Here's the summary of yesterday's IRC meeting.



Place: #openvpn-meeting on irc.freenode.net
Date: Monday 10th October 2016
Time: 20:00 CEST (18:00 UTC)

Planned meeting topics for this meeting were here:


The next meeting has not been scheduled yet.

Your local meeting time is easy to check from services such as



cron2, danhunsaker, jamesyonan, lev, mattock, plaisthos, snair and syzzer participated in this meeting.


Discussed testing procedures for the "Windows: do_ifconfig() after open_tun()" patch version 2. While the patch passed cron2's test scripts, it was agreed that we should give people a chance to test the patch in their environments before releasing 2.4-alpha1.

Installers that contain the patch are already available here:


Things/use-cases that should be tested in particular are:

- Running without OpenVPN-GUI
- Running without the Interactive Service
- Running --server (on Windows)
- Using more than one tap adapter
- General openvpnserv2 testing

Mattock will make announcements about these installers (and subsequent installers) to the mailing lists as well as forums.


Discussed the "hide the scary message during Windows install" issue. The message is caused by

"sc.exe start OpenVPNServiceInteractive"

and it looks a lot like an error/warning, even though it is benign.

Mattock will try to make sc.exe less verbose.


Discussed management of IV_* (capability) values that clients send to the server. It was agreed that binding an IV_PROTO=<x> level to a set of more fine-grained IV_<capability> advertisements makes sense. While the space available for IV_* values is limited, OpenVPN 3 has worked around this without changing the protocol:


The same approach makes sense for OpenVPN 2.4 also. Adding receive (server) support would be safe to implement, but adding send (client) support needs to be done carefully so as not to break anything. This capability was not seen as a "must have" for OpenVPN 2.4-alpha1.


Discussed OpenVPN-GUI fixes from snair that should be included in 2.4-alpha1:


Mattock will have a look tomorrow and produce new installers as necessary.


Discussed OpenVPN 2.3.13 release. Three things are missing:

1. recursive routing
2. block-outside-dns v2
3. 64MB renegotiation for 64-bit block ciphers

Cron2 will take care of 1-2, and syzzer will tackle 3.


Preliminary release date for OpenVPN 2.4-alpha1 was set to late this week. If we don't get Windows test reports then we may have to postpone the release a bit. OpenVPN 2.3.13 release date was set to "early next week".


Full chatlog has been attached to this email.

Samuli Seppänen
Community Manager
OpenVPN Technologies, Inc

irc freenode net: mattock

(21:00:23) L'argomento per #openvpn-meeting è stato impostato da 
valdikss!~valdikss@2a02:7aa0:1619::2c32:9c23 a 21:38:35 su 22/08/2016
(21:00:39) lev__: sorry for that :(
(21:00:41) mattock: howdy
(21:01:07) syzzer: lev__: sorry?  no need, this is needed refactoring.
(21:01:34) ***lev__ was trying to make a joke
(21:01:39) cron2: more lkke "thanks for taking this" :)
(21:02:33) syzzer: ok, good ;)
(21:02:51) mattock: so meeting time now
(21:02:57) mattock: https://community.openvpn.net/openvpn/wiki/Topics-2016-10-10
(21:02:58) vpnHelper: Title: Topics-2016-10-10 – OpenVPN Community (at 
(21:03:13) mattock: request in #1 was fulled hours ago
(21:03:25) mattock: fulfilled :)
(21:03:29) ***cron2 likes to borrow that time machine
(21:04:59) ibins [~ib...@55d4345d.access.ecotel.net] è entrato nella stanza.
(21:05:50) mattock: sent mail about it 5 hours ago, but the links are on the 
(21:06:25) cron2: I've seen the mail (and I think I already said thanks) :-)
(21:06:47) mattock: ok
(21:06:55) mattock: did you have time to run the tests?
(21:07:09) cron2: so - if this isn't breaking people's windows setups, we can 
merge it, and have all "MUST HAVE!" bits for 2.4_alpha1
(21:07:45) cron2: there's more stuff out there that should go into 2.4 (TCP_NL, 
recursive routing, push option cleanup, ...) but this is more easily testable
(21:09:30) cron2: mattock: looking at plaisthos' TCP_NL patch - do you have an 
OpenVPN 3 test server available that we can test this against?
(21:09:41) mattock: no, I don't have one, but james might
(21:10:08) danhunsaker: James has ALL THE v3 SERVERS.
(21:10:18) cron2: *g*
(21:11:02) mattock: regarding windows testing: perhaps we should announce the 
installers I created so that (in theory) somebody would test it before 
2.4-alpha1 release
(21:11:11) mattock: give people a few days to test their setup wiht it
(21:11:25) cron2: +1
(21:11:35) mattock: ok, that I can do
(21:11:43) mattock: I'll send an announcement to forums also
(21:12:06) syzzer: yes, good plan
(21:12:28) plaisthos: cron2: I tested it against james server  if that helps
(21:13:12) cron2: plaisthos: well, it does, but I had hoped to test myself :)
(21:16:34) mattock: regarding the installer - I have another installer ready 
for testing that gets rid of the scary (sc.exe) message at the end of the 
(21:16:34) snair [~snair@2600:3c03:e001:3b00::1004] è entrato nella stanza.
(21:16:48) mattock: scary as in "did it fail?"
(21:17:27) mattock: I just have yet had time to verify if the fix works
(21:17:40) mattock: will do that tomorrow
(21:20:46) mattock: anything else for 2.4-alpha1?
(21:21:38) cron2: all my urgent topics are covered :)
(21:22:12) cron2: (windows testing could be improved, but having the basic 
run/run2.bat scripts helped me quite a bit)
(21:22:34) mattock: ok, great!
(21:23:08) mattock: so I'll announce a pre-alpha1 installer tomorrow
(21:23:22) mattock: we could probably publish 2.4-alpha1 by the end of the week 
(21:24:14) mattock: so move on to 2.3.13?
(21:24:30) cron2: syzzer, lev__: any comments on 2.4_alpha1?  plaisthos?
(21:25:05) plaisthos: I would like my two patches in it 
(21:25:06) syzzer: nope, would be good to get it out asap
(21:25:12) plaisthos: but otherwisee, get going
(21:25:23) cron2: plaisthos: vpn-helper is slow today
(21:25:42) plaisthos: are we upping IV_PROTO?
(21:25:52) plaisthos: or do we keep IV_GW_IPV6 and co?
(21:25:56) cron2: have we agreed on anything?  this is a good point indeed
(21:26:24) lev__: well, recursive routing would be nice to have - we got quite 
a few compains from customers about that (until it was fixed, well almost)
(21:26:46) cron2: lev__: not forgotten, but doesn't *need* to be in alpha1 
(needs to be in 2.4-release)
(21:26:55) plaisthos: steffan wanted some hash negoiation and then do that in 
one go
(21:27:08) cron2: syzzer: *poke*
(21:27:41) syzzer: yes, I need to do that
(21:28:17) syzzer: I think increasing IV_PROTO makes sense
(21:28:51) cron2: but this needs to be coordinated with james, so the 2.4 and 3 
can properly interop...
(21:28:59) syzzer: indeed
(21:29:56) snair: What about topology -- recall a mention that subnet will be 
the default in 2.4
(21:30:59) danhunsaker: Oh, hey, just remembered that AS is already using 3...  
So I actually do have a v3 test server or three.
(21:31:05) mattock: maybe I'll email james?
(21:31:10) cron2: danhunsaker: regular AS?
(21:31:17) danhunsaker: Yeah.
(21:31:19) cron2: cool
(21:31:45) cron2: is the bundle to-be-installed on ubuntu also using 3 code?
(21:31:45) plaisthos: cron2: if you announche TCP_NL without actually 
supporting it it should brea pretty quickly
(21:32:04) plaisthos: snair: difficult
(21:32:11) danhunsaker: Should be.  As I understand it, AS has been using 3 for 
a while.
(21:32:12) plaisthos: would break existing configs
(21:32:25) cron2: plaisthos: will that depend on the number of cores and 
traffic on the 3 server side?  Or will it always produce async packets?
(21:32:54) plaisthos: cron2: with james ec2 cloud server it broke after 2-3s 
after starting wget
(21:33:31) cron2: ok, so this will be easy to test... just need to upgrade my 
ancient AS, then
(21:34:20) cron2: mmmh
(21:34:34) cron2: danhunsaker: I'm not sure I agree... looking at one of our 
customer servers, I get
(21:34:39) cron2: [root@vpn ~]# /usr/local/openvpn_as/sbin/openvpn-polarssl 
(21:34:39) cron2: OpenVPN 2.3_AS11c x86_64-unknown-linux-gnu [SSL (PolarSSL)] 
[LZO] [SNAPPY] [LZ4] [EPOLL] [MH] [IPv6] built on Jun 29 2016
(21:34:49) cron2: this looks definitely 2.x-ish
(21:35:03) mattock: I have not heard of AS using OpenVPN 3.x, and James did not 
mention anything along those lines in the Helsinki hackathon
(21:35:05) danhunsaker: Hrm.  I might be misled.  Lemme investigate further.
(21:35:11) cron2: thanks :)
(21:35:19) plaisthos: https://www.privatetunnel.com/home/ might be openvpn3
(21:35:53) mattock: that one is
(21:36:12) mattock: anyhow, I sent email to james - let's see if he could pop 
in for a minute
(21:36:26) mattock: he has been sending emails within a few minutes
(21:37:18) jamesyonan [~jamesy...@c-73-243-160-156.hsd1.co.comcast.net] è 
entrato nella stanza.
(21:37:27) plaisthos: Whee James! :)
(21:37:32) mattock: hi james!
(21:37:50) jamesyonan: Hi guys
(21:37:51) mattock: (21:28:17) syzzer: I think increasing IV_PROTO makes sense
(21:37:51) mattock: (21:28:51) cron2: but this needs to be coordinated with 
james, so the 2.4 and 3 can properly interop...
(21:39:04) syzzer: this is about plaisthos' proposal to 'squash' several of the 
IV_* values into IV_PROTO=3
(21:40:29) plaisthos: basically the idea is no longer announce IV_COMP_SUBv2, 
IV_TCP_NL and IV_RGI6 and if syzzer finishes soon enough also pushable --auth 
(21:40:56) plaisthos: and iirc also pushable/negoiable key derviation (no 
longer use md5 there)
(21:42:46) jamesyonan: I would tend to agree from experience that squashing 
protocol features into a bundle is simpler from an implementation and 
compatibility standpoint than trying to be fine-grained about everything.
(21:44:44) danhunsaker: cron2: Seems I was confusing PrivateTunnel and AS in my 
head while reading internal emails.  Sorry about that.  AS is, indeed, not on 
v3 yet.
(21:45:12) jamesyonan: for example in our OpenVPN-3 based server, we really 
only have two protocol modes, (a) legacy CBC/HMAC mode, and (b) AEAD/GCM mode 
with IV_NCP >= 2, IV_PROTO >= 2, and IV_COMP_STUBv2 >= 1.
(21:45:51) plaisthos: we can probably not include IV_NCP into IV_PROTO 3
(21:46:00) plaisthos: as openssl might be buld without aead
(21:46:24) cron2: or NCP might be turned off...
(21:49:22) jamesyonan: How about an approach where we stay fine-grained in the 
IV_x capability markers, but reserve the right at the implementation level to 
be coarse about which IV_x capabiities are required in order to elevate to the 
higher implementation level.
(21:49:52) jamesyonan: We are sort of doing that with OpenVPN 3 server in that 
we expect those three IV_x capabilties to line up before we upgrade to GCM.
(21:51:07) plaisthos: yeah, idea what more to include everything that is pretty 
much alwys there in IV_PROTO 3
(21:51:26) plaisthos: e.g. IV_PROTO 3 mean that the other features are also 
(21:52:20) plaisthos: to keep the IV list a bit smaller and cleaner
(21:52:38) plaisthos: 2.3 announced almost othing 
(21:52:59) plaisthos: and 2.4 has 13 things it announces
(21:53:36) plaisthos: and tcpnl and stubv2 and peer id is not going away I think
(21:55:51) syzzer: indeed, I think those should be implied by IV_PROTO=3
(21:56:04) syzzer: as would a possible switch of the PRF to SHA2
(21:57:02) cron2: that is an interesting one - the server would need to push 
that, *if* IV_PROTO=3 *and* the server can do it
(21:59:28) plaisthos: yeah, so?
(21:59:48) jamesyonan: If we are going to wrap these capabilties down to a 
scalar value, then keep in mind that OpenVPN 3 might accrue new protocol 
features on a different timeline than OpenVPN 2
(21:59:52) cron2: just pointing out that the PRF change cannot be done 
(22:00:16) plaisthos: jamesyonan: no ssingle sclar value
(22:00:36) jamesyonan: Like as I mentioned about, OpenVPN 3 has essentially 
defined a protocol level that is met when IV_NCP >= 2, IV_PROTO >= 2, and 
IV_COMP_STUBv2 >= 1.
(22:00:36) cron2: jamesyonan: right.  So we'll always have some sort of 
IV_PROTO=<x> which is synced, and then IV_ that add to it - and every so often, 
we can re-sync
(22:00:38) plaisthos: IV_PROTO=3 + IVs that are not included in IV_PROTO=3
(22:04:01) jamesyonan: so you're saying that we sync IV_ values from time to 
time into a new IV_PROTO level, only when OpenVPN 2 and 3 can both support the 
(22:04:35) danhunsaker: (I'm not sure it could be properly called a 'sync' 
(22:10:33) jamesyonan: But what is wrong with keeping the IV_ values 
fine-grained, and then having the implementation check all of the values and 
fall back to legacy mode if all of the expected values are not met?
(22:11:10) cron2: you once mentioned that the amount of space for IV_ stuff is 
limited, so collapsing stuff sounded like a useful way forward
(22:11:16) jamesyonan: That seems to satisfy the goal of isolating the 
capability description IV_ values from the actual implementation.
(22:12:13) jamesyonan: Actually OpenVPN 3 has an improved implementation of the 
peer info handshake that raises the limit to 64KB without actually changing the 
(22:12:33) cron2: (as a side note, we're sending the client version - so 
IV_RGI6 can go as soon as the client calls itself "2.4")
(22:14:07) jamesyonan: 
(22:14:08) vpnHelper: Title: OpenVPN protocol core : added logic to control 
channel · OpenVPN/openvpn3@2255bab · GitHub (at github.com)
(22:14:56) plaisthos: jamesyonan: what happens if a 3 server sends that to a v3 
(22:16:56) jamesyonan: I believe if a 3 client sends a large message to a 2 
server, it would break.
(22:17:52) jamesyonan: however because this doesn't change the wire protocol, 
it's possible for a 2 server to add this capability without breaking existing 
(22:17:53) syzzer: yes, it currently would
(22:18:09) syzzer: on my list too...
(22:18:27) syzzer: I'll add it to the 2.4 status page
(22:19:17) syzzer: do we believe this is a MUST?  (I do)
(22:20:15) plaisthos: but going incompatible to <= 2.4 isn't a good idea, is it?
(22:20:25) plaisthos: even 2.2 is still around
(22:21:42) syzzer: We might want to refrain from sending that way, but we 
should be able to receive that way
(22:21:56) syzzer: which is the same code needed to support TLS record splitting
(22:22:23) syzzer: (trac #554)
(22:23:30) syzzer: I'll put it under 'minor' for now, we can bump it if needed
(22:23:44) danhunsaker: How soon will you have access to the client version?
(22:24:29) danhunsaker: Because if you know that before sending the server 
IV_*, you can select legacy-vs-large based on that.
(22:26:09) syzzer: either the client or the server has to send something before 
knowing whether the other supports this
(22:28:01) danhunsaker: Indeed.  But who generally goes first?
(22:30:21) jamesyonan: the client goes first on this
(22:31:00) danhunsaker: So the server could decide whether to send a large IV_* 
reply based on version number, no?
(22:31:01) jamesyonan: The client is essentially advertising its capabilities 
with the IV_ peer info, and the server is responding with pushed options.
(22:31:30) jamesyonan: No the IV_ stuff is really a client to server 
(22:32:22) jamesyonan: The options push is the server to client response to the 
IV_ stuff pushed by the client.
(22:32:46) danhunsaker: Got it.
(22:33:35) danhunsaker: So the 2.4 client would need to try a large message, 
fail, and try again with a legacy message to connect to a <2.4 server.
(22:34:39) cron2: re (sorry, had to phone mom...)
(22:34:57) plaisthos: which is bad since tls-timeout is 60s in deafult config
(22:35:17) jamesyonan: Since IV_ peer info is a client to server transmission, 
then implementing the large message receiver on the server doesn't break 
(22:35:53) plaisthos: yeah
(22:35:58) danhunsaker: Not for <2.4c --> >=2.4s
(22:36:08) plaisthos: but sending too much IV_* stuff does :/
(22:36:36) cron2: jamesyonan: how big is the limit in current 2.x code?  "one 
MTU" or "something like 4k"?
(22:36:37) danhunsaker: >=2.4c --> <2.4s is another story.
(22:36:44) jamesyonan: Right, but existing IV_ data isn't exceeding 1024 bytes 
in most cases.
(22:36:57) plaisthos: that is why we want something that is basically 
(22:37:11) ***cron2 has no idea what limits we're talking about...
(22:37:26) cron2: (but it plays into the "username and password bumped to 2048 
bytes" discussion)
(22:37:33) jamesyonan: So a large message sender will only break a legacy 
receiver once the IV_ data exceeds an SSL buffer, which I believe is 1024 bytes.
(22:46:38) mattock: so have we reached a consensus on how to handle this?
(22:46:43) mattock: and when
(22:46:54) syzzer: so, to round this up, am I right that for 2.4, we'll add 
support to receive larger tls records, but won't send larger ones?
(22:47:26) cron2: add support to receive: good plan
(22:47:43) cron2: for sending: needs more thought how to get there in a 
compatible way
(22:49:20) cron2: syzzer: is james' 1024 bytes figure right?
(22:49:45) syzzer: I think so
(22:49:47) syzzer: didn't check
(22:55:08) syzzer: (I'm fighting my jenkins so I can properly run tests before 
(22:56:58) cron2: hrhr :)
(22:57:04) cron2: ok, it's late - any comments on 2.3?
(22:58:16) snair: I would have liked to see the 'block-outside-dns fix' in 
2.3.13 -- but we don't have a review yet.
(23:01:04) cron2: oh, I missed that mail
(23:01:20) cron2: so, recursive routing and block-outside-dns v2
(23:02:05) cron2: (I've found the mail now, just hadn't really seen it before)
(23:03:32) mattock: I have nothing in particular for 2.3.13
(23:04:51) cron2: ok, I'll take a stab at these two patches in the course of 
the week, and then we can aim for 2.3.13 early next week
(23:05:13) mattock: are we still ok with 2.4-alpha1 late this week (or early 
next week)?
(23:05:17) snair: sounds good
(23:05:26) mattock: this IV_PROTO stuff is not "must have" for alpha1, right?
(23:05:38) cron2: if we can get a few test reports on the windows installer, yes
(23:05:52) cron2: (especially people running without gui, without iservice, 
(23:06:10) mattock: yeah
(23:06:21) mattock: any particular corner-cases to test?
(23:06:59) cron2: --server, more than one tap adapter, openvpnserv2
(23:08:57) snair: And, 2.4-alpha1 will get GUI master branch, right. It would 
be good to have the bug fixes I posted in so that alpha-test reports we get 
would reflect unknown bugs.
(23:09:25) cron2: so that would need a new test installer... mattock?
(23:09:37) mattock: could somebody proof-read the IV_* discussion summary: 
(23:09:58) snair: I will also test the open-tun-before-ifconfig patch
(23:10:10) cron2: v2 :)
(23:10:11) mattock: 2.4-alpha1 has openvpn-gui 11 (=master branch right now)
(23:10:29) mattock: yeah, the patch attached to cron2's email
(23:10:30) snair: sure.
(23:11:04) mattock: snair: re: openvpn-gui: I saw the bug fix PR, but did not 
have time to review it
(23:11:08) mattock: will try to do that tomorrow
(23:11:28) snair: thanks.
(23:11:29) mattock: I will generate new 2.4-alpha1 installers as necessary
(23:11:39) syzzer: cron2: we might want to add the 64MB renegotiation for 
64-bit block ciphers to 2.3.next
(23:12:10) danhunsaker: ^-- That's probably a must.
(23:12:12) cron2: that one got sort of stuck, indeed
(23:12:27) syzzer: I'll cook up a patch
(23:12:37) syzzer: should be fairly trivial
(23:13:06) syzzer: would be nice to get it out before the talk (20-something 
(23:14:14) syzzer: also, I'm getting too tired, so ready to call it a day... 
(jenkins has won, for now, but I will tame this beast!)
(23:14:30) cron2: yeah.  bases touched, more on the list...
(23:14:48) snair: ok, g'nite all
(23:14:55) cron2: g'nite :)
(23:15:02) syzzer: g'nite
(23:15:08) danhunsaker: Silly Europe, already letting the sun set.
(23:15:25) danhunsaker: Er.  I mean.  Sleep well, all!
(23:15:45) mattock: good night!
(23:16:06) snair ha abbandonato la stanza.
(23:16:08) lev__: gn!
(23:16:40) plaisthos: good night
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