Date: Wed, 17 Jul 2019 09:09:58 -0700 From: Kevin Bowling <kevin.bowling@kev009.com> To: Michael Tuexen <tuexen@freebsd.org> Cc: Paul <devgs@ukr.net>, Vitalij Satanivskij <satan@ukr.net>, freebsd-net@freebsd.org Subject: Re: Issues with TCP Timestamps allocation Message-ID: <CAK7dMtC1FOD=_4%2B7ZE3B8gmuw3TOk5cCvOjdfPoBx8gD69VgsA@mail.gmail.com> In-Reply-To: <F1CF6E29-E2F5-44FE-B904-DCE93FA91817@freebsd.org> References: <1562599181.734953000.1l9a1d23@frv39.fwdcdn.com> <0C475A01-9BCD-4E4A-9731-09AB919CA9BE@freebsd.org> <1562676414.933145000.z3zteyqp@frv39.fwdcdn.com> <1E9F3F99-C3E9-44DD-AA70-9B11E19D4769@freebsd.org> <20190717074243.GA65665@hell.ukr.net> <CE7F8390-6F56-4550-A8B3-84E0AC31C27C@freebsd.org> <20190717100926.GA24984@hell.ukr.net> <48817BF6-AEDD-4D28-95F8-A4D53E4999B1@freebsd.org> <20190717115502.GA53155@hell.ukr.net> <8763FDC7-8B71-41C3-8D1C-10416DA9A871@freebsd.org> <20190717123251.GA53638@hell.ukr.net> <F1CF6E29-E2F5-44FE-B904-DCE93FA91817@freebsd.org>
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Any knowledge of the endpoints, Linux boxes misconfigured with tcp_tw_recycle? On Wed, Jul 17, 2019 at 5:42 AM Michael Tuexen <tuexen@freebsd.org> wrote: > > On 17. Jul 2019, at 14:32, Vitalij Satanivskij <satan@ukr.net> wrote: > > > > Hmm, looks like with some host's work but not with another > > > > Wed/17.07:/home/satan > > hell:-1522/15:28>curl https://volia.com > /dev/null > > % Total % Received % Xferd Average Speed Time Time Time > Current > > Dload Upload Total Spent Left > Speed > > 100 41519 0 41519 0 0 137k 0 --:--:-- --:--:-- > --:--:-- 137k > > Wed/17.07:/home/satan > > hell:-1523/15:28>curl https://volia.com > /dev/null > > % Total % Received % Xferd Average Speed Time Time Time > Current > > Dload Upload Total Spent Left > Speed > > 0 0 0 0 0 0 0 0 --:--:-- 0:00:53 --:--:-- > 0^C > > Wed/17.07:/home/satan > > hell:-1524/15:29>sysctl net.inet.tcp.rexmit_drop_options > > net.inet.tcp.rexmit_drop_options: 1 > OK, I can confirm that for https://volia.com only a timeout helps. > > What I observed for now is that for the "blocking" to occur is it crucial > that > the server sends the FIN and therefore goes into the TIMEWAIT state. The > timeout > seems to be 60 seconds. > The blocking is also not limited to a single server port. > > I'm not sure yet whether it is a broken end point or a broken middle box. > > Best regards > Michael > > > > But > > > > MT> Interesting. It works for me: > > MT> > > MT> tuexen@head:~ % curl https://vitagramma.com > /dev/null > > MT> % Total % Received % Xferd Average Speed Time Time > Time Current > > MT> Dload Upload Total Spent > Left Speed > > MT> 100 18265 0 18265 0 0 33637 0 --:--:-- --:--:-- > --:--:-- 33575 > > MT> tuexen@head:~ % curl https://vitagramma.com > /dev/null > > MT> % Total % Received % Xferd Average Speed Time Time > Time Current > > MT> Dload Upload Total Spent > Left Speed > > MT> 100 18265 0 18265 0 0 4834 0 --:--:-- 0:00:03 > --:--:-- 4833 > > MT> tuexen@head:~ % curl https://vitagramma.com > /dev/null > > MT> % Total % Received % Xferd Average Speed Time Time > Time Current > > MT> Dload Upload Total Spent > Left Speed > > MT> 100 18265 0 18265 0 0 35813 0 --:--:-- --:--:-- > --:--:-- 35813 > > MT> tuexen@head:~ % time curl https://vitagramma.com > /dev/null > > MT> % Total % Received % Xferd Average Speed Time Time > Time Current > > MT> Dload Upload Total Spent > Left Speed > > MT> 100 18265 0 18265 0 0 48320 0 --:--:-- --:--:-- > --:--:-- 48320 > > MT> 0.012u 0.031s 0:00.39 10.2% 140+245k 0+0io 0pf+0w > > MT> tuexen@head:~ % time curl https://vitagramma.com > /dev/null > > MT> % Total % Received % Xferd Average Speed Time Time > Time Current > > MT> Dload Upload Total Spent > Left Speed > > MT> 100 18265 0 18265 0 0 4592 0 --:--:-- 0:00:03 > --:--:-- 4591 > > MT> 0.031u 0.010s 0:03.99 1.0% 80+140k 0+0io 0pf+0w > > MT> tuexen@head:~ % curl https://vitagramma.com > /dev/null > > MT> % Total % Received % Xferd Average Speed Time Time > Time Current > > MT> Dload Upload Total Spent > Left Speed > > MT> 100 18265 0 18265 0 0 37815 0 --:--:-- --:--:-- > --:--:-- 37737 > > MT> tuexen@head:~ % curl https://vitagramma.com > /dev/null > > MT> % Total % Received % Xferd Average Speed Time Time > Time Current > > MT> Dload Upload Total Spent > Left Speed > > MT> 100 18265 0 18265 0 0 27261 0 --:--:-- --:--:-- > --:--:-- 27220 > > MT> tuexen@head:~ % curl https://vitagramma.com > /dev/null > > MT> % Total % Received % Xferd Average Speed Time Time > Time Current > > MT> Dload Upload Total Spent > Left Speed > > MT> 100 18265 0 18265 0 0 4533 0 --:--:-- 0:00:04 > --:--:-- 4533 > > MT> tuexen@head:~ % curl https://vitagramma.com > /dev/null > > MT> % Total % Received % Xferd Average Speed Time Time > Time Current > > MT> Dload Upload Total Spent > Left Speed > > MT> 100 18265 0 18265 0 0 48320 0 --:--:-- --:--:-- > --:--:-- 48192 > > MT> tuexen@head:~ % curl https://vitagramma.com > /dev/null > > MT> % Total % Received % Xferd Average Speed Time Time > Time Current > > MT> Dload Upload Total Spent > Left Speed > > MT> 100 18265 0 18265 0 0 4746 0 --:--:-- 0:00:03 > --:--:-- 4745 > > MT> tuexen@head:~ % curl https://vitagramma.com > /dev/null > > MT> % Total % Received % Xferd Average Speed Time Time > Time Current > > MT> Dload Upload Total Spent > Left Speed > > MT> 100 18265 0 18265 0 0 4500 0 --:--:-- 0:00:04 > --:--:-- 4767 > > MT> tuexen@head:~ % curl https://vitagramma.com > /dev/null > > MT> % Total % Received % Xferd Average Speed Time Time > Time Current > > MT> Dload Upload Total Spent > Left Speed > > MT> 100 18265 0 18265 0 0 4726 0 --:--:-- 0:00:03 > --:--:-- 4726 > > MT> tuexen@head:~ % curl https://vitagramma.com > /dev/null > > MT> % Total % Received % Xferd Average Speed Time Time > Time Current > > MT> Dload Upload Total Spent > Left Speed > > MT> 100 18265 0 18265 0 0 34268 0 --:--:-- --:--:-- > --:--:-- 34332 > > MT> tuexen@head:~ % > > MT> > > MT> So it either works immediately or with a delay of 3 to 4 seconds... > > MT> > > MT> Best regards > > MT> Michael > > MT> > > > MT> > > > MT> > MT> > > MT> > MT> Option 2: Disable the TCP timestamps (and window scaling) > > MT> > MT> To enable this, you configure on the client > > MT> > MT> sudo sysctl -w net.inet.tcp.rfc1323=0 > > MT> > MT> or put > > MT> > MT> net.inet.tcp.rfc1323=0 > > MT> > MT> in /etc/sysctl.conf > > MT> > MT> and reboot. > > MT> > MT> This disables the timestamp option and window scaling > completely. This allows you to > > MT> > MT> setup the connections without any delay. However, you don't > have the benefits of the > > MT> > MT> extension. > > MT> > MT> > > MT> > MT> Both options don't require any code changes. > > MT> > > > MT> > This option was tested some time before. Yep it's help. But overal > performance of tcp networking ... Let's say to bad :( > > MT> > > > MT> > > > MT> > > > MT> > > > MT> > MT> Best regards > > MT> > MT> Michael > > MT> > MT> > > MT> > MT> > > MT> > MT> > > > MT> > MT> > > > MT> > MT> > MT> > > MT> > MT> > MT> Best regards > > MT> > MT> > MT> Michael > > MT> > MT> > MT> > > > MT> > MT> > MT> > > > MT> > MT> > MT> > > > MT> > MT> > MT> > Michael Tuexen wrote: > > MT> > MT> > MT> > MT> > > MT> > MT> > MT> > MT> > > MT> > MT> > MT> > MT> > On 9. Jul 2019, at 14:58, Paul <devgs@ukr.net> > wrote: > > MT> > MT> > MT> > MT> > > > MT> > MT> > MT> > MT> > Hi Michael, > > MT> > MT> > MT> > MT> > > > MT> > MT> > MT> > MT> > 9 July 2019, 15:34:29, by "Michael Tuexen" < > tuexen@freebsd.org>: > > MT> > MT> > MT> > MT> > > > MT> > MT> > MT> > MT> >> > > MT> > MT> > MT> > MT> >> > > MT> > MT> > MT> > MT> >>> On 8. Jul 2019, at 17:22, Paul <devgs@ukr.net> > wrote: > > MT> > MT> > MT> > MT> >>> > > MT> > MT> > MT> > MT> >>> > > MT> > MT> > MT> > MT> >>> > > MT> > MT> > MT> > MT> >>> 8 July 2019, 17:12:21, by "Michael Tuexen" < > tuexen@freebsd.org>: > > MT> > MT> > MT> > MT> >>> > > MT> > MT> > MT> > MT> >>>>> On 8. Jul 2019, at 15:24, Paul < > devgs@ukr.net> wrote: > > MT> > MT> > MT> > MT> >>>>> > > MT> > MT> > MT> > MT> >>>>> Hi Michael, > > MT> > MT> > MT> > MT> >>>>> > > MT> > MT> > MT> > MT> >>>>> 8 July 2019, 15:53:15, by "Michael Tuexen" < > tuexen@freebsd.org>: > > MT> > MT> > MT> > MT> >>>>> > > MT> > MT> > MT> > MT> >>>>>>> On 8. Jul 2019, at 12:37, Paul < > devgs@ukr.net> wrote: > > MT> > MT> > MT> > MT> >>>>>>> > > MT> > MT> > MT> > MT> >>>>>>> Hi team, > > MT> > MT> > MT> > MT> >>>>>>> > > MT> > MT> > MT> > MT> >>>>>>> Recently we had an upgrade to 12 Stable. > Immediately after, we have started > > MT> > MT> > MT> > MT> >>>>>>> seeing some strange connection > establishment timeouts to some fixed number > > MT> > MT> > MT> > MT> >>>>>>> of external (world) hosts. The issue was > persistent and easy to reproduce. > > MT> > MT> > MT> > MT> >>>>>>> Thanks to a patience and dedication of our > system engineer we have tracked > > MT> > MT> > MT> > MT> >>>>>>> this issue down to a specific commit: > > MT> > MT> > MT> > MT> >>>>>>> > > MT> > MT> > MT> > MT> >>>>>>> > https://svnweb.freebsd.org/base?view=revision&revision=338053 > > MT> > MT> > MT> > MT> >>>>>>> > > MT> > MT> > MT> > MT> >>>>>>> This patch was also back-ported into 11 > Stable: > > MT> > MT> > MT> > MT> >>>>>>> > > MT> > MT> > MT> > MT> >>>>>>> > https://svnweb.freebsd.org/base?view=revision&revision=348435 > > MT> > MT> > MT> > MT> >>>>>>> > > MT> > MT> > MT> > MT> >>>>>>> Among other things this patch changes the > timestamp allocation strategy, > > MT> > MT> > MT> > MT> >>>>>>> by introducing a deterministic randomness > via a hash function that takes > > MT> > MT> > MT> > MT> >>>>>>> into account a random key as well as > source address, source port, dest > > MT> > MT> > MT> > MT> >>>>>>> address and dest port. As the result, > timestamp offsets of different > > MT> > MT> > MT> > MT> >>>>>>> tuples (SA,SP,DA,DP) will be wildly > different and will jump from small > > MT> > MT> > MT> > MT> >>>>>>> to large numbers and back, as long as > something in the tuple changes. > > MT> > MT> > MT> > MT> >>>>>> Hi Paul, > > MT> > MT> > MT> > MT> >>>>>> > > MT> > MT> > MT> > MT> >>>>>> this is correct. > > MT> > MT> > MT> > MT> >>>>>> > > MT> > MT> > MT> > MT> >>>>>> Please note that the same happens with the > old method, if two hosts with > > MT> > MT> > MT> > MT> >>>>>> different uptimes are bind a consumer grade > NAT. > > MT> > MT> > MT> > MT> >>>>> > > MT> > MT> > MT> > MT> >>>>> If NAT does not replace timestamps then yes, > it should be the case. > > MT> > MT> > MT> > MT> >>>>> > > MT> > MT> > MT> > MT> >>>>>>> > > MT> > MT> > MT> > MT> >>>>>>> After performing various tests of hosts > that produce the above mentioned > > MT> > MT> > MT> > MT> >>>>>>> issue we came to conclusion that there are > some interesting implementations > > MT> > MT> > MT> > MT> >>>>>>> that drop SYN packets with timestamps > smaller than the largest timestamp > > MT> > MT> > MT> > MT> >>>>>>> value from streams of all recent or > current connections from a specific > > MT> > MT> > MT> > MT> >>>>>>> address. This looks as some kind of SYN > flood protection. > > MT> > MT> > MT> > MT> >>>>>> This also breaks multiple hosts with > different uptimes behind a consumer > > MT> > MT> > MT> > MT> >>>>>> level NAT talking to such a server. > > MT> > MT> > MT> > MT> >>>>>>> > > MT> > MT> > MT> > MT> >>>>>>> To ensure that each external host is not > going to see a wild jumps of > > MT> > MT> > MT> > MT> >>>>>>> timestamp values I propose a patch that > removes ports from the equation > > MT> > MT> > MT> > MT> >>>>>>> all together, when calculating the > timestamp offset: > > MT> > MT> > MT> > MT> >>>>>>> > > MT> > MT> > MT> > MT> >>>>>>> Index: sys/netinet/tcp_subr.c > > MT> > MT> > MT> > MT> >>>>>>> > =================================================================== > > MT> > MT> > MT> > MT> >>>>>>> --- sys/netinet/tcp_subr.c (revision > 348435) > > MT> > MT> > MT> > MT> >>>>>>> +++ sys/netinet/tcp_subr.c (working > copy) > > MT> > MT> > MT> > MT> >>>>>>> @@ -2224,7 +2224,22 @@ > > MT> > MT> > MT> > MT> >>>>>>> uint32_t > > MT> > MT> > MT> > MT> >>>>>>> tcp_new_ts_offset(struct in_conninfo *inc) > > MT> > MT> > MT> > MT> >>>>>>> { > > MT> > MT> > MT> > MT> >>>>>>> - return (tcp_keyed_hash(inc, > V_ts_offset_secret)); > > MT> > MT> > MT> > MT> >>>>>>> + /* > > MT> > MT> > MT> > MT> >>>>>>> + * Some implementations show a > strange behaviour when a wildly random > > MT> > MT> > MT> > MT> >>>>>>> + * timestamps allocated for > different streams. It seems that only the > > MT> > MT> > MT> > MT> >>>>>>> + * SYN packets are affected. > Observed implementations drop SYN packets > > MT> > MT> > MT> > MT> >>>>>>> + * with timestamps smaller than > the largest timestamp value of all > > MT> > MT> > MT> > MT> >>>>>>> + * recent or current connections > from specific a address. To mitigate > > MT> > MT> > MT> > MT> >>>>>>> + * this we are going to ensure > that each host will always observe > > MT> > MT> > MT> > MT> >>>>>>> + * timestamps as increasing no > matter the stream: by dropping ports > > MT> > MT> > MT> > MT> >>>>>>> + * from the equation. > > MT> > MT> > MT> > MT> >>>>>>> + */ > > MT> > MT> > MT> > MT> >>>>>>> + struct in_conninfo inc_copy = > *inc; > > MT> > MT> > MT> > MT> >>>>>>> + > > MT> > MT> > MT> > MT> >>>>>>> + inc_copy.inc_fport = 0; > > MT> > MT> > MT> > MT> >>>>>>> + inc_copy.inc_lport = 0; > > MT> > MT> > MT> > MT> >>>>>>> + > > MT> > MT> > MT> > MT> >>>>>>> + return (tcp_keyed_hash(&inc_copy, > V_ts_offset_secret)); > > MT> > MT> > MT> > MT> >>>>>>> } > > MT> > MT> > MT> > MT> >>>>>>> > > MT> > MT> > MT> > MT> >>>>>>> /* > > MT> > MT> > MT> > MT> >>>>>>> > > MT> > MT> > MT> > MT> >>>>>>> In any case, the solution of the uptime > leak, implemented in rev338053 is > > MT> > MT> > MT> > MT> >>>>>>> not going to suffer, because a supposed > attacker is currently able to use > > MT> > MT> > MT> > MT> >>>>>>> any fixed values of SP and DP, albeit not > 0, anyway, to remove them out > > MT> > MT> > MT> > MT> >>>>>>> of the equation. > > MT> > MT> > MT> > MT> >>>>>> Can you describe how a peer can compute the > uptime from two observed timestamps? > > MT> > MT> > MT> > MT> >>>>>> I don't see how you can do that... > > MT> > MT> > MT> > MT> >>>>> > > MT> > MT> > MT> > MT> >>>>> Supposed attacker could run a script that > continuously monitors timestamps, > > MT> > MT> > MT> > MT> >>>>> for example via a periodic TCP connection > from a fixed local port (eg 12345) > > MT> > MT> > MT> > MT> >>>>> and a fixed local address to the fixed > victim's address and port (eg 80). > > MT> > MT> > MT> > MT> >>>>> Whenever large discrepancy is observed, > attacker can assume that reboot has > > MT> > MT> > MT> > MT> >>>>> happened (due to V_ts_offset_secret > re-generation), hence the received > > MT> > MT> > MT> > MT> >>>>> timestamp is considered an approximate point > of reboot from which the uptime > > MT> > MT> > MT> > MT> >>>>> can be calculated, until the next reboot and > so on. > > MT> > MT> > MT> > MT> >>>> Ahh, I see. The patch we are talking about is > not intended to protect against > > MT> > MT> > MT> > MT> >>>> continuous monitoring, which is something you > can always do. You could even > > MT> > MT> > MT> > MT> >>>> watch for service availability and detect > reboots. A change of the local key > > MT> > MT> > MT> > MT> >>>> would also look similar to a reboot without a > temporary loss of connectivity. > > MT> > MT> > MT> > MT> >>>> > > MT> > MT> > MT> > MT> >>>> Thanks for the clarification. > > MT> > MT> > MT> > MT> >>>>> > > MT> > MT> > MT> > MT> >>>>>>> > > MT> > MT> > MT> > MT> >>>>>>> There is the list of example hosts that we > were able to reproduce the > > MT> > MT> > MT> > MT> >>>>>>> issue with: > > MT> > MT> > MT> > MT> >>>>>>> > > MT> > MT> > MT> > MT> >>>>>>> curl -v http://88.99.60.171:80 > > MT> > MT> > MT> > MT> >>>>>>> curl -v http://163.172.71.252:80 > > MT> > MT> > MT> > MT> >>>>>>> curl -v http://5.9.242.150:80 > > MT> > MT> > MT> > MT> >>>>>>> curl -v https://185.134.205.105:443 > > MT> > MT> > MT> > MT> >>>>>>> curl -v https://136.243.1.231:443 > > MT> > MT> > MT> > MT> >>>>>>> curl -v https://144.76.196.4:443 > > MT> > MT> > MT> > MT> >>>>>>> curl -v http://94.127.191.194:80 > > MT> > MT> > MT> > MT> >>>>>>> > > MT> > MT> > MT> > MT> >>>>>>> To reproduce, call curl repeatedly with a > same URL some number of times. > > MT> > MT> > MT> > MT> >>>>>>> You are going to see some of the requests > stuck in > > MT> > MT> > MT> > MT> >>>>>>> `* Trying XXX.XXX.XXX.XXX...` > > MT> > MT> > MT> > MT> >>>>>>> > > MT> > MT> > MT> > MT> >>>>>>> For some reason, the easiest way to > reproduce the issue is with nc: > > MT> > MT> > MT> > MT> >>>>>>> > > MT> > MT> > MT> > MT> >>>>>>> $ echo "foooooo" | nc -v 88.99.60.171 80 > > MT> > MT> > MT> > MT> >>>>>>> > > MT> > MT> > MT> > MT> >>>>>>> Only a few such calls are required until > one of them is stuck on connect(): > > MT> > MT> > MT> > MT> >>>>>>> issuing SYN packets with an exponential > backoff. > > MT> > MT> > MT> > MT> >>>>>> Thanks for providing an end-point to test > with. I'll take a look. > > MT> > MT> > MT> > MT> >>>>>> Just to be clear: You are running a FreeBSD > client against one of the above > > MT> > MT> > MT> > MT> >>>>>> servers and experience the problem with the > new timestamp computations. > > MT> > MT> > MT> > MT> >>>>>> > > MT> > MT> > MT> > MT> >>>>>> You are not running arbitrary clients > against a FreeBSD server... > > MT> > MT> > MT> > MT> >>>>> > > MT> > MT> > MT> > MT> >>>>> We are talking about FreeBSD being the > client. Peers that yield this unwanted > > MT> > MT> > MT> > MT> >>>>> behaviour are unknown. Little bit of > tinkering showed that some of them run > > MT> > MT> > MT> > MT> >>>>> Debian: > > MT> > MT> > MT> > MT> >>>>> > > MT> > MT> > MT> > MT> >>>>> telnet 88.99.60.171 22 > > MT> > MT> > MT> > MT> >>>>> Trying 88.99.60.171... > > MT> > MT> > MT> > MT> >>>>> Connected to 88.99.60.171. > > MT> > MT> > MT> > MT> >>>>> Escape character is '^]'. > > MT> > MT> > MT> > MT> >>>>> SSH-2.0-OpenSSH_6.7p1 Debian-5+deb8u3 > > MT> > MT> > MT> > MT> >>>> Also some are hosted by Hetzner, but not all. > I'll will look into > > MT> > MT> > MT> > MT> >>>> this tomorrow, since I'm on a deadline today > (well it is 2am tomorrow > > MT> > MT> > MT> > MT> >>>> morning, to be precise)... > > MT> > MT> > MT> > MT> >>> > > MT> > MT> > MT> > MT> >>> Thanks a lot, I would appreciate that. > > MT> > MT> > MT> > MT> >> Hi Paul, > > MT> > MT> > MT> > MT> >> > > MT> > MT> > MT> > MT> >> I have looked into this. > > MT> > MT> > MT> > MT> >> > > MT> > MT> > MT> > MT> >> * The FreeBSD behaviour is the one which is > specified in the last bullet item > > MT> > MT> > MT> > MT> >> in > https://tools.ietf.org/html/rfc7323#section-5.4 > > MT> > MT> > MT> > MT> >> It is also the one, which is RECOMMENDED in > > MT> > MT> > MT> > MT> >> > https://tools.ietf.org/html/rfc7323#section-7.1 > > MT> > MT> > MT> > MT> >> > > MT> > MT> > MT> > MT> >> * My NAT box (a popular one in Germany) does > NOT rewrite TCP timestamps. > > MT> > MT> > MT> > MT> >> > > MT> > MT> > MT> > MT> >> This means that the host you are referring to > have some sort of protection, > > MT> > MT> > MT> > MT> >> which makes incorrect assumptions. It will also > break multiple hosts behind > > MT> > MT> > MT> > MT> >> a NAT. > > MT> > MT> > MT> > MT> >> > > MT> > MT> > MT> > MT> >> I can run > > MT> > MT> > MT> > MT> >> curl -v http://88.99.60.171:80 > > MT> > MT> > MT> > MT> >> in a loop without any problems from a FreeBSD > head system. I tested 1000 > > MT> > MT> > MT> > MT> >> iterations or so. The TS.val is jumping up and > down as expected. > > MT> > MT> > MT> > MT> >> I'm wondering why you are observing errors in > this case, too. > > MT> > MT> > MT> > MT> >> > > MT> > MT> > MT> > MT> >> However, doing something like > > MT> > MT> > MT> > MT> >> echo "foooooo" | nc -v 88.99.60.171 80 > > MT> > MT> > MT> > MT> >> triggers the problem. > > MT> > MT> > MT> > MT> >> > > MT> > MT> > MT> > MT> >> So I think there is some functionality (in a > middlebox or running on the host), > > MT> > MT> > MT> > MT> >> which incorrectly assume monotonic timestamps > between multiple TCP connections > > MT> > MT> > MT> > MT> >> coming from the same IP address, but only in > case of errors at the application layer. > > MT> > MT> > MT> > MT> > > > MT> > MT> > MT> > MT> > Yeah, exactly, some hosts seem to enable this > only in case of an error in HTTP > > MT> > MT> > MT> > MT> > communication (some smart proxy?). However, > there are some that behave this way > > MT> > MT> > MT> > MT> > regardless of errors, for example these: > > MT> > MT> > MT> > MT> > > > MT> > MT> > MT> > MT> > curl -v https://185.134.205.105:443 > > MT> > MT> > MT> > MT> > curl -v https://136.243.1.231:443 > > MT> > MT> > MT> > MT> Wireshark sees an Encrypted Alert in both cases. > So I guess this is another indication > > MT> > MT> > MT> > MT> of "error at the application layer". > > MT> > MT> > MT> > MT> > > > MT> > MT> > MT> > MT> >> > > MT> > MT> > MT> > MT> >> Do you have any insights whether the hosts you > are listed share something in > > MT> > MT> > MT> > MT> >> common. Some of them are hosted by Hetzner, but > not all. > > MT> > MT> > MT> > MT> > > > MT> > MT> > MT> > MT> > Nope. A whole set of endpoints that we have > detected so far is pretty diverse, > > MT> > MT> > MT> > MT> > containing a lot of different locations > geographically, as well as different > > MT> > MT> > MT> > MT> > hosters. > > MT> > MT> > MT> > MT> OK. Thanks for the clarification. > > MT> > MT> > MT> > MT> > > > MT> > MT> > MT> > MT> >> > > MT> > MT> > MT> > MT> >> I think in general, it is the correct thing to > include the port numbers in > > MT> > MT> > MT> > MT> >> the offset computation. We might add a sysctl > variable to control the inclusion. > > MT> > MT> > MT> > MT> >> This would allow interworking with broken > middleboxes. > > MT> > MT> > MT> > MT> > > > MT> > MT> > MT> > MT> > Yeah, I completely agree that these rare cases > should not dictate the implementation. > > MT> > MT> > MT> > MT> > But an ability to enable a work-around via > sysctl would be greatly appreciated. > > MT> > MT> > MT> > MT> > Currently we are unable to roll-out the upgrade > across all servers because of this > > MT> > MT> > MT> > MT> > issue: even though it happens not so often, a > lot of requests from our users > > MT> > MT> > MT> > MT> > get stuck or fail all together. For example, a > host 185.134.205.105 is a kind of > > MT> > MT> > MT> > MT> > social network that our proxy servers connect to > so securely access to content, > > MT> > MT> > MT> > MT> > such as images, on behalf of our users. > > MT> > MT> > MT> > MT> > > > MT> > MT> > MT> > MT> >> > > MT> > MT> > MT> > MT> >> Please note, this does not fix the case of > multiple clients behind a NAT. > > MT> > MT> > MT> > MT> > > > MT> > MT> > MT> > MT> > Yeah, that's true. Fortunately we don't use NAT. > > MT> > MT> > MT> > MT> > > > MT> > MT> > MT> > MT> >> > > MT> > MT> > MT> > MT> >> I'm also trying to figure out how and why Linux > and Windows are handling this. > > MT> > MT> > MT> > MT> > > > MT> > MT> > MT> > MT> > Thanks for bothering! > > MT> > MT> > MT> > MT> Will let you know what I figure out. > > MT> > MT> > MT> > MT> > > MT> > MT> > MT> > MT> Best regards > > MT> > MT> > MT> > MT> Michael > > MT> > MT> > MT> > MT> > > > MT> > MT> > MT> > MT> >> > > MT> > MT> > MT> > MT> >> Best regards > > MT> > MT> > MT> > MT> >> Michael > > MT> > MT> > MT> > MT> >> > > MT> > MT> > MT> > MT> >>> > > MT> > MT> > MT> > MT> >>>> > > MT> > MT> > MT> > MT> >>>> Best regards > > MT> > MT> > MT> > MT> >>>> Michael > > MT> > MT> > MT> > MT> >>>>> > > MT> > MT> > MT> > MT> >>>>> > > MT> > MT> > MT> > MT> >>>>>> > > MT> > MT> > MT> > MT> >>>>>> Best regards > > MT> > MT> > MT> > MT> >>>>>> Michael > > MT> > MT> > MT> > MT> >>>>>> > > MT> > MT> > MT> > MT> >>>>>> > > MT> > MT> > MT> > MT> >>>> > > MT> > MT> > MT> > MT> >>>> > > MT> > MT> > MT> > MT> >> > > MT> > MT> > MT> > MT> >> > > MT> > MT> > MT> > MT> > > MT> > MT> > MT> > MT> _______________________________________________ > > MT> > MT> > MT> > MT> freebsd-net@freebsd.org mailing list > > MT> > MT> > MT> > MT> > https://lists.freebsd.org/mailman/listinfo/freebsd-net > > MT> > MT> > MT> > MT> To unsubscribe, send any mail to " > freebsd-net-unsubscribe@freebsd.org" > > MT> > MT> > MT> > > MT> > MT> > MT> _______________________________________________ > > MT> > MT> > MT> freebsd-net@freebsd.org mailing list > > MT> > MT> > MT> https://lists.freebsd.org/mailman/listinfo/freebsd-net > > MT> > MT> > MT> To unsubscribe, send any mail to " > freebsd-net-unsubscribe@freebsd.org" > > MT> > MT> > > MT> > _______________________________________________ > > MT> > freebsd-net@freebsd.org mailing list > > MT> > https://lists.freebsd.org/mailman/listinfo/freebsd-net > > MT> > To unsubscribe, send any mail to " > freebsd-net-unsubscribe@freebsd.org" > > MT> > > _______________________________________________ > > freebsd-net@freebsd.org mailing list > > https://lists.freebsd.org/mailman/listinfo/freebsd-net > > To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org" > > _______________________________________________ > freebsd-net@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-net > To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org" >
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