mjhjmtu

My OS is CentOS. Is it possible to disable/remove rules responsible for blocking packets?

Please note important thing: I would like to save redirecting rules (and also others). I would like to disable/remove only rules responsible for blocking/rejecting/flitering packets.

In other words, don't block anything.

This is a nuclear solution. It doesn't play nice with details. I advice you better first update your question with the output of:

iptables -L -nv

Especially if you're not sure what you want to keep. (And that's what you seem to be.) Anyway, in case something goes wrong, backup your tables:

iptables-save > iptables.bak

(To restore use iptables-restore iptables.bak.)

All the following commands require elevated privileges, so either execute them as root or use sudo. These steps are for IPv4 only.

• 
  

  set the default policy for the filter table to ACCEPT:

  
  
  

  iptables -P INPUT ACCEPT
  iptables -P OUTPUT ACCEPT
  

  
  


• 
  

  flush the filter table:

  
  
  

  iptables -F
  

  
  


• 
  

  zero the counters in the filter table (this one is optional):

  
  
  

  iptables -Z
  

  
  



• For a full clean-up, you might also have to remove custom chains. There's a nuke option here too, but it would remove all the custom chains in the table, while some might still be needed in the FORWARD chain. So these have to be cleaned up after careful inspection. But if they stay in the table with no rules directing to them, it's just plain definitions with no effect. Just space occupiers.