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What does input J reject-with ICMP-host-prohibited iptables do?
What -A INPUT -j REJECT –reject-with icmp-host-prohibited Iptables line does exactly? The REJECT target rejects the packet. If you do not specify which ICMP message to reject with, the server by default will send back ICMP port unreachable (type 3, code 3).
When to use the option TCP-reset in TCP?
The option tcp-reset can be used on rules which only match the TCP protocol: this causes a TCP RST packet to be sent back. This is mainly useful for blocking ident (113/tcp) probes which frequently occur when sending mail to broken mail hosts (which won’t accept your mail otherwise).
Is there a way to reject an ICMP message?
The REJECT target rejects the packet. If you do not specify which ICMP message to reject with, the server by default will send back ICMP port unreachable (type 3, code 3). –reject-with modifies this behaviour to send a specific ICMP message back to the source host.
What does the ICMP host prohibited message mean?
The icmp-host-prohibited is just the reject message with whom the packet gets rejected. That means that your server will notify the sender that the packet was rejected with that message.
How to block ICMP ping request in iptables?
iptables -A OUTPUT -p icmp –icmp-type 8 -j DROP. ICMP echo-request type will be block by above rule. See ICMP TYPE NUMBERS (type fields). You can also get list of ICMP types, just type following command at shell prompt: # /sbin/iptables -p icmp -h.
Is the VM iptables OK for ICMP traffic?
Your VM’s iptables looks OK for ICMP traffic to go through, although you normally don’t need to set FORWARD’s policy to DROP unless you’ve enabled ip_forward. On the host… that depends on the setup. Thanks for contributing an answer to Unix & Linux Stack Exchange!
Where does reject rule end in sysconfig / iptables?
Then of course this will end up after the REJECT rule (because you told it to append the rule to the existing rulset). You have a few choices: You can simply edit /etc/sysconfig/iptables by hand, insert the rules you want, and run service iptables restart.
How does the-a command to iptables work?
The -A command to iptables simply “appends” a rule. So if you’re existing ruleset looks like this: Then of course this will end up after the REJECT rule (because you told it to append the rule to the existing rulset).