Hi,

I have successfully connected a network of about 60 nodes (many of which are 
virtual machines) with tinc 1.0 but encounter a severe bug when physical 
connectivity between two major locations is lost and then reconnected. From 
what I gathered, many nodes attempt to connect to many other nodes, causing 
100% CPU load on all nodes, taking down the whole network with no node 
succeeding connecting to any node. It seems unable to recover from this state. 
Luckily I can shutdown and restart most daemons with a few keystrokes, but I 
have to shutdown all, then start them sequentially and delayed or this "perfect 
storm" starts all over again.

The overall configuration is switch mode, with mixed IPv4 and IPv6 host 
addressing. Otherwise config is empty with these tweaks added to attempt 
mitigating the issue (with no success):

PingTimeout=15
UDPRcvBuf=8388608
UDPSndBuf=8388608
ProcessPriority=high

The daemon was upgraded to vanilla built 1.0.26 on all but two nodes before the 
most recent event. Host OS is Debian based, ranging from Squeeze to Jessie and 
few Ubuntu Trusty, with their respective stock kernels.

Also, I have tried firewalling the incoming UDP traffic on most nodes, forcing 
TCP for those connections, to narrow down the problem, but it doesn't seem to 
change anything.

At event time, the logs have these:
tincd[1093]: Flushing meta data to server1084 (x.x.x.x port y) failed: 
Connection reset by peer
tincd[1093]: Flushing meta data to server1070 (x.x.x.x port y) failed: 
Connection reset by peer
tincd[1093]: Flushing meta data to server1052 (x.x.x.x port y) failed: 
Connection reset by peer
tincd[1093]: Flushing meta data to server1071 (x.x.x.x port y) failed: 
Connection reset by peer

And these:
tincd[1093]: Metadata socket read error for server1076 (x:x:x:x:x:x:x:x port 
y): Connection reset by peer
tincd[1093]: Metadata socket read error for <unknown> (x.x.x.x port y): 
Connection reset by peer

And occasional:
tincd[8520]: Old connection_t for server1039 (x.x.x.x port y) status 0010 still 
lingering, deleting...

Any ideas?

Regards,

Pierre Beck
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