I've just been setting up some pptp servers for mobile phone VPN use. Rumor had it that CyanogenMod would allow me to choose whether to route all traffic via the VPN, but I've installed the latest stable release and it appears to lack such functionality. Anyway one thing that's annoying is that I have to enter a password every time. That leads to a choice between a poor password that's easy to remember or a good password that needs to be written down, and both of those cases involve annoying typing. The VPN client will store the user-name though. So I was wondering whether the user-name is encrypted, if so I could use "1" for the password and have the random 8 character string as the user-name. I believe that the loss of email from a stolen phone is a much greater concern than the loss of a VPN password, among other things the VPN password can be trivially changed but the IMAP mail that is cached in the phone is lost to the attacker. http://en.wikipedia.org/wiki/Pptp#Security_of_the_PPTP_protocol Wikipedia says that the security of PPTP is weak. This isn't even including the case that any system which only has a user-name and password supplied by the client and no stored authentication token stored by either side (EG like the ~/.ssh/known_hosts) is going to lose in some way if the hostile party can proxy the protocol. In terms of setting up the server on Linux I just had to add something like the following to /etc/ppp/chap-secrets: USER pptpd PASS * Then I set suitable IP addresses in /etc/pptpd.conf . It wasn't difficult although mistakes with the chap-secrets file and attempts to get PAP working wasted a bit of time. -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/
Quoting Russell Coker (russell@coker.com.au):
Wikipedia says that the security of PPTP is weak.
{nostalgia} My, how times change. When I mentioned that _very_ fact a bit over a decade ago, on a mailing list thread[1] in July 2001, to help a user avoid using very bad security, that triggered off what eventually emerged as a long-term character-assassination campaign against yr. humble servant that one Russ P. Herrold and a small motley crew of fellow passive-aggressives started, carried out both behind my back[2] and to my face[3], and coordinating via a mailing list in rural Florida. Because, I assume, they all desperately needed hobbies. ;-> And, astoundingly, PPTP security is _still_ weak. [1] http://lists.svlug.org/archives/svlug/2001-July/033164.html http://lists.svlug.org/archives/svlug/2001-July/033228.html http://lists.svlug.org/archives/svlug/2001-July/033231.html [2] http://slugarchives.nks.net/List/slug-politics.archive.0107/0058.html [3] At the same time as the behind-my-back posting in Florida, Herrold tried to troll me via (unsolicited) personal mail, to which I attempted to respond constructively:
I wonder sometimes if you've studied under DJBernstein; I consider it part of your charm.
Dan threatens to throw people off his mailing lists if they talk about patches that he disapproves of. He calls them names; he threatens litigation. I do none of those things. I state my views on technology. Sometimes, someone does something like ask on a mailing list "How do I implement PPTP on Linux?" I feel free to reply "PPTP is a terrible security solution, and here's why." Because that's the best advice I feel I can give on the subject. When people then complain that I haven't answered the original question, and start calling me names, I have to start wondering who's out of line. I'm told that giving what I consider the best advice I can offer is "not helping the user", because it doesn't include the requested data. I consider that rubbish. I'm told that I'm somehow preventing others from speaking differently. That's rubbish, too. And I'm intrigued at the notion of this being similar to what Dan Bernstein does. Would you care to explain? No good deed, and all that.
Rick Moen <rick@linuxmafia.com> wrote:
My, how times change. When I mentioned that _very_ fact a bit over a decade ago, on a mailing list thread[1] in July 2001, to help a user avoid using very bad security, that triggered off what eventually emerged as a long-term character-assassination campaign against yr. humble servant that one Russ P. Herrold and a small motley crew of fellow passive-aggressives started, carried out both behind my back[2] and to my face[3], and coordinating via a mailing list in rural Florida. Because, I assume, they all desperately needed hobbies. ;->
Life's too short for personal attacks, coordinated or otherwise. Besides, they tend to escalate conflict and harm the reputation of the perpetrator.
And, astoundingly, PPTP security is _still_ weak.
I suspect that's one reason why technically informed contributors to this and other fora usually recommend OpenVPN or IPSec instead.
Quoting Jason White (jason@jasonjgw.net):
Life's too short for personal attacks, coordinated or otherwise. Besides, they tend to escalate conflict and harm the reputation of the perpetrator.
Wisdom.
I suspect that's one reason why technically informed contributors to this and other fora usually recommend OpenVPN or IPSec instead.
I was just going to mention that. OpenVPN has the virtue of being able to connect to a variety of server-end implementations, including Cisco's. Occasionally, people say they are obliged to use badly architected and implemented protocols like PPTP on account of mandate from management to use such things. I have somewhere details of what's available on Linux for that and some others, but would have to dig for it.
Rick Moen <rick@linuxmafia.com> wrote:
Occasionally, people say they are obliged to use badly architected and implemented protocols like PPTP on account of mandate from management to use such things. I have somewhere details of what's available on Linux for that and some others, but would have to dig for it.
Another legitimate reason would be a need to access an employer's or collaborator's network that just happens to use pptp (unwise as it is to do so).
Quoting Jason White (jason@jasonjgw.net):
Another legitimate reason would be a need to access an employer's or collaborator's network that just happens to use pptp (unwise as it is to do so).
That would actually be exactly the sort of 'mandate from management to use such things' I had in mind.
On 08/12/2011, at 20:11, Rick Moen <rick@linuxmafia.com> wrote:
I suspect that's one reason why technically informed contributors to this and other fora usually recommend OpenVPN or IPSec instead.
I was just going to mention that. OpenVPN has the virtue of being able to connect to a variety of server-end implementations, including Cisco's.
openvpn to Cisco? really? I've never come across this, but it would be invaluable
I was just going to mention that. OpenVPN has the virtue of being
able to
connect to a variety of server-end implementations, including Cisco's.
Do you have a reference for this? None of the literature I've read on the subject make any claims for this sort of interoperability. For this to be the case either OpenVPN would need to talk IPSEC to Cisco endpoints, or Cisco endpoints would need to understand OpenVPN. You didn't mean openswan or freeswan did you? I seem to remember that they can be configured to talk to Cisco endpoints... James
Quoting James Harper (james.harper@bendigoit.com.au):
Do you have a reference for this? None of the literature I've read on the subject make any claims for this sort of interoperability.
I'm probably misremembering, then. It was one of the currently available and open source implementations for Linux. I'd have to do some checking to find that answer. (Me, I'm in a position to be able to mostly just rely on SSH, which meets my needs. I don't need to tunnel SMB and such.)
Quoting James Harper (james.harper@bendigoit.com.au):
Do you have a reference for this? None of the literature I've read on the subject make any claims for this sort of interoperability.
I'm probably misremembering, then. It was one of the currently available and open source implementations for Linux. I'd have to do some checking to find that answer.
I suspect you're thinking of OpenSwan/FreeSwan then.
(Me, I'm in a position to be able to mostly just rely on SSH, which meets my needs. I don't need to tunnel SMB and such.)
SMB over a WAN is pretty painful anyway. SMB2 is allegedly better but I haven't had the opportunity to compare. James
On 08/12/11 20:11, Rick Moen wrote:
I was just going to mention that. OpenVPN has the virtue of being able to connect to a variety of server-end implementations, including Cisco's.
This is false, unless proven otherwise. OpenVPN is a non-standard VPN protocol not supported by Cisco. Not that Cisco is above using non-standard protocols themselves. ;-)
Quoting Jeremy Visser (jeremy@visser.name):
This is false, unless proven otherwise.
You know, I really had no idea that several people were going to glom like shark-hungry ramoras onto a half-remembered guess regarding an entirely tangential subject that I threw casually into a thread where I was _actually_ attempting to make the point that various open-source client packages are often able to connect to even badly designed and implemented crypto gateways mandated by inept and hapless managers. The first name that leapt to mind happened to be OpenVPN, rather than OpenSWAN, strongSWAN, n2n, (formerly) FreeS/WAN, just the Linux IPsec stack by itself, or what-all. But the point was that what's available in that department often suffices. (The point was not which one of those I happened to mention.) I personally have been lucky enough to, in general, just use standard Unix tools and ssh tunnels, as I also mentioned. Sucks to be you guys and have to do L2TP over IPSEC and similar demented things, so you _do_ have my sympathies.
OpenVPN is a non-standard VPN protocol not supported by Cisco.
Since you're being unbelievably picky: No, OpenVPN is not a protocol at all, regardless of whether standard or not.
Rick Moen <rick@linuxmafia.com> wrote:
I personally have been lucky enough to, in general, just use standard Unix tools and ssh tunnels, as I also mentioned. Sucks to be you guys and have to do L2TP over IPSEC and similar demented things, so you _do_ have my sympathies.
I concur. I've tried plain IPSec over IPv6 (mostly for experimental purposes), and I occasionally run vpnc to access a VPN, but, in general, I'm lucky enough to be in Rick's position. One application of IPSec that I'm quite interested in is mobile IPv6. If my laptop could maintain the same address when it isn't at home, without the packets having to detour via my ADSL line, that would be nice to have.
Quoting Jeremy Visser (jeremy@visser.name):
This is false, unless proven otherwise.
You know, I really had no idea that several people were going to glom
like
shark-hungry ramoras onto a half-remembered guess regarding an entirely tangential subject that I threw casually into a thread where I was _actually_ attempting to make the point that various open-source client packages are often able to connect to even badly designed and implemented crypto gateways mandated by inept and hapless managers. The first name that leapt to mind happened to be OpenVPN, rather than OpenSWAN, strongSWAN, n2n, (formerly) FreeS/WAN, just the Linux IPsec stack by itself, or what-all. But the point was that what's available in that department often suffices. (The point was not which one of those I happened to mention.)
I know it sucks to be wrong, but it sucks even more to be googling and come across wrong information on a mailing list archive with no follow up posts to correct it. I've heard a few people say before that "OpenVPN and Cisco work well together" and such misinformation helps nobody. James
Quoting James Harper (james.harper@bendigoit.com.au):
I know it sucks to be wrong, but it sucks even more to be googling and come across wrong information on a mailing list archive with no follow up posts to correct it.
1. I really don't care about being wrong. Have a lot of experience at it. Twice on Sundays. 2. Your assumption that was 'googling' is incorrect. I just made an off-the-cuff (and, as mentioned, tangential) comment just before going to sleep. 3. There were 'no follow up posts' largely because I was immediately thereafter asleep. (See 'just before going to sleep'.) Not counting the one I wrote fairly soon thereafter where I said, gee, sorry, I obviously must have misremembered, then. Probably one of the other ones in the category of which I spoke.
...such misinformation helps nobody
OH NOEZ! SOMEBODY WAS WRONG ON THE INTERNETZ! Hurry, somebody tell Randall Munroe. https://www.xkcd.com/386/ [1] [1] My wife has licence plate 'XKCD386'. It has many admirers.
On 08/12/2011, at 8:02 PM, Jason White wrote:
And, astoundingly, PPTP security is _still_ weak.
I suspect that's one reason why technically informed contributors to this and other fora usually recommend OpenVPN or IPSec instead.
Jason (and any other VPN protocol experts on the list), I'm curious: how well supported is OpenVPN and/or IPSec across other platforms? I support a PPTP-based VPN system where the reduced security was deemed (almost) acceptable given that it works with a wide range of operating systems, including various flavours of Linux, Android, iOS and Mac OS X, that our users are using. The last time I looked, PPTP was the only VPN solution that had good cross-platform support on all those platforms. For example, I don't know of an OpenVPN client for (non-jail-broken) iOS clients. I'm really keen to know if that has changed, as I would love to offer a more secure solution. Ideally it would not be too much harder to set up than PPTP either, as many times the users are setting up their VPN connection remotely. Regards Graeme
On Thu, 8 Dec 2011, Graeme Cross <gcross@fastmail.fm> wrote:
The last time I looked, PPTP was the only VPN solution that had good cross-platform support on all those platforms. For example, I don't know of an OpenVPN client for (non-jail-broken) iOS clients.
This is exactly the problem that I have. My client uses an iPhone because he does everything with Apple and because there are some specific iPhone programs he needs to use. So the question is, what is the best that I can do with an iPhone as the primary client device? -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/
On Thu, 8 Dec 2011, Graeme Cross <gcross@fastmail.fm> wrote:
The last time I looked, PPTP was the only VPN solution that had good cross-platform support on all those platforms. For example, I don't know of an OpenVPN client for (non-jail-broken) iOS clients.
This is exactly the problem that I have. My client uses an iPhone
because he
does everything with Apple and because there are some specific iPhone programs he needs to use.
So the question is, what is the best that I can do with an iPhone as the primary client device?
Looking at my iPhone, my VPN options are L2TP, PPTP, and IPSec. The IPSec appears to be Cisco flavoured but last time I checked I think the Linux IPSEC implementation claimed compatibility with Cisco IPSEC... that was a long time ago though so I may be wrong. My iPhone also claimed support for RSA SecurID, or a password that can be saved or "ask every time". If you can get IPSEC working with the iPhone that will be the best option I think. Googling for Openswan and iphone looks superficially promising, but you may find it less promising if you dig further. http://www.jacco2.dds.nl/networking/freeswan-panther.html#iPhone says: The iPhone is based on Mac OS X. It ships with a built-in client that supports a number of VPN protocols including L2TP/IPsec. I have no first hand experience with the iPhone. Kim Hendrikse reports that the iPhone connects to an Openswan based L2TP/IPsec server but for some reason the iPhone disconnects within a minute if there is no payload traffic, no matter if you use PPP/L2TP/IPsec's keep alive mechanisms. According to an Astaro press release, their Astaro Security Gateway appliance is compatible with the iPhone for both L2TP/IPsec and PPTP. The Astaro Security Gateway is based on Linux (Strongswan, l2tpd etc.) so I suppose it also works with the setup described on this webpage. Most of the links I checked are just as non-committed. I'm not sure if the L2TP option is L2TP + IPSEC either... I have no use for a VPN on my iPhone as I can access all my services externally via HTTPS or SSH. Good luck! James
On 08/12/2011, at 22:06, "James Harper" <james.harper@bendigoit.com.au> wrote:
On Thu, 8 Dec 2011, Graeme Cross <gcross@fastmail.fm> wrote:
The last time I looked, PPTP was the only VPN solution that had good cross-platform support on all those platforms. For example, I don't know of an OpenVPN client for (non-jail-broken) iOS clients.
This is exactly the problem that I have. My client uses an iPhone because he does everything with Apple and because there are some specific iPhone programs he needs to use.
So the question is, what is the best that I can do with an iPhone as the primary client device?
I'd say l2tp/IPSec is the better choice.
Looking at my iPhone, my VPN options are L2TP, PPTP, and IPSec. The IPSec appears to be Cisco flavoured but last time I checked I think the Linux IPSEC implementation claimed compatibility with Cisco IPSEC...
often the Cisco IPSec means it does gre over IPSec, for mobile users.
If you can get IPSEC working with the iPhone that will be the best option I think. Googling for Openswan and iphone looks superficially promising, but you may find it less promising if you dig further. http://www.jacco2.dds.nl/networking/freeswan-panther.html#iPhone says:
they are referencing very old versions of iOS. at least in my iOS 5 devices, multiple of each type of VPN can be configured, and also supports RSA SecureID tokens. the Cisco VPN is still the only one to support certificate based auth, though. I've only used the iOS VPN to connect to OSX servers, but it has so far been reliable and simple. I'm sure a lot of the other bugs have been worked out since iOS 1.0 in the article, as more and more people are wanting to connect to non-Apple implementations of IPSec.
hannah commodore <hannah@tinfoilhat.net> wrote:
I'd say l2tp/IPSec is the better choice.
You could try it with strongswan, which, as I recall, supports it. If you need IKEv1 aggressive mode, then Openswan is the best choice. Strongswan developers decided not to support IKEv1 aggressive mode, for security reasons: http://wiki.strongswan.org/projects/strongswan/wiki/FAQ If your client device supports IKEv2, then it seems that would be the best solution (with either Strongswan or Openswan - the former supports more protocols). Big disclaimer: I'm not well informed about IPSec; experts on the list are welcome to correct the above comments.
On Thu, 8 Dec 2011, "James Harper" <james.harper@bendigoit.com.au> wrote:
Looking at my iPhone, my VPN options are L2TP, PPTP, and IPSec. The IPSec appears to be Cisco flavoured but last time I checked I think the Linux IPSEC implementation claimed compatibility with Cisco IPSEC... that was a long time ago though so I may be wrong. My iPhone also claimed support for RSA SecurID, or a password that can be saved or "ask every time".
My impression is that RSA SecurID is just a different way of supplying a password to be used by one of the other sessions. Admittedly if a session had password discovery as the most concerning weakness (which may be the case here) then that would solve things nicely. But other than that it doesn't seem to be a great benefit.
If you can get IPSEC working with the iPhone that will be the best option I think. Googling for Openswan and iphone looks superficially promising, but you may find it less promising if you dig further. http://www.jacco2.dds.nl/networking/freeswan-panther.html#iPhone says:
The ADSL device has no apparent support for forwarding IPSEC. It does PPTP, http, https, and a bunch of gaming protocols. So basically anything that runs over TCP on arbitrary ports can be made to work (presumably they wouldn't attempt to mess with the HTTPS protocol and wouldn't bother much with some of the other protocols like HTTP). But it doesn't seem that the iPhone does that.
I'm not sure if the L2TP option is L2TP + IPSEC either... I have no use for a VPN on my iPhone as I can access all my services externally via HTTPS or SSH.
The company that supplies some of the server software I am dealing with expressed their level of confidence in their work by recommending that it be protected by a VPN. :( -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/
Looking at my iPhone, my VPN options are L2TP, PPTP, and IPSec. The IPSec appears to be Cisco flavoured but last time I checked I think the Linux IPSEC implementation claimed compatibility with Cisco IPSEC... that was a long time ago though so I may be wrong. My iPhone also claimed support for RSA SecurID, or a password that can be saved or "ask every time".
My impression is that RSA SecurID is just a different way of supplying a password to be used by one of the other sessions. Admittedly if a session had password discovery as the most concerning weakness (which may be the case here) then that would solve things nicely. But other than that it doesn't seem to be a great benefit.
Yes... after posting that I figured it wasn't what you were asking for...
If you can get IPSEC working with the iPhone that will be the best option I think. Googling for Openswan and iphone looks superficially promising, but you may find it less promising if you dig further. http://www.jacco2.dds.nl/networking/freeswan-panther.html#iPhone says:
The ADSL device has no apparent support for forwarding IPSEC. It does PPTP, http, https, and a bunch of gaming protocols. So basically anything that runs over TCP on arbitrary ports can be made to work (presumably they wouldn't attempt to mess with the HTTPS protocol and wouldn't bother much with some of the other protocols like HTTP). But it doesn't seem that the iPhone does that.
IPSEC can NAT over a pair of UDP ports... which isn't to say that the iPhone actually supports that. It would definitely be a trek into the unknown that may not lead anywhere.
I'm not sure if the L2TP option is L2TP + IPSEC either... I have no use for a VPN on my iPhone as I can access all my services externally via HTTPS or SSH.
The company that supplies some of the server software I am dealing with expressed their level of confidence in their work by recommending that it be protected by a VPN. :(
Ah. A vendor that doesn't have any understanding of the world outside their ivory tower :) James
The VPN client will store the user-name though. So I was wondering whether the user-name is encrypted, if so I could use "1" for the password and have the random 8 character string as the user-name. I believe that the loss of email from a stolen phone is a much greater concern than the loss of a VPN password, among other things the VPN password can be trivially changed but the IMAP mail that is cached in the phone is lost to the attacker.
http://en.wikipedia.org/wiki/Pptp#Security_of_the_PPTP_protocol
Wikipedia says that the security of PPTP is weak. This isn't even including the case that any system which only has a user-name and password supplied by the client and no stored authentication token stored by either side (EG like the ~/.ssh/known_hosts) is going to lose in some way if the hostile party can proxy the protocol.
Well PPTP is more or less just a wrapper around PPP, so it's roughly as secure as that but the features supported depend on the implementation. As you imply, if you don't use peer authentication in some form or another (eg PAP on the client or certificate exchange), how can you be sure that you are connecting to your network and not my man-in-the-middle network? What services are you running behind the VPN? If they are all SSL or TLS based and you are just using the VPN to do routing and not security then you are probably okay as long as the correct identification is done there. It's surprising how often PPTP is still used these days. Windows has supported IPSEC+L2TP for (nearly?) a decade which provides a highly secure link, and all the NAT hurdles were solved for at least the last 5 years, but people still insist on using PPTP, even though that's almost as tricky to NAT. James James
participants (7)
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Graeme Cross -
hannah commodore -
James Harper -
Jason White -
Jeremy Visser -
Rick Moen -
Russell Coker