I need to change dst address in some outgoing connection originated from router itself (eg fetch command):
but it not working, any packets hitting this rule.
So my question is: for packets originated from router itself, NAT table (especially dstnat chain) is not processed?

Hi,

sry, but i do nat really understand what do u really want too.
Give us a liitle more information...

dstnat will not work for outgoing traffic.

dstnat will only transfer traffic, which comes in router to your destination ip, so this would not work for u.
try output instead of dstnat.

Thanks for explanation, looks like Mikrotik firewall is quiet different than Linux iptables where OUTPUT traffic passing through NAT table and changing dst ip address in packets generated on localhost is easy (ex. when ping 1.1.1.1 packets goes to 2.2.2.2). Another example, how force local traffic to pass through web proxy, in Mikrotik is not possible?