RE: (OT)Ham Radio + SMTP (was Re: How to restrict encrypted email)

2016-07-18 Thread Michael Fox
> My understanding is that packet radio has been allowed in part of the > HAM band and in part of the Marine SSB band for quite a long time. > > Curtis That's correct Curtis. In fact, worldwide electronic mail was possible with packet and the worldwide BBS network long before commercial Interne

Re: (OT)Ham Radio + SMTP (was Re: How to restrict encrypted email)

2016-07-18 Thread Curtis Villamizar
In message <20160716192156.09767350@kendramatic> jdebert writes: > > On Sat, 16 Jul 2016 11:42:44 -0400 > Yuval Levy wrote: > > > It is indeed a matter of interpretation, and I would like to see the > > FCC rules text. Questions: > > (1) how do they define "encrypted"? > > The rules and regu

Re: SV: How to restrict encrypted email

2016-07-17 Thread Albrecht Dreß
Am 16.07.16 21:30 schrieb(en) Sebastian Nielsen: You could use iptables to look for: "--BEGIN" "--END" "/signed" "/encrypted" "/pkcs7" "/pgp" Anywhere in the packet. In that case, you drop the connection, send a RST IMO this is too restrictive as it would produce false positives, e.g. for you

(OT)Ham Radio + SMTP (was Re: How to restrict encrypted email)

2016-07-16 Thread jdebert
On Sat, 16 Jul 2016 11:42:44 -0400 Yuval Levy wrote: > It is indeed a matter of interpretation, and I would like to see the > FCC rules text. Questions: > (1) how do they define "encrypted"? The rules and regulations are very clear on what is permitted. They do not need to define anything else.

RE: How to restrict encrypted email

2016-07-16 Thread Michael Fox
> You could use iptables to look for: > "--BEGIN" > "--END" > "/signed" > "/encrypted" > "/pkcs7" > "/pgp" Thanks to all. I've got enough to get me started with my homework. Lots to learn. Regards, Michael

SV: How to restrict encrypted email

2016-07-16 Thread Sebastian Nielsen
The problem you got, is that the encrypted content has already travelled the amateur frequencies even if you block/reject the mail. Thus the rules are already broken, thus you should deal with those users in a "AUP" way even if the mail gets blocked. Better might be to block this in firewall then.

Re: How to restrict encrypted email

2016-07-16 Thread Larry Stone
> On Jul 16, 2016, at 11:11, Erwan David wrote: > >> Le 16/07/2016 à 19:04, Jan Ceuleers a écrit : >>> On 16/07/16 17:42, Yuval Levy wrote: >>> Imposing the onus on the SMTP server operator is like imposing the onus >>> on gas stations for fueling vehicles used in criminal endeavors. It >>> doe

RE: How to restrict encrypted email

2016-07-16 Thread Michael Fox
Michael Fox: > > So, are there other obvious ways to recognize encrypted contents, other > than > > "Content-Type: multipart/encrypted"? Albrecht: > Basically, you need to check for > - OpenPGP/Inline (inspect every body, see rfc 2440, sect. 6.2) > - OpenPGP/Mime (multipart/encrypted, see rfc 3156

Re: How to restrict encrypted email

2016-07-16 Thread Erwan David
Le 16/07/2016 à 19:04, Jan Ceuleers a écrit : > On 16/07/16 17:42, Yuval Levy wrote: >> Imposing the onus on the SMTP server operator is like imposing the onus >> on gas stations for fueling vehicles used in criminal endeavors. It >> does not fly because the gas station can't possibly know what th

Re: How to restrict encrypted email

2016-07-16 Thread Jan Ceuleers
On 16/07/16 17:42, Yuval Levy wrote: > Imposing the onus on the SMTP server operator is like imposing the onus > on gas stations for fueling vehicles used in criminal endeavors. It > does not fly because the gas station can't possibly know what the user > will use the vehicle for, other than (prob

Re: How to restrict encrypted email

2016-07-16 Thread Yuval Levy
(Non-US) lawyer here, chiming in after the itch became to strong. Initially I wanted to stay out of this debate, the solution of which is obviously non-technical and probably OT. DISCLAIMER: THE FOLLOWING IS NOT LEGAL ADVICE. On 16-07-16 11:04 AM, /dev/rob0 wrote: > You have already discarded STA

Re: How to restrict encrypted email

2016-07-16 Thread Erwan David
Le 16/07/2016 à 16:49, Jan Ceuleers a écrit : > On 16/07/16 15:59, Michael Fox wrote: >> So, are there other obvious ways to recognize encrypted contents, other than >> "Content-Type: multipart/encrypted"? > Theoretical (and therefore possibly entirely impractical) answer: > > Encrypted data contai

Re: How to restrict encrypted email

2016-07-16 Thread /dev/rob0
On Fri, Jul 15, 2016 at 10:25:43PM -0700, Michael Fox wrote: > I'd like to be able to reject mail that contains encrypted content. > This is to satisfy US FCC rules against encrypted content on > amateur radio frequencies. Some of our clients may connect via > amateur radio. I think you're ta

Re: How to restrict encrypted email

2016-07-16 Thread Jan Ceuleers
On 16/07/16 15:59, Michael Fox wrote: > So, are there other obvious ways to recognize encrypted contents, other than > "Content-Type: multipart/encrypted"? Theoretical (and therefore possibly entirely impractical) answer: Encrypted data contains a high amount of entropy, meaning that it does not

Re: How to restrict encrypted email

2016-07-16 Thread Erwan David
Le 16/07/2016 à 16:39, Phil Stracchino a écrit : > On 07/16/16 10:32, Albrecht Dreß wrote: >> Am 16.07.16 15:59 schrieb(en) Michael Fox: >>> So, are there other obvious ways to recognize encrypted contents, other than >>> "Content-Type: multipart/encrypted"? >> Basically, you need to check for >> -

Re: How to restrict encrypted email

2016-07-16 Thread Phil Stracchino
On 07/16/16 10:32, Albrecht Dreß wrote: > Am 16.07.16 15:59 schrieb(en) Michael Fox: >> So, are there other obvious ways to recognize encrypted contents, other than >> "Content-Type: multipart/encrypted"? > > Basically, you need to check for > - OpenPGP/Inline (inspect every body, see rfc 2440, se

Re: How to restrict encrypted email

2016-07-16 Thread Albrecht Dreß
Am 16.07.16 15:59 schrieb(en) Michael Fox: So, are there other obvious ways to recognize encrypted contents, other than "Content-Type: multipart/encrypted"? Basically, you need to check for - OpenPGP/Inline (inspect every body, see rfc 2440, sect. 6.2) - OpenPGP/Mime (multipart/encrypted, see r

RE: How to restrict encrypted email

2016-07-16 Thread Michael Fox
> minimize it with some filtering for the obvious cases > as you propose. Thanks Marco. I hadn't thought of some of those cases. But I would still like to block the obvious cases, as you say. So, are there other obvious ways to recognize encrypted contents, other than "Content-Type: multipart/

Re: How to restrict encrypted email

2016-07-16 Thread Marco
Hello Michael. It is a near impossible task, as i.e. encrypted data can easily be transferred as uuencode text in a plain text message, and you will not notice this in the headers. And also trying to actively detected whether or not the body or the attachments of a message are encrypted is quite t

How to restrict encrypted email

2016-07-15 Thread Michael Fox
I'd like to be able to reject mail that contains encrypted content. This is to satisfy US FCC rules against encrypted content on amateur radio frequencies. Some of our clients may connect via amateur radio. I'd like to be able to restrict it only for certain clients. But, as I understand it, he