Quick HOWTO : Ch14 : Linux Firewalls Using iptables - Linux Home Networking - The Diigo Meta page

• 14 Aug 17
  

  vijayaprakash krishnan

  "ation of the TCP packet quality of service bits before routing occurs. (Rarely used in SOHO environments)"

  Networks

• 11 Sep 16
  

  szyszy

  iptables linux-vpn-setup

• 27 Aug 16
  

  Radoslaw Tomaszewski

  linux iptables network firewall

• 08 Jun 16
  

  nullimage

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• 14 Feb 16
  

  xinuya
• 11 Feb 16
  

  LeStef DuSud

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• 01 Oct 14
  

  Charlie Smith

  SU linux unix

• 20 Sep 13
  

  Justin Garrison

  network sysadmin linux iptables firewall security howto networking

• 09 Aug 13
  

  Hank Peng
  • a sequence of built-in tables (queues) for processing
  • mangle table
  • built-in chains
  • filter queue
  • Forward chain
  • Input chain
  • Output chain
  • nat queue
  • Pre-routing chain
  • destination address of the packet needs to be changed
  • source address of the packet needs to be changed
  • Post-routing chain
  • Network address translation for packets generated by the firewall
  • the chain for each firewall rule you create
  • specify the table
  • The filter table is therefore the default.
  • first examined by your rules in the mangle table's PREROUTING chain
  • inspected by the rules in the nat table's PREROUTING chain to see whether the packet requires DNAT
  • then routed
  • then it is filtered by the rules in the FORWARD chain of the filter table and
  • destined for a protected network
  • undergoes SNAT in the POSTROUTING chain before arriving at Network B
  • packet is destined for the firewall itself,
  • through the mangle table of the INPUT chain
  • he INPUT chain of the filter table before
  • reply is routed and inspected by the rules in the OUTPUT chain of the mangle table
  • OUTPUT chain of the nat table determine whether DNAT is required and the rules in the OUTPUT chain of the filter table are then inspected to help restrict unauthorized packets
  • iptables stops further processing.
  • packet is handed over to the end application or the operating system for processing
  • iptables stops further processing
  • packet is blocked
  • rewriting the destination IP address of the packet
  • rewriting the source IP address of the packet
  • do Source Network Address Translation.
  • By default the source IP address is the same as that used by the firewall's interface
  • filter, nat, mangle
  • specified target
  • Append rule to end of a chain
  • Flush. Deletes all the rules in the selected table

  37 more annotations...

• 04 Aug 13
  

  Murray Smithers

  Linux Networking Iptables

• 03 Apr 13
  

  Kemal Dogan

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• 05 Sep 12
  

  onyx peridot

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• 22 Aug 12
  

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• 25 Jun 12
  

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• 12 Jun 12
  

  Ernst Plüss

  "HTTP"

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• 31 May 12
  

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• 13 Apr 12
  

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• 29 Mar 12
  

  indreias

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• 12 Mar 12
  

  Jason Decker

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• 05 Mar 12
  

  man_os_3yr
• 17 Feb 12
  

  markus080402

  • One means of providing additional protection is to invest in a firewall. Though prices are always falling, in some cases you may be able to create a comparable unit using the Linux iptables package on an existing server for little or no additional expenditure. 
  • Filtering packets based on a MAC address and the values of the flags in the TCP header. This is helpful in preventing attacks using malformed packets and in restricting access from locally attached servers to other networks in spite of their IP addresses.
  • All packets inspected by iptables pass through a sequence of built-in tables (queues) for processing. Each of these queues is dedicated to a particular type of packet activity and is controlled by an associated packet transformation/filtering chain.

  • There are three tables in total. The first is the mangle table which is responsible for the alteration of quality of service bits in the TCP header. This is hardly used in a home or SOHO environment. 

    The second table is the filter queue which is responsible for packet filtering. It has three built-in chains in which you can place your firewall policy rules. These are the: 

     
    • Forward chain: Filters packets to servers protected by the firewall. 
    • Input chain: Filters packets destined for the firewall. 
    • Output chain: Filters packets originating from the firewall. 
     

    The third table is the nat queue which is responsible for network address translation. It has two built-in chains; these are: 

     
    • Pre-routing chain: NATs packets when the destination address of the packet needs to be changed. 
    • Post-routing chain: NATs packets when the source address of the packet needs to be changed

  2 more annotations...

• 16 Feb 12
  

  aborrell

  imported

• 09 Dec 11
  

  sebastos

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• 06 Dec 11
  

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• 24 Nov 11
  

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• 08 Nov 11
  

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  VPN VPS iptables firewall howto SNAT

• 19 Oct 11
  

  pdwhittaker

  Detailed introduction to iptables usage and operation, including masquerading.

  networking iptables reference system-administration Linux

• 11 Oct 11
  

  kwalleni

  "All packets inspected by iptables pass through a sequence of built-in tables (queues) for processing"

  IPTABLES

  • There are three tables in total.
  • All packets inspected by iptables pass through a sequence of built-in tables (queues) for processing

  • The second table is the filter queue which is responsible for packet filtering. It has three built-in chains in which you can place your firewall policy rules. These are the: 

     
    • Forward chain: Filters packets to servers protected by the firewall. 
    • Input chain: Filters packets destined for the firewall. 
    • Output chain: Filters packets originating from the firewall. 

  1 more annotation...

• 27 Sep 11
  

  Flash D

  linux security pre-diigo

• 28 Jul 11
  

  iptables linux firewall networking security

• 13 Jul 11
  

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• 24 Jun 11
  

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• 04 Jun 11
  

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• 29 May 11
  

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• 07 May 11
  

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• 06 May 11
  

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• 12 Apr 11
  

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• 19 Mar 11
  

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• 11 Mar 11
  

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• 03 Mar 11
  

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• 22 Feb 11
  

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• 03 Feb 11
  

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• 28 Dec 10
  

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• 22 Dec 10
  

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• 13 Dec 10
  

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• 01 Dec 10
  

  ankitmcgill

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  • The first is the mangle table which is responsible for the alteration of quality of service bits in the TCP header. This is hardly used in a home or SOHO environment.

  • The second table is the filter queue which is responsible for packet filtering. It has three built-in chains in which you can place your firewall policy rules. These are the: 

     
    • Forward chain: Filters packets to servers protected by the firewall. 
    • Input chain: Filters packets destined for the firewall. 
    • Output chain: Filters packets originating from the firewall.

  • The third table is the nat queue which is responsible for network address translation. It has two built-in chains; these are: 

     
    • Pre-routing chain: NATs packets when the destination address of the packet needs to be changed. 
    • Post-routing chain: NATs packets when the source address of the packet needs to be changed
  • You need to specify the table and the chain for each firewall rule you create. There is an exception: Most rules are related to filtering, so iptables assumes that any chain that's defined without an associated table will be a part of the filter table. The filter table is therefore the default.
  • -t <-table-> If you don't specify a table, then the filter table is assumed. As discussed before, the possible built-in tables include: filter, nat, mangle
  • -F Flush. Deletes all the rules in the selected table

  4 more annotations...

• 26 Nov 10
  

  Brian Beaver

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• 17 Nov 10
  

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• 11 Nov 10
  

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• 29 Oct 10
  

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  Must pay for specific examples of iptables scripts.

  linux firewall iptables security

• 27 Sep 10
  

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• 14 Sep 10
  

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• 14 Aug 10
  

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• 

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• 13 Aug 10
  

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• 10 Aug 10
  

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• 05 Aug 10
  

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• 05 Jul 10
  

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• 10 Jun 10
  

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• 05 May 10
  

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• 27 Apr 10
  

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• 31 Mar 10
  

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• 03 Mar 10
  

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• 25 Feb 10
  

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  linux iptables firewall sysadmin security delicious

• 22 Feb 10
  

  Nicolas Hennion

  Un très bon article sur IpTables

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• 12 Feb 10
  

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• 07 Feb 10
  

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• 01 Feb 10
  

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• 29 Jan 10
  

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• 25 Jan 10
  

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• 05 Jan 10
  

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  linux firewall iptables security howto sysadmin reference networking

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• 15 Dec 09
  

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• 07 Dec 09
  

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• 08 Nov 09
  

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• 02 Nov 09
  

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• 28 Oct 09
  

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• 25 Sep 09
  

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• 01 Sep 09
  

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• 29 Aug 09
  

  Tom Burley

  This looks like one of the best I've found

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• 28 Aug 09
  

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• 22 Aug 09
  

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• 14 Jul 09
  

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• 11 Jul 09
  

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• 22 Jun 09
  

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• 23 May 09
  

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• 22 May 09
  

  F C

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• 14 May 09
  

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• 11 May 09
  

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• 15 Apr 09
  

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• 05 Apr 09
  

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• 31 Mar 09
  

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• 27 Feb 09
  

  Padraig FitzGerald

  Creating an iptables firewall script requires many steps, but with the aid of the sample tutorials, you should be able to complete a configuration relatively quickly.
  
  

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• 24 Feb 09
  

  Jan Vereecken

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• 13 Feb 09
  

  Quick HOWTO : Ch14 : Linux Firewalls Using iptables - Linux Home Networking

• 07 Feb 09
  

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• 26 Jan 09
  

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