Contents
What is an Iptable in Linux?
iptables is a user-space utility program that allows a system administrator to configure the IP packet filter rules of the Linux kernel firewall, implemented as different Netfilter modules. The filters are organized in different tables, which contain chains of rules for how to treat network traffic packets.
How do Linux bridges work?
A Linux bridge behaves like a network switch. It forwards packets between interfaces that are connected to it. It’s usually used for forwarding packets on routers, on gateways, or between VMs and network namespaces on a host. It also supports STP, VLAN filter, and multicast snooping.
How do I permanently add iptables in Linux?
Saving iptables firewall rules permanently on Linux
- Step 1 – Open the terminal.
- Step 2 – Save IPv4 and IPv6 Linux firewall rules.
- Step 3 – Restore IPv4 and IPv6 Linux filewall rules.
- Step 4 – Installing iptables-persistent package for Debian or Ubuntu Linux.
- Step 5 – Install iptables-services package for RHEL/CentOS.
How does iptable work with Linux bridge and brctl?
VM1 and 2 are on same subnet. Bridge has 2 interfaces added to brctl bridge. When I block VM2 ip using uptables -A FORWARD -s (VM1 ip) -j DENY it doesn’t work. I understand the packet never goes to network layer but this says “all iptables chains will be traversed while the IP packet is in the bridge code”.
What does iptables do for a Linux firewall?
Simply put, iptables is a firewall program for Linux. It will monitor traffic from and to your server using tables. These tables contain sets of rules, called chains, that will filter incoming and outgoing data packets.
How does the BR-NF code work in iptables?
The br-nf code makes bridged IP frames/packets go through the iptables chains. Ebtables filters on the Ethernet layer, while iptables only filters IP packets. Since the traffic you are working is ip, iptables rules still apply because of br-nf passing the bridged packets to iptables.
What is the difference between ebtables and iptables?
The br-nf code makes bridged IP frames/packets go through the iptables chains. Ebtables filters on the Ethernet layer, while iptables only filters IP packets. The explanations below will use the TCP/IP Network Model. It should be noted that the br-nf code sometimes violates the TCP/IP Network Model.