Re: Clash Resolve Counter Increasing

[Tim Harman <tim@muppetz.com>]

> The same output a minute later:
> 
> tim@ferrari# sudo conntrack -S
> cpu=0           found=11150 invalid=48766 insert=0 insert_failed=1691 
> drop=1691 early_drop=0 error=1792 search_restart=0 clash_resolve=901897 
> chaintoolong=0
> cpu=1           found=10497 invalid=48631 insert=0 insert_failed=1748 
> drop=1748 early_drop=0 error=1422 search_restart=0 clash_resolve=907859 
> chaintoolong=0
> 
> So ~300 clash_resolve's a minute.
> 

Replying to myself, but documenting it for future reference in case 
anyone else stumbles on this.

My router has a DNS server on it.  Every query from a LAN client to the 
DNS server, even though it's the same subnet, created a conntrack entry. 
  I have a Zabbix server that generates A LOT of DNS queries, it was this 
Zabbix server and its huge amount of DNS queries causing the 
clash_resolve to kick in.

The fix has been to put in a conntrack ignore rule, so that queries to 
the DNS server from the local LAN aren't conntracked (They don't need to 
be).

This has

a) Removed a bunch of DNS conntrack entries I didn't need taking up 
conntrack space
b) Stopped clash_resolve from incrementing at all.

Hope this helps someone in the future.

Tim