Tincd cannot flush and resets the connection

Mon Sep 21 11:13:33 CEST 2009

Hello,

Sorry to bother you, but I have been searching but cannot find any
reason why my mysql sessions get stuck. (over tinc en over normal
connections). Tinc gets stuck and needs to reconnect,, over normal
connections only that session gets stuck and a retry works.

I did find a difference using tcpdump between a working request en one
that is failing. Notice the  {1532:2304} on the last line of the failing
session. Could this have something to do with fragmentation? I am
searching google to try and find what the numbers between {} mean.

I don't think its because my provider is capping things. I tried tinc on
port 110.

I know this is not a tinc problem (al though I things it's weird that
tinc gets stuck too) But maybe you have any hints where to look next. 

Thanks for your help

Regards

Hans de Groot

a succesfull request:

14:28:10.590419 IP 81.xxx.xxx.xxx.51127 > 87.xxx.xxx.xxx.mysql: S 4162371042:4162371042(0) win 5840 <mss 1460,sackOK,timestamp 1200139766 0,nop,wscale 4>
14:28:10.643279 IP 87.xxx.xxx.xxx.mysql > 81.xxx.xxx.xxx.51127: S 2130799617:2130799617(0) ack 4162371043 win 5792 <mss 1452,sackOK,timestamp 461130992 1200139766,nop,wscale 4>
14:28:10.643494 IP 81.xxx.xxx.xxx.51127 > 87.xxx.xxx.xxx.mysql: . ack 1 win 365 <nop,nop,timestamp 1200139819 461130992>
14:28:10.679248 IP 87.xxx.xxx.xxx.mysql > 81.xxx.xxx.xxx.51127: P 1:57(56) ack 1 win 362 <nop,nop,timestamp 461131019 1200139819>
14:28:10.679623 IP 81.xxx.xxx.xxx.51127 > 87.xxx.xxx.xxx.mysql: . ack 57 win 365 <nop,nop,timestamp 1200139855 461131019>
14:28:10.679826 IP 81.xxx.xxx.xxx.51127 > 87.xxx.xxx.xxx.mysql: P 1:82(81) ack 57 win 365 <nop,nop,timestamp 1200139856 461131019>
14:28:10.709185 IP 87.xxx.xxx.xxx.mysql > 81.xxx.xxx.xxx.51127: . ack 82 win 362 <nop,nop,timestamp 461131053 1200139856>
14:28:10.710420 IP 87.xxx.xxx.xxx.mysql > 81.xxx.xxx.xxx.51127: P 57:62(5) ack 82 win 362 <nop,nop,timestamp 461131053 1200139856>
14:28:10.710786 IP 81.xxx.xxx.xxx.51127 > 87.xxx.xxx.xxx.mysql: P 82:95(13) ack 62 win 365 <nop,nop,timestamp 1200139887 461131053>
14:28:10.743884 IP 87.xxx.xxx.xxx.mysql > 81.xxx.xxx.xxx.51127: P 62:73(11) ack 95 win 362 <nop,nop,timestamp 461131087 1200139887>
14:28:10.744520 IP 81.xxx.xxx.xxx.51127 > 87.xxx.xxx.xxx.mysql: P 95:116(21) ack 73 win 365 <nop,nop,timestamp 1200139920 461131087>
14:28:10.776837 IP 87.xxx.xxx.xxx.mysql > 81.xxx.xxx.xxx.51127: P 73:84(11) ack 116 win 362 <nop,nop,timestamp 461131120 1200139920>
14:28:10.778782 IP 81.xxx.xxx.xxx.51127 > 87.xxx.xxx.xxx.mysql: P 116:161(45) ack 84 win 365 <nop,nop,timestamp 1200139955 461131120>
14:28:10.821373 IP 87.xxx.xxx.xxx.mysql > 81.xxx.xxx.xxx.51127: . 84:1524(1440) ack 161 win 362 <nop,nop,timestamp 461131152 1200139955>
14:28:10.827979 IP 87.xxx.xxx.xxx.mysql > 81.xxx.xxx.xxx.51127: P 1524:2283(759) ack 161 win 362 <nop,nop,timestamp 461131152 1200139955>
14:28:10.828155 IP 81.xxx.xxx.xxx.51127 > 87.xxx.xxx.xxx.mysql: . ack 2283 win 726 <nop,nop,timestamp 1200140004 461131152>
14:28:10.831245 IP 81.xxx.xxx.xxx.51127 > 87.xxx.xxx.xxx.mysql: P 161:277(116) ack 2283 win 726 <nop,nop,timestamp 1200140007 461131152>
14:28:10.905950 IP 87.xxx.xxx.xxx.mysql > 81.xxx.xxx.xxx.51127: P 2283:3226(943) ack 277 win 362 <nop,nop,timestamp 461131254 1200140007>
14:28:10.909652 IP 81.xxx.xxx.xxx.51127 > 87.xxx.xxx.xxx.mysql: P 277:282(5) ack 3226 win 906 <nop,nop,timestamp 1200140086 461131254>
14:28:10.909828 IP 81.xxx.xxx.xxx.51127 > 87.xxx.xxx.xxx.mysql: F 282:282(0) ack 3226 win 906 <nop,nop,timestamp 1200140086 461131254>
14:28:10.951637 IP 87.xxx.xxx.xxx.mysql > 81.xxx.xxx.xxx.51127: F 3226:3226(0) ack 283 win 362 <nop,nop,timestamp 461131301 1200140086>
14:28:10.951708 IP 81.xxx.xxx.xxx.51127 > 87.xxx.xxx.xxx.mysql: . ack 3227 win 906 <nop,nop,timestamp 1200140128 461131301>

a failing request:
14:36:11.495996 IP 81.xxx.xxx.xxx.50502 > 87.xxx.xxx.xxx.mysql: S 370742438:370742438(0) win 5840 <mss 1460,sackOK,timestamp 1200620760 0,nop,wscale 4>
14:36:11.530824 IP 87.xxx.xxx.xxx.mysql > 81.xxx.xxx.xxx.50502: S 2651192070:2651192070(0) ack 370742439 win 5792 <mss 1452,sackOK,timestamp 461611907 1200620760,nop,wscale 4>
14:36:11.530921 IP 81.xxx.xxx.xxx.50502 > 87.xxx.xxx.xxx.mysql: . ack 1 win 365 <nop,nop,timestamp 1200620795 461611907>
14:36:11.566439 IP 87.xxx.xxx.xxx.mysql > 81.xxx.xxx.xxx.50502: P 1:57(56) ack 1 win 362 <nop,nop,timestamp 461611941 1200620795>
14:36:11.566627 IP 81.xxx.xxx.xxx.50502 > 87.xxx.xxx.xxx.mysql: . ack 57 win 365 <nop,nop,timestamp 1200620831 461611941>
14:36:11.567027 IP 81.xxx.xxx.xxx.50502 > 87.xxx.xxx.xxx.mysql: P 1:82(81) ack 57 win 365 <nop,nop,timestamp 1200620831 461611941>
14:36:11.587696 IP 87.xxx.xxx.xxx.mysql > 81.xxx.xxx.xxx.50502: . ack 82 win 362 <nop,nop,timestamp 461611977 1200620831>
14:36:11.587701 IP 87.xxx.xxx.xxx.mysql > 81.xxx.xxx.xxx.50502: P 57:62(5) ack 82 win 362 <nop,nop,timestamp 461611977 1200620831>
14:36:11.588093 IP 81.xxx.xxx.xxx.50502 > 87.xxx.xxx.xxx.mysql: P 82:95(13) ack 62 win 365 <nop,nop,timestamp 1200620852 461611977>
14:36:11.617600 IP 87.xxx.xxx.xxx.mysql > 81.xxx.xxx.xxx.50502: P 62:73(11) ack 95 win 362 <nop,nop,timestamp 461612013 1200620852>
14:36:11.618198 IP 81.xxx.xxx.xxx.50502 > 87.xxx.xxx.xxx.mysql: P 95:116(21) ack 73 win 365 <nop,nop,timestamp 1200620883 461612013>
14:36:11.649549 IP 87.xxx.xxx.xxx.mysql > 81.xxx.xxx.xxx.50502: P 73:84(11) ack 116 win 362 <nop,nop,timestamp 461612047 1200620883>
14:36:11.651392 IP 81.xxx.xxx.xxx.50502 > 87.xxx.xxx.xxx.mysql: P 116:161(45) ack 84 win 365 <nop,nop,timestamp 1200620916 461612047>
14:36:11.695304 IP 87.xxx.xxx.xxx.mysql > 81.xxx.xxx.xxx.50502: P 1532:2304(772) ack 161 win 362 <nop,nop,timestamp 461612080 1200620916>
14:36:11.695591 IP 81.xxx.xxx.xxx.50502 > 87.xxx.xxx.xxx.mysql: . ack 84 win 365 <nop,nop,timestamp 1200620960 461612047,nop,nop,sack 1 {1532:2304}>

On Mon, 7 Sep 2009 13:56:31 +0200
Guus Sliepen <guus at tinc-vpn.org> wrote:

> On Mon, Sep 07, 2009 at 01:09:40PM +0200, Hans de Groot wrote:
> 
> > I tried your settings but it did not help.
> > 
> > I switched back to a direct mysql connection from the master001 to the
> > client001 via port forwarding and gues what? I have the same problem
> > here. (some times it works sometimes not)
> > 
> > Only there is a difference, only the mysql session gets stuck,. ping and
> > other connectivity keeps working. In the tinc setup the whole tinc
> > interface/route got reset. (network unreachable)
> 
> Ok, that makes sense... my guess is that TCP connections other than to/from
> port 80 are being cut off, maybe in an attempt to "enhance" your Internet
> experience by throttling peer-to-peer traffic. You could try running tincd on
> master001 on a different port, like 21, 22, 23, 25, 53, 80, 443, or any other
> very common, non-p2p port that is not in use on that machine.
> 
> -- 
> Met vriendelijke groet / with kind regards,
>      Guus Sliepen <guus at tinc-vpn.org>

--- 
Hans de Groot 
Email: hansg at dandy.nl   www: http://www.dandy.nl