What is the use of mangle table in iptables?

The Mangle Table. The mangle table is used to alter the IP headers of the packet in various ways. For instance, you can adjust the TTL (Time to Live) value of a packet, either lengthening or shortening the number of valid network hops the packet can sustain.

What is mangle Prerouting?

mangle. PREROUTING. This chain is normally used for mangling packets, i.e., changing TOS and so on. This is also where the non-locally generated connection tracking takes place, which we discuss in the The state machine chapter.

What happens to packets with no match in a routing table?

Routers will look at the destination address on a packet, and try to find a match in its routing table. If it cannot find a match it will drop the packet and send an ICMP message to the source to tell it that is has no route to the destination network.

What is Prerouting and Postrouting in iptables?

PREROUTING: Immediately after being received by an interface. POSTROUTING: Right before leaving an interface. FORWARD: For any packets coming in one interface and leaving out another.

Should I use Nftables or iptables?

Nftables is easier to use and combines all tools of the IPtables framework (e. g. iptables, ip6tables, arptables, etc.) in a single tool. The syntax has also become better and easier, but there is a compatibility layer so you could still use the old IPtables syntax even if filtering is internally done with nftables.

Should I use Nftables?

Nftables as a packet filtering/classification framework for filtering network traffic is very stable at this point and addresses issues with IPTables. Nftables is generally regarded as being faster than IPTables, provide better rule-set handling, API benefits, more extensible, and other advantages.

What is NAT Prerouting?

PREROUTING: This chain is used to make any routing related decisions before (PRE) sending any packets. Always remember that in PREROUTING/POSTROUTING i.e. NAT table the ACCEPT/DROP/REJECT etc targets of the default FILTER table will not work. The NAT table is only used for taking routing decisions.

Is iptables outdated?

iptables has also been deprecated. The underlying netfilter has not been deprecated; the userspace application for managing it is just changing from the iptables (and ip6tables, ebtables, arptables, etc.) to nftables.

https://www.youtube.com/watch?v=jgH976ymdoQ