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Top Forums UNIX for Advanced & Expert Users Multi-table iptables Question Post 302911816 by knightfirefx on Sunday 3rd of August 2014 03:18:29 PM
Old 08-03-2014
Multi-table iptables Question

I have a question regarding IPTables packet flow, that I am hoping I can get an answer to.

We have a fairly advanced implementation of IPTables that I am trying to convert into a third party product and I am not quite certain on the packet flow in the current IPTables implementation.

We are using Mangle, NAT and Filter tables - and my question is this:

We have a PREROUTING chain defined in Mangle AND NAT tables. If a rule is matched with a -j of ACCEPT in the Mangle PREROUTING chain, does the packet still flow to the NAT PREROUTING chain? Or does it just go to the FORWARD chain and skip any other PREROUTING chains in other tables?

That is the missing piece of logic in my head and I would love to have that answered, thank you.
 

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upnpd.conf(5)							File Formats Manual						     upnpd.conf(5)

NAME
upnpd.conf - upnpd(8) configuration file SYNOPSIS
upnpd.conf DESCRIPTION
upnpd.conf contains the configuration details to do with run-time of upnpd(8). Configuration items related to starting the daemon such as interface names are defined, for Debian, in /etc/default/linux-igd. OPTIONS
iptables_location The full path and name of the iptables executable, (enclosed in quotes). Example: iptables_location = "/sbin/iptables" debug_mode Daemon debug level. Messages are logged via syslog to debug. 0 - no debug messages 1 - log errors 2 - log errors and basic info 3 - log errors and verbose info default = 0 Example: debug_mode = 2 create_forward_rules Should the daemon create rules in the forward chain, or not. This is necessary if your firewall has a drop or reject policy in your forward chain. allowed values: yes,no default = no Example: create_forward_rules = yes forward_rules_append Should the daemon insert or append rules in the forward chain. Normally you will want to insert rules at the beginning of the for- ward chain, so that they apply before any drop or reject rules later in the chain. This option only applies if "create_for- ward_rules = yes". As an experiment, this setting now also affects the PREROUTING chain in the same way. If this causes you problems please let me (Debian maintainer) know through the BTS. Tip: If you need to insert rules somewhere in the middle of the PREROUTING or FORWARD chains, instead of first or last, then you should create a new empty chain, e.g forwardUPnP, and set forward_chain_name to that chain. Then insert a rule to jump to for- wardUPnP in the appropriate place in the PREROUTING or FORWARD chain. (The value of forward_rules_append probably won't matter much in that case.) allowed values: yes,no default = no Example: forward_rules_append = no forward_chain_name The name of the chain to put the forward rules in. This option only applies if "create_forward_rules = yes". allowed values: a-z, A-Z, _, - default = FORWARD Example: forward_chain_name = FORWARD prerouting_chain_name The name of the chain to put prerouting rules in. allowed values: a-z, A-Z, _, - default = PREROUTING Example: prerouting_chain_name = PREROUTING upstream_bitrate The internet line upstream bit rate reported from the daemon. Value in bits per second. default = 0 Example: upstream_bitrate = 512000 downstream_bitrate The internet line downstream bit rate reported from the daemon. Value in bits per second. default = 0 Example: downstream_bitrate = 512000 duration The default duration of port mappings, used when the client doesn't specify a duration. Can have the following values: 0 - no default duration specified seconds | HH:MM - duration from the time of addition @seconds | @HH:MM - expire mapping at the specified time of day default = 0 Example: duration = 86400 # One day xml_document_path The path to the xml documents. Do not include the trailing "/". default = /etc/linuxigd Example: xml_document_path = /etc/linuxigd description_document_name The name of the igd device xml description document, underneath xml_document_path. default = gatedesc.xml Example: description_document_name = gatedesc.xml listenport The UPnP port to listen on. default = 0 (first free UPnP port, starting with 49152). Example: listenport = 0 paranoid Paranoid forwarding setting. Can have the following values: 0 - allow internal hosts to forward to any other (internal) host. 1- only allow internal hosts to forward to themselves. default = 0 Example: paranoid = 1 SEE ALSO
upnpd(8) AUTHOR
This manual page was written by Nick Leverton <nick@leverton.org> for the Debian GNU/Linux system (but may be used by others). May 4, 2008 upnpd.conf(5)
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