Intermittent TCP connect issues when using tinc 1.0.23 and IPv6

[tomp at tomp.co.uk]

I can confirm this issue is also occurring when using tinc 1.1pre9 with 
elliptic encryption.

On 2013-11-28 12:12, tomp at tomp.co.uk wrote:
> Here's some more info, as a timeout just occurred using rsync from
> rsukmhb to rps sites:
> 
> Nov 28 11:59:01 rsuk-mhb-pubweb101 php: ict-pubweb [SyncSites]
> (21294) Info: Plugin started
> Nov 28 11:59:01 rsuk-mhb-pubweb101 php: ict-pubweb [SyncSites]
> (21294) Info: Last sync build time: 2013-11-27 09:50:40
> Nov 28 11:59:16 rsuk-mhb-pubweb101 php: ict-pubweb [SyncSites]
> (21294) Error: Rsync failed: rsync error: timeout waiting for daemon
> connection (code 35) at socket.c(279) [receiver=3.0.6]
> Nov 28 11:59:16 rsuk-mhb-pubweb101 php: ict-pubweb [SyncSites]
> (21294) Info: Plugin stopped
> 
> Rsync is configured with a connection timeout of 15s, so the
> connection was started at 11:59:01 and timed out at 11:59:16.
> 
> At the same time our import cron process ran from rps to the same
> server that was running the rsync client:
> 
> Nov 28 11:59:01 rsuk-mhb-pubweb101 httpd: pubweb.infinity.local
> rsuk-mhb-pubweb101.ictnw.net 2001:1b40:5600:1::76 - ict-pubweb
> [28/Nov/2013:11:59:01 +0000] "GET
> /v1/cmsEvents?limit=1000&sort%5B0%5D=rowId-asc&filter%5B0%5D=siteId-in-value-2&filter%5B1%5D=rowId-gt-value-933&filter%5B2%5D=eventType-eq-value-lead
> HTTP/1.0" 200 - "-" "Icc HTTP Client"
> 
> I am running tinc with debug mode 5 on both firewalls so here is a
> sample of the logs from both at that time:
> 
> rsukmhb site (where rsync client is):
> -----------------------------------------
> 
> [thomas.parrott at rsuk-mhb-fw01 ~]$ grep '11:59:' /var/log/messages
> 
> Nov 28 11:59:01 rsuk-mhb-fw01 tinc.dcvpn[24911]: Clamping MSS of
> packet from rsukmhb to rps to 1369
> Nov 28 11:59:01 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 86
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:01 rsuk-mhb-fw01 tinc.dcvpn[24911]: Clamping MSS of
> packet from rsukmhb to rps to 1369
> Nov 28 11:59:01 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 86
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:01 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:01 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of
> 224 bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:01 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:01 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:01 rsuk-mhb-fw01 tinc.dcvpn[24911]: Clamping MSS of
> packet from rsukmhb to rps to 1369
> Nov 28 11:59:01 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 86
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:01 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:01 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 88
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:01 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:01 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 87
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:01 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of
> 108 bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:01 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 82
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:01 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of
> 136 bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:02 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:02 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:02 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 82
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:02 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:02 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:02 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:02 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 79
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:02 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:02 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:02 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:02 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 89
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:02 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 89
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:02 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:02 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:02 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 80
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:02 rsuk-mhb-fw01 tinc.dcvpn[24911]: Clamping MSS of
> packet from rsukmhb to rps to 1369
> Nov 28 11:59:02 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 86
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:02 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:02 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:02 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 79
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:02 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:03 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of
> 139 bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:04 rsuk-mhb-fw01 tinc.dcvpn[24911]: Clamping MSS of
> packet from rsukmhb to rps to 1369
> Nov 28 11:59:04 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 86
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:08 rsuk-mhb-fw01 tinc.dcvpn[24911]: Clamping MSS of
> packet from rsukmhb to rps to 1369
> Nov 28 11:59:08 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 86
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:10 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of
> 118 bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:11 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of
> 118 bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:11 rsuk-mhb-fw01 tinc.dcvpn[24911]: Clamping MSS of
> packet from rsukmhb to rps to 1369
> Nov 28 11:59:11 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 86
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:11 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:11 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of
> 224 bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:11 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:11 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:12 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of
> 118 bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:13 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of
> 118 bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:14 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of
> 118 bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:16 rsuk-mhb-fw01 tinc.dcvpn[24911]: Clamping MSS of
> packet from rsukmhb to rps to 1369
> Nov 28 11:59:16 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 86
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:21 rsuk-mhb-fw01 tinc.dcvpn[24911]: Clamping MSS of
> packet from rsukmhb to rps to 1369
> Nov 28 11:59:21 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 86
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:21 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:21 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of
> 224 bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:21 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:21 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:29 rsuk-mhb-fw01 tinc.dcvpn[24911]: Clamping MSS of
> packet from rsukmhb to rps to 1369
> Nov 28 11:59:29 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 86
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:29 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:29 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of
> 224 bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:29 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:29 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:34 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of
> 129 bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:39 rsuk-mhb-fw01 tinc.dcvpn[24911]: Clamping MSS of
> packet from rsukmhb to rps to 1369
> Nov 28 11:59:39 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 86
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:39 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:39 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of
> 224 bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:39 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:39 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:42 rsuk-mhb-fw01 tinc.dcvpn[24911]: Got MTU probe length
> 1443 from rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:42 rsuk-mhb-fw01 tinc.dcvpn[24911]: Got MTU probe length
> 1443 from rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:42 rsuk-mhb-fw01 tinc.dcvpn[24911]: Got MTU probe length
> 1443 from rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:43 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending MTU probe
> length 1451 to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:43 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending MTU probe
> length 1443 to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:43 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending MTU probe
> length 1443 to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:43 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending MTU probe
> length 1443 to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:43 rsuk-mhb-fw01 tinc.dcvpn[24911]: Got MTU probe length
> 1443 from rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:43 rsuk-mhb-fw01 tinc.dcvpn[24911]: Got MTU probe length
> 1443 from rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:43 rsuk-mhb-fw01 tinc.dcvpn[24911]: Got MTU probe length
> 1443 from rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:43 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of
> 118 bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:44 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of
> 118 bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:45 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of
> 118 bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:46 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of
> 118 bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:47 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of
> 118 bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:49 rsuk-mhb-fw01 tinc.dcvpn[24911]: Clamping MSS of
> packet from rsukmhb to rps to 1369
> Nov 28 11:59:49 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 86
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:49 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:49 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of
> 224 bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:49 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:49 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:55 rsuk-mhb-fw01 tinc.dcvpn[24911]: Clamping MSS of
> packet from rsukmhb to rps to 1369
> Nov 28 11:59:55 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 86
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:55 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of
> 112 bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:55 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:55 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of
> 106 bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:55 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 89
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:55 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> Nov 28 11:59:55 rsuk-mhb-fw01 tinc.dcvpn[24911]: Sending packet of 74
> bytes to rps (2001:1b40:5000:9::2 port 655)
> 
> rps site (where rsync server is):
> -----------------------------------------
> 
> [thomas.parrott at rps-fw03 ~]$ grep '11:59:' /var/log/messages
> Nov 28 11:59:01 rps-fw03 tinc.dcvpn[17321]: Clamping MSS of packet
> from rps to rsukmhb to 1369
> Nov 28 11:59:01 rps-fw03 tinc.dcvpn[17321]: Sending packet of 86
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:01 rps-fw03 tinc.dcvpn[17321]: Sending packet of 74
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:01 rps-fw03 tinc.dcvpn[17321]: Sending packet of 433
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:01 rps-fw03 tinc.dcvpn[17321]: Sending packet of 74
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:01 rps-fw03 tinc.dcvpn[17321]: Sending packet of 74
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:01 rps-fw03 tinc.dcvpn[17321]: Clamping MSS of packet
> from rps to rsukmhb to 1369
> Nov 28 11:59:01 rps-fw03 tinc.dcvpn[17321]: Sending packet of 86
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:01 rps-fw03 tinc.dcvpn[17321]: Sending packet of 74
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:01 rps-fw03 tinc.dcvpn[17321]: Sending packet of 88
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:01 rps-fw03 tinc.dcvpn[17321]: Sending packet of 115
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:01 rps-fw03 tinc.dcvpn[17321]: Sending packet of 86
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:01 rps-fw03 tinc.dcvpn[17321]: Sending packet of 74
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:01 rps-fw03 tinc.dcvpn[17321]: Sending packet of 74
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:01 rps-fw03 tinc.dcvpn[17321]: Sending packet of 75
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:02 rps-fw03 tinc.dcvpn[17321]: Sending packet of 78
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:02 rps-fw03 tinc.dcvpn[17321]: Sending packet of 78
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:02 rps-fw03 tinc.dcvpn[17321]: Sending packet of 1443
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:02 rps-fw03 tinc.dcvpn[17321]: Sending packet of 1443
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:02 rps-fw03 tinc.dcvpn[17321]: Sending packet of 1443
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:02 rps-fw03 tinc.dcvpn[17321]: Sending packet of 1443
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:02 rps-fw03 tinc.dcvpn[17321]: Sending packet of 1443
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:02 rps-fw03 tinc.dcvpn[17321]: Sending packet of 1417
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:02 rps-fw03 tinc.dcvpn[17321]: Sending packet of 1443
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:02 rps-fw03 tinc.dcvpn[17321]: Sending packet of 1443
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:02 rps-fw03 tinc.dcvpn[17321]: Sending packet of 1443
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:02 rps-fw03 tinc.dcvpn[17321]: Sending packet of 1443
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:02 rps-fw03 tinc.dcvpn[17321]: Sending packet of 1443
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:02 rps-fw03 tinc.dcvpn[17321]: Sending packet of 1443
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:02 rps-fw03 tinc.dcvpn[17321]: Sending packet of 1035
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:02 rps-fw03 tinc.dcvpn[17321]: Sending packet of 74
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:02 rps-fw03 tinc.dcvpn[17321]: Sending packet of 89
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:02 rps-fw03 tinc.dcvpn[17321]: Sending packet of 89
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:02 rps-fw03 tinc.dcvpn[17321]: Sending packet of 79
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:02 rps-fw03 tinc.dcvpn[17321]: Sending packet of 98
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:02 rps-fw03 tinc.dcvpn[17321]: Sending packet of 74
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:02 rps-fw03 tinc.dcvpn[17321]: Sending packet of 74
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:03 rps-fw03 tinc.dcvpn[17321]: Sending packet of 107
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:10 rps-fw03 tinc.dcvpn[17321]: Sending packet of 118
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:11 rps-fw03 tinc.dcvpn[17321]: Sending packet of 118
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:11 rps-fw03 tinc.dcvpn[17321]: Clamping MSS of packet
> from rps to rsukmhb to 1369
> Nov 28 11:59:11 rps-fw03 tinc.dcvpn[17321]: Sending packet of 86
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:11 rps-fw03 tinc.dcvpn[17321]: Sending packet of 74
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:11 rps-fw03 tinc.dcvpn[17321]: Sending packet of 433
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:11 rps-fw03 tinc.dcvpn[17321]: Sending packet of 74
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:11 rps-fw03 tinc.dcvpn[17321]: Sending packet of 74
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:12 rps-fw03 tinc.dcvpn[17321]: Sending packet of 118
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:13 rps-fw03 tinc.dcvpn[17321]: Sending packet of 118
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:14 rps-fw03 tinc.dcvpn[17321]: Sending packet of 118
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:21 rps-fw03 tinc.dcvpn[17321]: Clamping MSS of packet
> from rps to rsukmhb to 1369
> Nov 28 11:59:21 rps-fw03 tinc.dcvpn[17321]: Sending packet of 86
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:21 rps-fw03 tinc.dcvpn[17321]: Sending packet of 74
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:21 rps-fw03 tinc.dcvpn[17321]: Sending packet of 433
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:21 rps-fw03 tinc.dcvpn[17321]: Sending packet of 74
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:21 rps-fw03 tinc.dcvpn[17321]: Sending packet of 74
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:29 rps-fw03 tinc.dcvpn[17321]: Clamping MSS of packet
> from rps to rsukmhb to 1369
> Nov 28 11:59:29 rps-fw03 tinc.dcvpn[17321]: Sending packet of 86
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:29 rps-fw03 tinc.dcvpn[17321]: Sending packet of 74
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:29 rps-fw03 tinc.dcvpn[17321]: Sending packet of 433
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:29 rps-fw03 tinc.dcvpn[17321]: Sending packet of 74
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:29 rps-fw03 tinc.dcvpn[17321]: Sending packet of 74
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:34 rps-fw03 tinc.dcvpn[17321]: Sending packet of 122
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:39 rps-fw03 tinc.dcvpn[17321]: Clamping MSS of packet
> from rps to rsukmhb to 1369
> Nov 28 11:59:39 rps-fw03 tinc.dcvpn[17321]: Sending packet of 86
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:39 rps-fw03 tinc.dcvpn[17321]: Sending packet of 74
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:39 rps-fw03 tinc.dcvpn[17321]: Sending packet of 433
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:39 rps-fw03 tinc.dcvpn[17321]: Sending packet of 74
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:39 rps-fw03 tinc.dcvpn[17321]: Sending packet of 74
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:42 rps-fw03 tinc.dcvpn[17321]: Sending MTU probe length
> 1451 to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:42 rps-fw03 tinc.dcvpn[17321]: Sending MTU probe length
> 1443 to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:42 rps-fw03 tinc.dcvpn[17321]: Sending MTU probe length
> 1443 to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:42 rps-fw03 tinc.dcvpn[17321]: Sending MTU probe length
> 1443 to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:42 rps-fw03 tinc.dcvpn[17321]: Got MTU probe length 1443
> from rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:42 rps-fw03 tinc.dcvpn[17321]: Got MTU probe length 1443
> from rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:42 rps-fw03 tinc.dcvpn[17321]: Got MTU probe length 1443
> from rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:43 rps-fw03 tinc.dcvpn[17321]: Got MTU probe length 1443
> from rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:43 rps-fw03 tinc.dcvpn[17321]: Got MTU probe length 1443
> from rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:43 rps-fw03 tinc.dcvpn[17321]: Got MTU probe length 1443
> from rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:43 rps-fw03 tinc.dcvpn[17321]: Sending packet of 118
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:44 rps-fw03 tinc.dcvpn[17321]: Sending packet of 118
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:45 rps-fw03 tinc.dcvpn[17321]: Sending packet of 118
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:46 rps-fw03 tinc.dcvpn[17321]: Sending packet of 118
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:47 rps-fw03 tinc.dcvpn[17321]: Sending packet of 118
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:49 rps-fw03 tinc.dcvpn[17321]: Clamping MSS of packet
> from rps to rsukmhb to 1369
> Nov 28 11:59:49 rps-fw03 tinc.dcvpn[17321]: Sending packet of 86
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:49 rps-fw03 tinc.dcvpn[17321]: Sending packet of 74
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:49 rps-fw03 tinc.dcvpn[17321]: Sending packet of 433
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:49 rps-fw03 tinc.dcvpn[17321]: Sending packet of 74
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:49 rps-fw03 tinc.dcvpn[17321]: Sending packet of 74
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:55 rps-fw03 tinc.dcvpn[17321]: Clamping MSS of packet
> from rps to rsukmhb to 1369
> Nov 28 11:59:55 rps-fw03 tinc.dcvpn[17321]: Sending packet of 86
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:55 rps-fw03 tinc.dcvpn[17321]: Sending packet of 74
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:55 rps-fw03 tinc.dcvpn[17321]: Sending packet of 74
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:55 rps-fw03 tinc.dcvpn[17321]: Sending packet of 105
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:55 rps-fw03 tinc.dcvpn[17321]: Sending packet of 80
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:55 rps-fw03 tinc.dcvpn[17321]: Sending packet of 74
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> Nov 28 11:59:55 rps-fw03 tinc.dcvpn[17321]: Sending packet of 74
> bytes to rsukmhb (2001:1b40:5000:19::2 port 655)
> 
> Neither firewalls are heaving loaded.
> 
> Thanks
> Tom
> 
> 
> On 2013-11-28 11:49, tomp at Tomp.co.uk wrote:
>> Hi,
>> I am using tinc 1.0.23 in router mode and am having trouble with
>> intermittent TCP connect timeouts that do not occur when routing the
>> TCP over the internet directly.
>> I am using a pure IPv6 setup (i.e direct IPv6 connections, and
>> tunneled IPv6 subnets).
>> My configs are as follows:
>> Site 1:
>> -----------------------
>> tinc.conf:
>> Name = rsukmhb
>> AddressFamily = ipv6
>> BindToAddress = 2001:1b40:5000:19::2
>> ConnectTo = rps
>> IffOneQueue = yes
>> tinc-up:
>> #!/bin/sh
>> logger -t tinc Bringing up interface $INTERFACE
>> ip -6 link set "$INTERFACE" up
>> ip -6 link set "$INTERFACE" txqueuelen 10
>> ip -6 addr add fdd1:c52a:3c24:3384::2/64 dev "$INTERFACE"
>> subnet-up:
>> #!/bin/sh
>> [ -z "$NAME" ] && exit 0
>> [ "$NAME" = "$NODE" ] && exit 0
>> logger -t tinc Adding route to $SUBNET for $NODE on $NAME
>> ip -6 route replace $SUBNET dev $INTERFACE
>> Site 2:
>> -----------------------
>> tinc.conf:
>> Name = rps
>> AddressFamily = ipv6
>> BindToAddress = 2001:1b40:5000:9::2
>> ConnectTo = rsukmhb
>> IffOneQueue = yes
>> tinc-up:
>> #!/bin/sh
>> logger -t tinc Bringing up interface $INTERFACE
>> ip -6 link set "$INTERFACE" up
>> ip -6 link set "$INTERFACE" txqueuelen 10
>> ip -6 addr add fdd1:c52a:3c24:3384::1/64 dev "$INTERFACE
>> subnet-up:
>> #!/bin/sh
>> [ -z "$NAME" ] && exit 0
>> [ "$NAME" = "$NODE" ] && exit 0
>> logger -t tinc Adding route to $SUBNET for $NODE on $NAME
>> ip -6 route replace $SUBNET dev $INTERFACE
>> The VPN tun interfaces use private IPv6 IP addresses in the
>> fdd1:c52a:3c24:3384::/64 range.
>> I am then using the host entries at each site to advertise an IPv6
>> /64 subnet used internally (although still publically routable 
>> address
>> subnet) so that it is routed over the VPN tunnel to the other side.
>> 
>> This is working pretty well and I am getting around 80MBits/sec 
>> throughput.
>> However we have an cron process that runs every 1 minute and makes
>> several HTTP requests over the VPN every 10s.
>> About 10-12 times a day we are getting these errors after the
>> specified 5 second connect timeout set in the app.
>> Request failed: connect() timed out!
>> 
>> If we disable the VPN and just route the requests over the internet
>> (as I said they are publically routable addresses) then we do not see
>> these errors, suggesting this is not an application problem.
>> We are also running Cacti and Nagios over the VPN for monitoring the
>> remote site.
>> The traffic level is low, averaging about 20 kbps, but quiet bursty,
>> as every few minutes nagios/cacti runs, and the rest of the time the
>> tunnel is quiet except for this cron app that makes a very small HTTP
>> request every 10s.
>> 
>> Do you know what I could be looking at to fix this?
>> I have found these posts that suggest a similar connect() timeout 
>> issue:
>> Page 12 of this doc:
>> http://tinc-vpn.org/presentations/fosdem-2011/ec2_vpn_fosdem2011.pdf
>> http://thr3ads.net/tinc-devel/2010/10/1964008-Tweaks-for-high-bandwidth-tinc
>> I have tried disabled replay protection, setting IffOneQueue,
>> lowering and increasing the txqueuelen, setting priority of the tinc
>> process.
>> None of these settings have improved things though.
>> Any thoughts would be much appreciated.
>> Thanks
>> Tom