andreas John
> net-lab GmbH
> Luisenstrasse 30b
> 63067 Offenbach
> Tel: +49 69 85700331
>
> http://www.net-lab.net




Re: OSF for an ISP (was Re: ..idea; ddos spam hosts off Internet?)

2004-04-10 Thread Ralph Paßgang
Hi,

you shouldn't try to block everything that comes from a host which has no open 
smtp port, this is in generel a bad idea...

reason: there are a lot (and I mean a lot) of servers out there, which only 
sends mail out to the world, but should never recieve any mail directly, so 
that it is okay to bind the smtpd only to localhost or to a internal lan 
interface. Often there are other servers which recieves the mail for these 
kind of setups...

The better way is to check against a real blacklist which has entries for 
dial-up networks and maybe for dns-names without any MX or A entry...

for example spamassassin asks a lot of real blacklists and so it also checks 
these things:

example  for checks against RBLs (sorry, it's a german system, but I will 
translate):

- NO_DNS_FOR_FROM:
Domain der Absendeadresse nicht im DNS registriert (kein MX/A Eintrag) / 
Domain of the sendingaddress has no dns entry (no mx/a record)

- RCVD_IN_NJABL_DIALUP RBL: NJABL: 
Senderechner nur temporär mit Internet verbunden [XXX.XXX.XXX.XXX listed in 
dnsbl.njabl.org] / Sending host is only connected to the internet temporary 
(dial up)

and so on So in my opinion it's better to check against such lists than 
simply block all mail that comes from a system without open smtp...

--Ralph

Am Samstag 10 April 2004 01:18 schrieb Andreas John:
> Hi!
>
> Dave Watkins wrote:
> > If I remember right (and someone correct me if I'm wrong) a mail server
> > doesn't have to have an MX record. If no MX record exists then the
> > sending server drops back to normal host records and this is perfectly
> > legitimate. So the MX record checking may not work so well
>
> Dave, your theory is right, you don't have to have an MX record in your
> DNS zone in order to receive mail, but Pulu wants to "tcpping", so his
> idea is to check if there is an open port 25, i.e. check if the sending
> server is an mailserver. This would not be the case with infected
> outlooks ;) but also not for hosts behind NAT FW.
> @Pulu: Is that your idea?
>
> The problem is more that a sending host has not neccessarily to be an
> receiver. (remindes me on goatse.cx ;-)) nor that is has to be smtp
> (submission et al?)
>
> In Germany several large scale ISPs began to block all mail comming
> directly from an dialup ip, so I think it would be an accepted way to
> try what Pulu wants to do.
>
> Rgds,
> j.
>
>
>
>
> --
> Andreas John
> net-lab GmbH
> Luisenstrasse 30b
> 63067 Offenbach
> Tel: +49 69 85700331
>
> http://www.net-lab.net



Re: OSF for an ISP (was Re: ..idea; ddos spam hosts off Internet?)

2004-04-09 Thread Andreas John
Hi!
Dave Watkins wrote:
If I remember right (and someone correct me if I'm wrong) a mail server 
doesn't have to have an MX record. If no MX record exists then the 
sending server drops back to normal host records and this is perfectly 
legitimate. So the MX record checking may not work so well
Dave, your theory is right, you don't have to have an MX record in your 
DNS zone in order to receive mail, but Pulu wants to "tcpping", so his 
idea is to check if there is an open port 25, i.e. check if the sending 
server is an mailserver. This would not be the case with infected 
outlooks ;) but also not for hosts behind NAT FW.
@Pulu: Is that your idea?

The problem is more that a sending host has not neccessarily to be an
receiver. (remindes me on goatse.cx ;-)) nor that is has to be smtp 
(submission et al?)

In Germany several large scale ISPs began to block all mail comming 
directly from an dialup ip, so I think it would be an accepted way to 
try what Pulu wants to do.

Rgds,
j.

--
Andreas John
net-lab GmbH
Luisenstrasse 30b
63067 Offenbach
Tel: +49 69 85700331
http://www.net-lab.net



Re: OSF for an ISP (was Re: ..idea; ddos spam hosts off Internet?)

2004-04-09 Thread Dave Watkins
If I remember right (and someone correct me if I'm wrong) a mail server 
doesn't have to have an MX record. If no MX record exists then the 
sending server drops back to normal host records and this is perfectly 
legitimate. So the MX record checking may not work so well

Pulu 'Anau wrote:
To kind of get back to the ISP world a little bit, has anyone used this in the
way that's being recommended?  (Using the OS Fingerprint Netfilter patch to
block Windows machines sending to port 25).
We're currently getting slammed by Windows viruses and have thought about doing
exactly that, but it seemed to us that there are enough people using Exchange or
Sendmail.com's windows sendmail (let alone ftgate, etc, etc.) that doing this
would block legitimate mail almost instantly.
We've just been blocking hosts manually after the first virus.  I'm thinking
about writing a little script to:
1.  Get the offending IP address from amavis's logfile
2.  Check against a whitelist (like our own backup mx's)
3.  Do something like tcpping to the IP to see if it is a valid mx host
4.  If it doesn't pass checks 2 or 3, block the IP in netfilter for 72 hours
Other than the 72 hour checks it's pretty straightforward and seems (at least to
me) very unlikely to stop legitimate mail, while cutting those guys who send
40-50 viruses a day down to 1 every three.  

Does anyone see any problems with the above?  The major issue is bandwidth, some
of our customers host their mail servers on 32K links with 200+ users.
Sorry, it's not really about the spam issue discussed before, but it's strange
the synchronicity (os fingerprinting anyway) between my work and this list
sometimes.
Pulu

Afe.to ANTS
POB 1478
Nuku'alofa, Tonga
Ph: Country code 676 - 27946 or 878-1332
http://www.afe.to
http://svcs.affero.net/rm.php?r=pulu
Quoting Russell Coker <[EMAIL PROTECTED]>:
 

On Fri, 9 Apr 2004 21:32, Arnt Karlsen <[EMAIL PROTECTED]> wrote:
   

On Fri, 9 Apr 2004 15:27:03 +1000, Russell wrote in message
 

http://www.netfilter.org/patch-o-matic/pom-base.html
See the section on "osf" in the above URL for a better solution.
Simply block Windows machines from accessing your port 25.
   

..if only all isp's did it...
 

Not all ISPs need to do it.  Only your ISP and the ISPs that host mailing 
lists that you subscribe to.

If you are interested in this then the best thing you can do is to build 
yourself a kernel with osf and try it out.  If it works well create a Debian

kernel-patch package for it so that other Debian users can conveniently use
it.  The more accessible you make this to Debian people the closer it comes
to being installed on Debian list servers...
--
http://www.coker.com.au/selinux/   My NSA Security Enhanced Linux packages
http://www.coker.com.au/bonnie++/  Bonnie++ hard drive benchmark
http://www.coker.com.au/postal/Postal SMTP/POP benchmark
http://www.coker.com.au/~russell/  My home page
--
To UNSUBSCRIBE, email to [EMAIL PROTECTED]
with a subject of "unsubscribe". Trouble? Contact
[EMAIL PROTECTED]
   


-
This mail sent from Tonga's Premiere Internet Cafe
Visit us online at http://www.cafe.afe.to 
discussions @ http://www.nomoa.com/index.php
generic info @  http://www.tongatapu.net.to

 




OSF for an ISP (was Re: ..idea; ddos spam hosts off Internet?)

2004-04-09 Thread Pulu 'Anau
To kind of get back to the ISP world a little bit, has anyone used this in the
way that's being recommended?  (Using the OS Fingerprint Netfilter patch to
block Windows machines sending to port 25).

We're currently getting slammed by Windows viruses and have thought about doing
exactly that, but it seemed to us that there are enough people using Exchange or
Sendmail.com's windows sendmail (let alone ftgate, etc, etc.) that doing this
would block legitimate mail almost instantly.

We've just been blocking hosts manually after the first virus.  I'm thinking
about writing a little script to:

1.  Get the offending IP address from amavis's logfile
2.  Check against a whitelist (like our own backup mx's)
3.  Do something like tcpping to the IP to see if it is a valid mx host
4.  If it doesn't pass checks 2 or 3, block the IP in netfilter for 72 hours

Other than the 72 hour checks it's pretty straightforward and seems (at least to
me) very unlikely to stop legitimate mail, while cutting those guys who send
40-50 viruses a day down to 1 every three.  

Does anyone see any problems with the above?  The major issue is bandwidth, some
of our customers host their mail servers on 32K links with 200+ users.

Sorry, it's not really about the spam issue discussed before, but it's strange
the synchronicity (os fingerprinting anyway) between my work and this list
sometimes.

Pulu


Afe.to ANTS
POB 1478
Nuku'alofa, Tonga
Ph: Country code 676 - 27946 or 878-1332
http://www.afe.to
http://svcs.affero.net/rm.php?r=pulu


Quoting Russell Coker <[EMAIL PROTECTED]>:

> On Fri, 9 Apr 2004 21:32, Arnt Karlsen <[EMAIL PROTECTED]> wrote:
> > On Fri, 9 Apr 2004 15:27:03 +1000, Russell wrote in message
> > > http://www.netfilter.org/patch-o-matic/pom-base.html
> > >
> > > See the section on "osf" in the above URL for a better solution.
> > > Simply block Windows machines from accessing your port 25.
> >
> > ..if only all isp's did it...
> 
> Not all ISPs need to do it.  Only your ISP and the ISPs that host mailing 
> lists that you subscribe to.
> 
> If you are interested in this then the best thing you can do is to build 
> yourself a kernel with osf and try it out.  If it works well create a Debian
> 
> kernel-patch package for it so that other Debian users can conveniently use
> 
> it.  The more accessible you make this to Debian people the closer it comes
> 
> to being installed on Debian list servers...
> 
> -- 
> http://www.coker.com.au/selinux/   My NSA Security Enhanced Linux packages
> http://www.coker.com.au/bonnie++/  Bonnie++ hard drive benchmark
> http://www.coker.com.au/postal/Postal SMTP/POP benchmark
> http://www.coker.com.au/~russell/  My home page
> 
> 
> -- 
> To UNSUBSCRIBE, email to [EMAIL PROTECTED]
> with a subject of "unsubscribe". Trouble? Contact
> [EMAIL PROTECTED]
> 


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This mail sent from Tonga's Premiere Internet Cafe
Visit us online at http://www.cafe.afe.to 
discussions @ http://www.nomoa.com/index.php
generic info @  http://www.tongatapu.net.to




Re: OSF for an ISP (was Re: ..idea; ddos spam hosts off Internet?)

2004-04-09 Thread Andreas John
Hi!

Dave Watkins wrote:
If I remember right (and someone correct me if I'm wrong) a mail server 
doesn't have to have an MX record. If no MX record exists then the 
sending server drops back to normal host records and this is perfectly 
legitimate. So the MX record checking may not work so well
Dave, your theory is right, you don't have to have an MX record in your 
DNS zone in order to receive mail, but Pulu wants to "tcpping", so his 
idea is to check if there is an open port 25, i.e. check if the sending 
server is an mailserver. This would not be the case with infected 
outlooks ;) but also not for hosts behind NAT FW.
@Pulu: Is that your idea?

The problem is more that a sending host has not neccessarily to be an
receiver. (remindes me on goatse.cx ;-)) nor that is has to be smtp 
(submission et al?)

In Germany several large scale ISPs began to block all mail comming 
directly from an dialup ip, so I think it would be an accepted way to 
try what Pulu wants to do.

Rgds,
j.


--
Andreas John
net-lab GmbH
Luisenstrasse 30b
63067 Offenbach
Tel: +49 69 85700331
http://www.net-lab.net

--
To UNSUBSCRIBE, email to [EMAIL PROTECTED]
with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]


Re: OSF for an ISP (was Re: ..idea; ddos spam hosts off Internet?)

2004-04-09 Thread Dave Watkins
If I remember right (and someone correct me if I'm wrong) a mail server 
doesn't have to have an MX record. If no MX record exists then the 
sending server drops back to normal host records and this is perfectly 
legitimate. So the MX record checking may not work so well

Pulu 'Anau wrote:

To kind of get back to the ISP world a little bit, has anyone used this in the
way that's being recommended?  (Using the OS Fingerprint Netfilter patch to
block Windows machines sending to port 25).
We're currently getting slammed by Windows viruses and have thought about doing
exactly that, but it seemed to us that there are enough people using Exchange or
Sendmail.com's windows sendmail (let alone ftgate, etc, etc.) that doing this
would block legitimate mail almost instantly.
We've just been blocking hosts manually after the first virus.  I'm thinking
about writing a little script to:
1.  Get the offending IP address from amavis's logfile
2.  Check against a whitelist (like our own backup mx's)
3.  Do something like tcpping to the IP to see if it is a valid mx host
4.  If it doesn't pass checks 2 or 3, block the IP in netfilter for 72 hours
Other than the 72 hour checks it's pretty straightforward and seems (at least to
me) very unlikely to stop legitimate mail, while cutting those guys who send
40-50 viruses a day down to 1 every three.  

Does anyone see any problems with the above?  The major issue is bandwidth, some
of our customers host their mail servers on 32K links with 200+ users.
Sorry, it's not really about the spam issue discussed before, but it's strange
the synchronicity (os fingerprinting anyway) between my work and this list
sometimes.
Pulu


Afe.to ANTS
POB 1478
Nuku'alofa, Tonga
Ph: Country code 676 - 27946 or 878-1332
http://www.afe.to
http://svcs.affero.net/rm.php?r=pulu
Quoting Russell Coker <[EMAIL PROTECTED]>:

 

On Fri, 9 Apr 2004 21:32, Arnt Karlsen <[EMAIL PROTECTED]> wrote:
   

On Fri, 9 Apr 2004 15:27:03 +1000, Russell wrote in message
 

http://www.netfilter.org/patch-o-matic/pom-base.html

See the section on "osf" in the above URL for a better solution.
Simply block Windows machines from accessing your port 25.
   

..if only all isp's did it...
 

Not all ISPs need to do it.  Only your ISP and the ISPs that host mailing 
lists that you subscribe to.

If you are interested in this then the best thing you can do is to build 
yourself a kernel with osf and try it out.  If it works well create a Debian

kernel-patch package for it so that other Debian users can conveniently use

it.  The more accessible you make this to Debian people the closer it comes

to being installed on Debian list servers...

--
http://www.coker.com.au/selinux/   My NSA Security Enhanced Linux packages
http://www.coker.com.au/bonnie++/  Bonnie++ hard drive benchmark
http://www.coker.com.au/postal/Postal SMTP/POP benchmark
http://www.coker.com.au/~russell/  My home page
--
To UNSUBSCRIBE, email to [EMAIL PROTECTED]
with a subject of "unsubscribe". Trouble? Contact
[EMAIL PROTECTED]
   



-
This mail sent from Tonga's Premiere Internet Cafe
Visit us online at http://www.cafe.afe.to 
discussions @ http://www.nomoa.com/index.php
generic info @  http://www.tongatapu.net.to

 



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OSF for an ISP (was Re: ..idea; ddos spam hosts off Internet?)

2004-04-09 Thread Pulu 'Anau
To kind of get back to the ISP world a little bit, has anyone used this in the
way that's being recommended?  (Using the OS Fingerprint Netfilter patch to
block Windows machines sending to port 25).

We're currently getting slammed by Windows viruses and have thought about doing
exactly that, but it seemed to us that there are enough people using Exchange or
Sendmail.com's windows sendmail (let alone ftgate, etc, etc.) that doing this
would block legitimate mail almost instantly.

We've just been blocking hosts manually after the first virus.  I'm thinking
about writing a little script to:

1.  Get the offending IP address from amavis's logfile
2.  Check against a whitelist (like our own backup mx's)
3.  Do something like tcpping to the IP to see if it is a valid mx host
4.  If it doesn't pass checks 2 or 3, block the IP in netfilter for 72 hours

Other than the 72 hour checks it's pretty straightforward and seems (at least to
me) very unlikely to stop legitimate mail, while cutting those guys who send
40-50 viruses a day down to 1 every three.  

Does anyone see any problems with the above?  The major issue is bandwidth, some
of our customers host their mail servers on 32K links with 200+ users.

Sorry, it's not really about the spam issue discussed before, but it's strange
the synchronicity (os fingerprinting anyway) between my work and this list
sometimes.

Pulu


Afe.to ANTS
POB 1478
Nuku'alofa, Tonga
Ph: Country code 676 - 27946 or 878-1332
http://www.afe.to
http://svcs.affero.net/rm.php?r=pulu


Quoting Russell Coker <[EMAIL PROTECTED]>:

> On Fri, 9 Apr 2004 21:32, Arnt Karlsen <[EMAIL PROTECTED]> wrote:
> > On Fri, 9 Apr 2004 15:27:03 +1000, Russell wrote in message
> > > http://www.netfilter.org/patch-o-matic/pom-base.html
> > >
> > > See the section on "osf" in the above URL for a better solution.
> > > Simply block Windows machines from accessing your port 25.
> >
> > ..if only all isp's did it...
> 
> Not all ISPs need to do it.  Only your ISP and the ISPs that host mailing 
> lists that you subscribe to.
> 
> If you are interested in this then the best thing you can do is to build 
> yourself a kernel with osf and try it out.  If it works well create a Debian
> 
> kernel-patch package for it so that other Debian users can conveniently use
> 
> it.  The more accessible you make this to Debian people the closer it comes
> 
> to being installed on Debian list servers...
> 
> -- 
> http://www.coker.com.au/selinux/   My NSA Security Enhanced Linux packages
> http://www.coker.com.au/bonnie++/  Bonnie++ hard drive benchmark
> http://www.coker.com.au/postal/Postal SMTP/POP benchmark
> http://www.coker.com.au/~russell/  My home page
> 
> 
> -- 
> To UNSUBSCRIBE, email to [EMAIL PROTECTED]
> with a subject of "unsubscribe". Trouble? Contact
> [EMAIL PROTECTED]
> 


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Re: ..idea; ddos spam hosts off Internet?

2004-04-09 Thread Arnt Karlsen
On Fri, 9 Apr 2004 22:53:15 +1000, Russell wrote in message 
<[EMAIL PROTECTED]>:

> On Fri, 9 Apr 2004 21:32, Arnt Karlsen <[EMAIL PROTECTED]> wrote:
> > On Fri, 9 Apr 2004 15:27:03 +1000, Russell wrote in message
> > > http://www.netfilter.org/patch-o-matic/pom-base.html
> > >
> > > See the section on "osf" in the above URL for a better solution.
> > > Simply block Windows machines from accessing your port 25.
> >
> > ..if only all isp's did it...
> 
> Not all ISPs need to do it.  Only your ISP and the ISPs that host
> mailing lists that you subscribe to.

..true.  And, it does nothing to stop Bill Gates' email-fee scheme.

> If you are interested in this then the best thing you can do is to
> build yourself a kernel with osf and try it out.  If it works well
> create a Debian kernel-patch package for it so that other Debian users
> can conveniently use it.  The more accessible you make this to Debian
> people the closer it comes to being installed on Debian list
> servers...

..I agree, but don't hold your breath, I'm still a fresh Red Hat 
convertee, and I first have to get apt-get or yum up and going 
on my client's boxes, ie; those RH-7.3 and RH-9'ers that I need 
to keep up 24/7, everything else is and becomes Woody and 
Sarge as soon as they blink.  ;-)  I'll honk the horn when my 
osf deb needs testing.

-- 
..med vennlig hilsen = with Kind Regards from Arnt... ;-)
...with a number of polar bear hunters in his ancestry...
  Scenarios always come in sets of three: 
  best case, worst case, and just in case.





Re: ..idea; ddos spam hosts off Internet?

2004-04-09 Thread Russell Coker
On Fri, 9 Apr 2004 21:32, Arnt Karlsen <[EMAIL PROTECTED]> wrote:
> On Fri, 9 Apr 2004 15:27:03 +1000, Russell wrote in message
> > http://www.netfilter.org/patch-o-matic/pom-base.html
> >
> > See the section on "osf" in the above URL for a better solution.
> > Simply block Windows machines from accessing your port 25.
>
> ..if only all isp's did it...

Not all ISPs need to do it.  Only your ISP and the ISPs that host mailing 
lists that you subscribe to.

If you are interested in this then the best thing you can do is to build 
yourself a kernel with osf and try it out.  If it works well create a Debian 
kernel-patch package for it so that other Debian users can conveniently use 
it.  The more accessible you make this to Debian people the closer it comes 
to being installed on Debian list servers...

-- 
http://www.coker.com.au/selinux/   My NSA Security Enhanced Linux packages
http://www.coker.com.au/bonnie++/  Bonnie++ hard drive benchmark
http://www.coker.com.au/postal/Postal SMTP/POP benchmark
http://www.coker.com.au/~russell/  My home page




Re: ..idea; ddos spam hosts off Internet?

2004-04-09 Thread Arnt Karlsen
On Fri, 9 Apr 2004 22:53:15 +1000, Russell wrote in message 
<[EMAIL PROTECTED]>:

> On Fri, 9 Apr 2004 21:32, Arnt Karlsen <[EMAIL PROTECTED]> wrote:
> > On Fri, 9 Apr 2004 15:27:03 +1000, Russell wrote in message
> > > http://www.netfilter.org/patch-o-matic/pom-base.html
> > >
> > > See the section on "osf" in the above URL for a better solution.
> > > Simply block Windows machines from accessing your port 25.
> >
> > ..if only all isp's did it...
> 
> Not all ISPs need to do it.  Only your ISP and the ISPs that host
> mailing lists that you subscribe to.

..true.  And, it does nothing to stop Bill Gates' email-fee scheme.

> If you are interested in this then the best thing you can do is to
> build yourself a kernel with osf and try it out.  If it works well
> create a Debian kernel-patch package for it so that other Debian users
> can conveniently use it.  The more accessible you make this to Debian
> people the closer it comes to being installed on Debian list
> servers...

..I agree, but don't hold your breath, I'm still a fresh Red Hat 
convertee, and I first have to get apt-get or yum up and going 
on my client's boxes, ie; those RH-7.3 and RH-9'ers that I need 
to keep up 24/7, everything else is and becomes Woody and 
Sarge as soon as they blink.  ;-)  I'll honk the horn when my 
osf deb needs testing.

-- 
..med vennlig hilsen = with Kind Regards from Arnt... ;-)
...with a number of polar bear hunters in his ancestry...
  Scenarios always come in sets of three: 
  best case, worst case, and just in case.



-- 
To UNSUBSCRIBE, email to [EMAIL PROTECTED]
with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]



Re: ..idea; ddos spam hosts off Internet?

2004-04-09 Thread Arnt Karlsen
On Fri, 9 Apr 2004 15:27:03 +1000, Russell wrote in message 
<[EMAIL PROTECTED]>:

> On Fri, 9 Apr 2004 09:51, Arnt Karlsen <[EMAIL PROTECTED]> wrote:
> > ..another idea; DDOS'ing spam hosts _off_ the net, say by using
> > other spam hosts as DOS relays?  Spam headers contain the
> > originating ip, and 2 such _can_ be set up to DOS each other. 
> > _Etc_.
> 
> The problem is that such attacks are a crime, and you are probably
> easier for the authorities to catch then the spammer...

..most places, agreed.

> > ..these spam hosts are commonly virus infected Wintendo's without
> > the owner knowing, as such unsuspecting owners feel their box
> > appears to work normally.
> >
> > ..these virus infected Wintendos should be taken off-line, anyway,
> > and made secure. And isp's should have a policy on such abuse,
> > and enforce it.
> 
> http://www.netfilter.org/patch-o-matic/pom-base.html
> 
> See the section on "osf" in the above URL for a better solution. 
> Simply block Windows machines from accessing your port 25.

..if only all isp's did it...

> > ..outside Internet, similar action is warranted in many
> > jurisdictions, by laws governing emergencies, for example, breaking
> > into your neighbors house to take his computer is a criminal
> > offence, but may be warranted if his house is ablaze and you know
> > the loss of his data will destroy his business.
> 
> I doubt that any court would rule that a DDOS attack is lawful,
> particularly as the attack would mostly harm an innocent ISP that has
> a Windows luser as a customer (all ISPs have lame customers).

..argueably, yes, however in the case of the lame isp's, 
there's possibly an opening for such court rulings. 

> > ..Bill Gates' proposal of email-for-a-fee-to-Microsoft to solve
> > this, is IMHO pure racism, as is Nigeria's 419 legislation, as it
> > effectively denies all other Africans and many Asians the access to
> > the free email that you and I enjoy.
> 
> I don't want to send email to Microsoft anyway...  ;)

.. ;-)  The Microsoft scheme is a M$ scheme, their idea is 
collect the M$ thru their "passport" "service", AFAIUI.

..and, booo, you cc'ed me, spammer!  ;-)

-- 
..med vennlig hilsen = with Kind Regards from Arnt... ;-)
...with a number of polar bear hunters in his ancestry...
  Scenarios always come in sets of three: 
  best case, worst case, and just in case.




Re: ..idea; ddos spam hosts off Internet?

2004-04-09 Thread Russell Coker
On Fri, 9 Apr 2004 21:32, Arnt Karlsen <[EMAIL PROTECTED]> wrote:
> On Fri, 9 Apr 2004 15:27:03 +1000, Russell wrote in message
> > http://www.netfilter.org/patch-o-matic/pom-base.html
> >
> > See the section on "osf" in the above URL for a better solution.
> > Simply block Windows machines from accessing your port 25.
>
> ..if only all isp's did it...

Not all ISPs need to do it.  Only your ISP and the ISPs that host mailing 
lists that you subscribe to.

If you are interested in this then the best thing you can do is to build 
yourself a kernel with osf and try it out.  If it works well create a Debian 
kernel-patch package for it so that other Debian users can conveniently use 
it.  The more accessible you make this to Debian people the closer it comes 
to being installed on Debian list servers...

-- 
http://www.coker.com.au/selinux/   My NSA Security Enhanced Linux packages
http://www.coker.com.au/bonnie++/  Bonnie++ hard drive benchmark
http://www.coker.com.au/postal/Postal SMTP/POP benchmark
http://www.coker.com.au/~russell/  My home page


-- 
To UNSUBSCRIBE, email to [EMAIL PROTECTED]
with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]



Re: ..idea; ddos spam hosts off Internet?

2004-04-09 Thread Arnt Karlsen
On Fri, 9 Apr 2004 15:27:03 +1000, Russell wrote in message 
<[EMAIL PROTECTED]>:

> On Fri, 9 Apr 2004 09:51, Arnt Karlsen <[EMAIL PROTECTED]> wrote:
> > ..another idea; DDOS'ing spam hosts _off_ the net, say by using
> > other spam hosts as DOS relays?  Spam headers contain the
> > originating ip, and 2 such _can_ be set up to DOS each other. 
> > _Etc_.
> 
> The problem is that such attacks are a crime, and you are probably
> easier for the authorities to catch then the spammer...

..most places, agreed.

> > ..these spam hosts are commonly virus infected Wintendo's without
> > the owner knowing, as such unsuspecting owners feel their box
> > appears to work normally.
> >
> > ..these virus infected Wintendos should be taken off-line, anyway,
> > and made secure. And isp's should have a policy on such abuse,
> > and enforce it.
> 
> http://www.netfilter.org/patch-o-matic/pom-base.html
> 
> See the section on "osf" in the above URL for a better solution. 
> Simply block Windows machines from accessing your port 25.

..if only all isp's did it...

> > ..outside Internet, similar action is warranted in many
> > jurisdictions, by laws governing emergencies, for example, breaking
> > into your neighbors house to take his computer is a criminal
> > offence, but may be warranted if his house is ablaze and you know
> > the loss of his data will destroy his business.
> 
> I doubt that any court would rule that a DDOS attack is lawful,
> particularly as the attack would mostly harm an innocent ISP that has
> a Windows luser as a customer (all ISPs have lame customers).

..argueably, yes, however in the case of the lame isp's, 
there's possibly an opening for such court rulings. 

> > ..Bill Gates' proposal of email-for-a-fee-to-Microsoft to solve
> > this, is IMHO pure racism, as is Nigeria's 419 legislation, as it
> > effectively denies all other Africans and many Asians the access to
> > the free email that you and I enjoy.
> 
> I don't want to send email to Microsoft anyway...  ;)

.. ;-)  The Microsoft scheme is a M$ scheme, their idea is 
collect the M$ thru their "passport" "service", AFAIUI.

..and, booo, you cc'ed me, spammer!  ;-)

-- 
..med vennlig hilsen = with Kind Regards from Arnt... ;-)
...with a number of polar bear hunters in his ancestry...
  Scenarios always come in sets of three: 
  best case, worst case, and just in case.


-- 
To UNSUBSCRIBE, email to [EMAIL PROTECTED]
with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]



Re: ..idea; ddos spam hosts off Internet?, was: ...please

2004-04-09 Thread Russell Coker
On Fri, 9 Apr 2004 09:51, Arnt Karlsen <[EMAIL PROTECTED]> wrote:
> ..another idea; DDOS'ing spam hosts _off_ the net, say by using other
> spam hosts as DOS relays?  Spam headers contain the originating ip,
> and 2 such _can_ be set up to DOS each other.  _Etc_.

The problem is that such attacks are a crime, and you are probably easier for 
the authorities to catch then the spammer...

> ..these spam hosts are commonly virus infected Wintendo's without the
> owner knowing, as such unsuspecting owners feel their box appears to
> work normally.
>
> ..these virus infected Wintendos should be taken off-line, anyway,
> and made secure. And isp's should have a policy on such abuse,
> and enforce it.

http://www.netfilter.org/patch-o-matic/pom-base.html

See the section on "osf" in the above URL for a better solution.  Simply block 
Windows machines from accessing your port 25.

> ..outside Internet, similar action is warranted in many jurisdictions,
> by laws governing emergencies, for example, breaking into your neighbors
> house to take his computer is a criminal offence, but may be warranted
> if his house is ablaze and you know the loss of his data will destroy
> his business.

I doubt that any court would rule that a DDOS attack is lawful, particularly 
as the attack would mostly harm an innocent ISP that has a Windows luser as a 
customer (all ISPs have lame customers).

> ..Bill Gates' proposal of email-for-a-fee-to-Microsoft to solve this, is
> IMHO pure racism, as is Nigeria's 419 legislation, as it effectively
> denies all other Africans and many Asians the access to the free
> email that you and I enjoy.

I don't want to send email to Microsoft anyway...  ;)

-- 
http://www.coker.com.au/selinux/   My NSA Security Enhanced Linux packages
http://www.coker.com.au/bonnie++/  Bonnie++ hard drive benchmark
http://www.coker.com.au/postal/Postal SMTP/POP benchmark
http://www.coker.com.au/~russell/  My home page




Re: ..idea; ddos spam hosts off Internet?, was: ...please

2004-04-08 Thread Russell Coker
On Fri, 9 Apr 2004 09:51, Arnt Karlsen <[EMAIL PROTECTED]> wrote:
> ..another idea; DDOS'ing spam hosts _off_ the net, say by using other
> spam hosts as DOS relays?  Spam headers contain the originating ip,
> and 2 such _can_ be set up to DOS each other.  _Etc_.

The problem is that such attacks are a crime, and you are probably easier for 
the authorities to catch then the spammer...

> ..these spam hosts are commonly virus infected Wintendo's without the
> owner knowing, as such unsuspecting owners feel their box appears to
> work normally.
>
> ..these virus infected Wintendos should be taken off-line, anyway,
> and made secure. And isp's should have a policy on such abuse,
> and enforce it.

http://www.netfilter.org/patch-o-matic/pom-base.html

See the section on "osf" in the above URL for a better solution.  Simply block 
Windows machines from accessing your port 25.

> ..outside Internet, similar action is warranted in many jurisdictions,
> by laws governing emergencies, for example, breaking into your neighbors
> house to take his computer is a criminal offence, but may be warranted
> if his house is ablaze and you know the loss of his data will destroy
> his business.

I doubt that any court would rule that a DDOS attack is lawful, particularly 
as the attack would mostly harm an innocent ISP that has a Windows luser as a 
customer (all ISPs have lame customers).

> ..Bill Gates' proposal of email-for-a-fee-to-Microsoft to solve this, is
> IMHO pure racism, as is Nigeria's 419 legislation, as it effectively
> denies all other Africans and many Asians the access to the free
> email that you and I enjoy.

I don't want to send email to Microsoft anyway...  ;)

-- 
http://www.coker.com.au/selinux/   My NSA Security Enhanced Linux packages
http://www.coker.com.au/bonnie++/  Bonnie++ hard drive benchmark
http://www.coker.com.au/postal/Postal SMTP/POP benchmark
http://www.coker.com.au/~russell/  My home page


-- 
To UNSUBSCRIBE, email to [EMAIL PROTECTED]
with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]