I have a remote server that I can access with SSH.

The first time, what I did was:

/usr/sbin/iptables -A INPUT -p tcp -s --dport 9043 -j ACCEPT
/usr/sbin/iptables -A INPUT -j DROP

Now I have only a single port accessible from a single IP and everything is locked.

How can I unblock all the traffic (at least for SSH)?

  • An iptables -F will flush everything. Then make sure you allow SSH access first. This assuming you still have console access to the machine itself. – Jeroen - IT Nerdbox Aug 8 '18 at 12:20
  • It would be easier to set your INPUT chain policy to drop. Allow then ssh traffic and that on 9043 No need for the -j DROP rule anymore – Valentin Bajrami Aug 8 '18 at 13:45

Assuming these are the only two rules you entered, if you want to have unrestricted access to all ports, just do:

# make default policy ACCEPT so that you don't block out yourself,
/usr/sbin/iptables -P INPUT ACCEPT
# remove all rules (flush)
/usr/sbin/iptables -F

make sure nothing else blocks you here (like default policy DROP for OUTPUT)

If you want to keep all others ports blocked, and just have ssh world-wide open, do this instead:

# insert new rule (in the beginning of the list) before that accepts ssh traffic 
/usr/sbin/iptables -A INPUT -p tcp --dport 9043 -j ACCEPT
# remove previously added rule (no longer needed)
/usr/sbin/iptables -D INPUT -p tcp -s --dport 9043 -j ACCEPT

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