Linux/iptables

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Revision as of 18:26, 4 December 2023 by Marcluer (talk | contribs)
Tables Chains
FILTER
  • INPUT
  • FORWARD
  • OUTPUT
NAT
  • PREROUTING
  • OUTPUT
  • POSTROUTING
MANGLE

(modify ip headers)

  • PREROUTING
  • INPUT
  • FORWARD
  • OUTPUT
  • POSTROUTING
RAW

(connection tracking)

  • PREROUTING
  • OUTPUT
(SECURITY)

(SELinux)

  • INPUT
  • FORWARD
  • OUTPUT
Targets valid in note
REJECT INPUT, FORWARD, OUTPUT sends response back
DROP no response
ACCEPT
RETURN
MASQUERADE POSTROUTING
REDIRECT NAT:PREROUTING + NAT:OUTPUT

Basics

iptables
         -A (append - add rule at end)             -i (input interface)          -j (target)
         -C (check)                                -o (output interface)
         -D (delete - remove rule)                 -s (source address)    
         -F (flush - remove all rules)             -d (destination address)
         -I (insert - add at position)              
         -L (list - show all rules in chain)       -p      (protocol (tcp/udp))
         -N (new chain)                            --dport (port)
         -X (delete chain)

         -t (table to manipulate (default: filter)

         -n (numeric output of addresses and ports)

View state

iptables-save                  # show everything

iptables --list-rules          # list filter rules (default: filter)
iptables --list-rules -t nat   # list nat rules

raspi wifi to ethernet

  • rc.local
    • iptables --table nat --append POSTROUTING --out-interface wlan0 -j MASQUERADE
    • iptables --append FORWARD --in-interface eth0 -j ACCEPT

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