Table of Contents

Primary Commands
Primary commands form groups of rules within a FireHOL firewall. The optional rule parameters given to the primary commands are indirectly applied to all sub-commands given within this primary command.

interface <real interface> <name> [optional rule parameters]

Description

The interface command creates a firewall for protecting the host the firewall is running, from the given interface.
The default interface policy is drop, so that if no subcommands are given, the firewall will just drop all incoming and outgoing traffic using this interface.

INPORTANT
Note that unlike ipchains, in iptables traffic passing through the firewall host (FORWARDed traffic) does not pass through the INPUT/OUTPUT chains of the firewall and therefore the interface rules in FireHOL never match it. To match the traffic passing through (even if DNATed) you have to place the filtering rules in router statements. Interface statements filter traffic only from/to the firewall host. Nothing else.

Parameters


router <name> [optional rule parameters]

Description

The router command creates a firewall for the traffic passing through the host running the firewall. The only acceptable policy on all router commands is return and therefore the policy subcommand cannot be used on routers. This means that no packets are dropped in a router. Packets not matched by any router command will be dropped at the end of the firewall.

INPORTANT
Note that unlike ipchains, in iptables traffic passing through the firewall host (FORWARDed traffic) does not pass through the INPUT/OUTPUT chains of the firewall and therefore the interface rules in FireHOL never match it. To match the traffic passing through (even if DNATed) you have to place the filtering rules in router statements. Interface statements filter traffic only from/to the firewall host. Router statements filter traffic that passes through the firewall host.

Parameters

Router statements produce similar iptables commands the interface statements produce. For each router statement an in_<name> and an out_<name> chain are produced to match the traffic in both directions of the router.
To match some client or server traffic the administrator has to specify the input/output interface or the source/destination of the request. All inface/outface, src/dst optional rule parameters can be given either on the router statement in which case will be applied to all subcommands for this router, or on each subcommand within a router. Both are valid.
For example:
		router mylan inface ppp+ outface eth0
			server http accept
			client smtp accept
	
The above says: Define a router that matches all requests that originate from some PPP interface and go out to eth0.
There is an HTTP server in eth0 that client from the PPP interfaces are allowed to reach.
Clients on eth0 are allowed to get SMTP traffic from the PPP interfaces.

While:
		router mylan
			server http accept inface ppp+ outface eth0
			server smtp accept inface eth0 outface ppp+
	
The above says: Define a router that matches any kind of forwarded traffic.
For HTTP traffic the clients are on a PPP interface and the servers on eth0.
For SMTP traffic the clients are on a eth0 interface and the servers o a PPP interface.

Please note that in the second example the SMTP traffic is matched again with a server subcommand, not a client (as in the first example).

The client subcommand reverses all the optional rules that are applied indirectly to it. Indirect rule parameters are those that are inherited from the parent command (router in this case).
To make it simple, for FireHOL a client is: "a server with all the implicit optional rule parameters reversed".

So, in the first example, the client simply flipped the inface and outface rules defined at the router and became an SMTP server.
In the second example there is nothing to be flipped, so server and client are exactly the same.

I suggest to use client subcommands in routers only if you have inface/outface or src/dst in the router statements. If you are building routers like the second example, don't use client, it is confusing.

Older versions of FireHOL did not allow server and client subcommands in routers. Only the route subcommand was allowed. Today, route is just an alias for server and can be used only in routers, not interfaces.

Any number of router statements can exist. Since the policy is RETURN on all of them, any traffic not matched by a router will continue to be checked against the second.

Sub-Commands
Subcommands must be given within Primary commands.

policy <action>

Description

The policy subcommand defines the default policy for an interface.

This directive accepts all the actions specified in Actions.

The policy of routers cannot be changed and is always RETURN.


protection [reverse] <type> [requests/sec [burst]]

Description

The protection subcommand sets a number of protection rules on an interface.

In router configurations, protections are setup on inface. The reverse keyword will make the protections setup on outface.

type can be:


server <service> <action> [optional rule parameters]

Description

The server subcommand defines a server of a service. For FireHOL a server is the destination of a request, and even if this is more complex for multi-socket services, for FireHOL a server always accepts requests.

The optional rule parameters given to the parent primary command (interface or router) are inherited by the server as they have been given.


This subcommand can be used on both interfaces and routers.

Parameters


client <service> <action> [optional rule parameters]

The client subcommand defines a client of a service. For FireHOL a client is the source of a request. FireHOL follows this simple rule even on multi-socket complex protocols, so that for FireHOL a client always sends requests.
The parameters are exactly the same with the server subcommand.

The optional rule parameters given to the parent primary command (interface or router) are inherited by the client, but they are reversed. For an explanation of this please refer to the documentation of the router primary command.


This subcommand can be used on both interfaces and routers.


route <service> <action> [optional rule parameters]

The route subcommand is an alias for the server command that can be used only on routers, not interfaces.

Helper Commands
Helper commands provide shortcuts for common functions not handled by the core of FireHOL's logic.

blacklist [option] <IPs>

The blacklist helper creates a blacklist for the IP addresses given. It supports two modes of operation based on the option given (or the absence of it).

The option can be:

The blacklist helper affects both interfaces and routers and can be used as many times as needed, but before the first interface statement. The blacklist helper accepts multiple IPs both as one quoted and space separated list and as separate arguments.

Example 1: blacklist this "195.97.5.202 10.1.1.1" # please note the quotes
Example 2: blacklist full 195.97.5.202 10.1.1.1 # please note the absence of quotes


dnat [to] <target> [optional rule parameters]

The dnat helper sets up a Destination NAT rule for routed traffic, by calling
nat to-destination <target> [optional rule parameters]

See the nat helper.

Example: dnat to 1.1.1.1 inface eth0 src 2.2.2.2 dst 3.3.3.3


iptables <arguments>

Description

The iptables command passes all its arguments to the real iptables command, during run-time.

You should not use in FireHOL configurations /sbin/iptables or other means to alter a FireHOL firewall. If you do, your commands will be run before FireHOL activates its firewall and while the previous firewall is still running. Also, since FireHOL will delete all previous firewall rules in order to activate the new firewall, any changes you will make, will be deleted too.

Always use the iptables directive to hook iptables commands in a FireHOL firewall. Nothing else.


mac <IP> <MAC>

The mac helper verifies that all traffic comming in with source the IP address, comes from the MAC address. The helper applies its rules to filter/INPUT and filter/FORWARD and checks the source IP address in combination with the source MAC address.

The same MAC address is allowed to use other IPs; only the specific IP is required to be used with the specified MAC address.

Packets with the given IP address but with wrong MAC address will be DROPped and a log (as in loglimit) with label "MAC MISSMATCH" will appear in the system logs.

This helper has to be used before all interface or router statements. Of course, you can use as many mac statements as you wish.

Example: mac 195.97.5.202 00:02:8a:21:a9:d8


mark <NUMBER> <WHERE> [optional rule parameters]

The mark helper marks the traffic with a specific mark NUMBER that can be matched by traffic shapping tools for controlling the traffic.

Parameters


Example 1: mark 1 OUTPUT, will mark with 1 all packets send by the local machine.
Example 2: mark 2 FORWARD, will mark with 2 all packets passing through the local machine.
Example 3: mark 3 FORWARD proto tcp dport 25 dst 1.1.1.1 src 2.2.2.2, will match with 3 all packets sent by 2.2.2.2, passing through the local machine and targeting port TCP/25 of host 1.1.1.1.


masquerade [reverse | interface] [optional rule parameters]

Masquerading is a special from of SNAT (Source NAT) that changes the source of requests when they go out and replaces their original source when replies come in. This way a Linux box can become an internet router for a LAN of clients having unroutable IP addresses. Masquerading takes care to re-map IP addresses and ports as required.

Masquerading is "expensive" compared to SNAT because it checks the IP address of the ougoing interface every time for every packet, and therefore it is suggested that if you connect to the internet with a static IP address, to prefer SNAT.

The masquerade helper sets up masquerading on the output of a network interface (not the interface command, but a real network interface).

If the masquerade command is placed within an interface command, its network interface(s) will be used.
If the masquerade command is placed within a router command that has an outface defined, then the outface network interface(s) will be used.
If placed within a router command but the keyword reverse is specified and the router command has an inface defined, then the inface network interface(s) will be used.
If placed outside and before all primary commands, an interface (or list of space separated interfaces, within double quotes) can be specified on the masquerade command.

In all cases, masquerade will setup itself on the output of the given interface(s).

Please note that if masquerade is used within some interface or router, it does not respect the optional rule parameters given to this interface or router command. Masquerade uses only its own optional rule parameters.

inface and outface should not be given as parameters to masquerade (inface because iptables does not support this in the POSTROUTING chain, and outface because it will be overwritten by the interface(s) mentioned above).

Finally, the masquerade helper will turn on FIREHOL_NAT and instruct the kernel to do packet forwarding (like the router commands do).

Example 1: before the first interface or router: masquerade eth0 src 10.0.0.0/8 dst not 10.0.0.0/8
Example 2: within an interface: masquerade, to masquerade on the output of this interface
Example 3: within a router: masquerade reverse, to masquerade on the output of the router's inface.


nat <type> <target> [optional rule parameters]

The nat helper sets up a NAT rule for routed traffic.

The type parameter can be:

Please understand that the optional rule parameters are used only to limit the traffic to be matched. Consider these examples:

CommandDescription
nat to-destination 1.1.1.1 Sends to 1.1.1.1 all traffic comming in or passing trhough the firewall host.
nat to-destination 1.1.1.1 dst 2.2.2.2 Redirects to 1.1.1.1 all traffic comming in or passing through, and going to 2.2.2.2.
nat to-destination 1.1.1.1 proto tcp dst 2.2.2.2 Redirects to 1.1.1.1 all TCP traffic comming in or passing through and going to 2.2.2.2.
nat to-destination 1.1.1.1 proto tcp dport 25 dst 2.2.2.2 Redirects to 1.1.1.1 all traffic comming in or passing through and going to 2.2.2.2 to port tcp/25.
nat to-destination 1.1.1.1 proto tcp dport 25 dst 2.2.2.2 src 3.3.3.3 Redirects to 1.1.1.1 all traffic comming in or passing through from 3.3.3.3 and going to 2.2.2.2 to port tcp/25.

Example 1: nat to-source 1.1.1.1 outface eth0 src 2.2.2.2 dst 3.3.3.3
Example 2: nat to-destination 4.4.4.4 inface eth0 src 5.5.5.5 dst 6.6.6.6
Example 3: nat redirect-to 8080 inface eth0 src 2.2.2.0/24 proto tcp dport 80


redirect [to] <target> [optional rule parameters]

The redirect helper catches all incomming traffic matching the optional rule parameters given and redirects it to ports on the local host, by calling
nat redirect-to <target> [optional rule parameters]

See the nat helper.

Example: redirect to 8080 inface eth0 src 2.2.2.0/24 proto tcp dport 80


snat [to] <target> [optional rule parameters]

The snat helper sets up a Source NAT rule for routed traffic, by calling
nat to-source <target> [optional rule parameters]

See the nat helper.

Example: snat to 1.1.1.1 outface eth0 src 2.2.2.2 dst 3.3.3.3


transparent_squid <port> <user> [optional rule parameters]

The transparent_squid helper sets up trasparent caching for HTTP traffic. The squid proxy is assumed to be running on the firewall host at port port (normally port is squid), with the credentials of the local user user (normally user is squid).

The transparent_squid helper can be used for two kinds of traffic:

Of course, make sure that your firewall allows requests to reach your proxy server.

Example 1: transparent_squid 3128 squid inface eth0 src 10.0.0.0/8
Example 2: transparent_squid 8080 "squid privoxy root bin" inface not "ppp+ ipsec+" dst not "a.not.proxied.server"


version <number>

Description

The version command states the FireHOL release the configuration file was created for. In case the configuration file is newer than FireHOL, FireHOL will deny to run it.

This command is here to allow you or anyone else design and distribute FireHOL configuration files, while ensuring that the correct FireHOL version is going to run them.

Since FireHOL configurations are BASH script, it is relatively easy to use FireHOL configurations as small scripts that dynamically process rules stored in a database, in a file system as separate files, or elsewhere. This directive will help the developers of FireHOL configurations to control the required version of FireHOL.

The FireHOL release is increased every time the format of the configuration file and the internals of FireHOL are changed.

Since FireHOL v1.67 version is not required to be present in every configuration file.

Actions
Actions are the actions to be taken on services and traffic described by other commands and functions. Please note that normally, FireHOL will pass-through to the generated iptables statements all the possible actions iptables accepts, but only the ones defined here can be used with lower case letters and currently it will be impossible to pass arguments to some unknown action. Also, keep in mind that the iptables action LOG is a FireHOL optional rule parameter (see log and loglimit) that can be defined together with one of the following actions and FireHOL will actually produce multiple iptables statements to achieve both the logging and the action.

accept

accept allows the traffic matching the rules to reach its destination.

Example: server smtp accept, to allow SMTP requests and their replies to flow.


reject [with message]

reject discards the matching traffic but sends a rejecting message back to the sender.

with is used to offer control on the message to be returned to the sender. with accepts all the arguments the --reject-with iptables expression accepts. For an updated list of these messages type iptables -j REJECT --help. Bellow you can find the list my system accepts.

By default (no with argument given), reject will send an icmp-port-unreachable on all protocols except TCP, for which it will send a tcp-reset.

MessageAliasDescriptionReference
icmp-net-unreachable net-unreach ICMP network unreachable

From RFC 1812 section 5.2.7.1
Generated by a router if a forwarding path (route) to the destination network is not available.

Notes
Use this with care. The sender and the routers between you and the sender may conclude that the whole network your host resides in, is unreachable and prevent other traffic from reaching you.

RFC 1812 RFC 792
icmp-host-unreachable host-unreach ICMP host unreachable

From RFC 1812 section 5.2.7.1
Generated by a router if a forwarding path (route) to the destination host on a directly connected network is not available (does not respond to ARP).

Notes
Use this with care. The sender and the routers between you and the sender may conclude that your server is unreachable and prevent the transmission of other traffic to you.

RFC 1812 RFC 792
icmp-proto-unreachable proto-unreach ICMP protocol unreachable

From RFC 1812 section 5.2.7.1
Generated if the transport protocol designated in a datagram is not supported in the transport layer of the final destination.

RFC 1812 RFC 792
icmp-port-unreachable port-unreach ICMP port unreachable (default)

From RFC 1812 section 5.2.7.1
Generated if the designated transport protocol (e.g. TCP, UDP, etc) is unable to demultiplex the datagram in the transport layer of the final destination but has no protocol mechanism to inform the sender.

In other words
Generated by hosts to indicate that the required port is not active.

RFC 1812 RFC 792
icmp-net-prohibited net-prohib ICMP communication with destination network administratively prohibited

From RFC 1812 section 5.2.7.1
This code was intended for use by end-to-end encryption devices used by U.S military agencies. Routers SHOULD use the newly defined Code 13 (Communication Administratively Prohibited) if they administratively filter packets.

In other words
Use it, but don't expect that this will be widely understood.

RFC 1812 RFC 1122
icmp-host-prohibited host-prohib ICMP communication with destination host administratively prohibited

From RFC 1812 section 5.2.7.1
This code was intended for use by end-to-end encryption devices used by U.S military agencies. Routers SHOULD use the newly defined Code 13 (Communication Administratively Prohibited) if they administratively filter packets.

In other words
Use it, but don't expect that this will be widely understood.

RFC 1812 RFC 1122
tcp-reset tcp-reset TCP RST

This is the port unreachable message of the TCP stack. It is useful when you want to prevent timeouts on rejected TCP services when the client is badly written to ignore ICMP port unreachable messages.

I suggest to use this for rejecting idents:
server ident reject with tcp-reset.

RFC 1122


Example 1: policy reject with host-unreach
Example 2: server ident reject with tcp-reset
Example 3: UNMATCHED_INPUT_POLICY="reject with host-prohib"


drop

drop silently discards the matching traffic. The fact that the traffic is silently discarded makes the sender timeout in order to conclude that it is not possible to use the wanted service.

Example: server smtp drop, to silently discard SMTP requests and their replies.


deny

deny is just an alias for drop, made for those who are used to ipchains terminology.

Example: server smtp deny, to silently discard SMTP requests and their replies.


return

return will return the flow of processing to the parent of the current command. Currently, it has meaning to specify the action return only as a policy to some interface.

Example: policy return, to have traffic not matched by any rule within an interface to continue traveling through the firewall and possibly matched by other interfaces bellow.


mirror

mirror will return the traffic to the wanted port, back to the sending host. Use this with care, and only if you understand what you doing. Keep also in mind that FireHOL will apply this action to both requests and replies comming in or passing through, and will replace it with REJECT for traffic generated by the local host.


redirect [to-port port]

redirect is used internally by FireHOL Helper Commands to redirect traffic to ports on the local host. Unless you are a developer, you will never need to use this directly.

Optional Rule Parameters
Optional rule parameters are accepted by many commands to narrow the match they do by default. The parameters described bellow are all that FireHOL supports. You should check the documentation of each command to find which parameters should not be used with it. Normally, all FireHOL commands are designed so that if you specify a parameters that is also used internally, the internal one will overwrite the one given in the configuration file. In such a case, FireHOL will present you a warning with the old and the new value.

Not all parameters should be used in all cases. For example sport and dport should not be used in normal server and client commands since such ports are internally defined by the services themselves. In any case, FireHOL will complain about optional rule parameters that should not be used in certain commands.

src [not] <host>

Description

src defines the source IP address of the REQUEST. If src is defined on a server statement it matches the source of the request which is the remote host, while if it is defined on a client statement it matches again the source of the request, but this time it is the local host. Focus on the REQUEST!!! Forget the reply.

Parameters


dst [not] <host>

Description

dst defines the destination of the REQUEST. If dst is defined on a server statement it matches the destination of the request which is the local host, while if it is defined on a client statement it matches again the destination of the request, but this time it is the remote host. Focus on the REQUEST!!! Forget the reply.

dst accepts the same parameters as src


inface [not] <interface>

Description

inface defines the interface the REQUEST is received via. inface cannot be used in interface commands.

Parameters


outface [not] <interface>

Description

outface defines the interface the REQUEST is send via. outface cannot be used in interface commands.

outface accepts the same parameters as inface.


custom "parameters"

Description

custom passes its arguments to the generated iptables commands.

It is required to quote all the parameters given to custom. If the parameters include a space character between some text that is required to be given to iptables as one argument, it is required to escape another set of quotes in order. Another way is to use double quotes externally and single quotes internally.

Example 1: server smtp accept custom "--some-iptables-option and_its_value"
Example 2: server smtp accept custom "--some-iptables-option 'one_value another_value'"


log "<some text>" [level a_level]

Description

log will log the matching packets to syslog. Note that this is not an action (in iptables it is). FireHOL will actually produce multiple iptables commands to accomplish both the action for the rule and the logging. You can control how logging works, by altering the variables FIREHOL_LOG_OPTIONS and FIREHOL_LOG_LEVEL. You can also change the level of just one rule by using the level argument of the log parameter.

FireHOL logs traffic, exactly the same way iptables does. Many users have complained about packet logs appearing at their console. To avoid this you will have to:

Actually klogd's -c option and iptables' --log-level option are the same thing (iptables accepts also the numeric values klogd accepts). If iptables logs at a higher priority than klogd is configured to use, then your packets will appear in the console too.

In most kernels klogd is by default configured to log everything, so if you don't also change klogd's -c option, the --log-level setting of iptables has no effect. Use the table bellow to match klogd options with --log-level options:

PriorityklogdiptablesDescription
0 0 emerg system is unusable
1 1 alert action must be taken immediately
2 2 crit critical conditions
3 3 error error conditions
4 4 warning (default) warning conditions
5 5 notice normal but significant condition
6 6 info informational
7 7 (default) debug debug-level messages

To prevent packet logs appearing to the console, klogd option must be LOWER than the one iptables uses.

On RedHat systems, you can configure klogd by changing /etc/sysconfig/syslog and adding to KLOGD_OPTIONS the required -c level.


loglimit "<some text>"

Description

loglimit is the same with log but limits the frequency of logging according to the setting of FIREHOL_LOG_FREQUENCY and FIREHOL_LOG_BURST.


proto [not] <protocol>

Description

proto sets the required protocol for the traffic. This command accepts anything iptables accepts as protocols.


limit <frequency> <burst>

Description

limit will limit the match in both directions of the traffic (request and reply). This is used internally by FireHOL and its effects has not been tested in the high level configuration file directives.


sport <port>

Description

sport defines the source port of a request. It accepts port names, port numbers, port ranges (FROM:TO) and multiple ports (or ranges) seperated by spaces and quoted as a single argument. This parameter should not be used in normal services definitions (client and server commands) or interface and router definitions, unless you really understand what you are doing.


dport <port>

Description

dport defines the destination port of a request. It accepts port names, port numbers, port ranges (FROM:TO) and multiple ports (or ranges) seperated by spaces and quoted as a single argument. This parameter should not be used in normal services definitions (client and server commands) or interface and router definitions, unless you really understand what you are doing.


uid [not] <user>

user [not] <user>

Description

uid or user define the operating system user sending this traffic. The parameter can be a username, a user number or a list of these two, seperated by spaces and quoted as a single argument.

This parameter can be used only in services (client and server commands) defined within interfaces, not routers. FireHOL is "smart" enough to apply this parameter only to traffic send by the localhost, i.e. the replies of servers and requests of clients. It is not possible, and FireHOL will simply ignore this parameter, on traffic coming in or passign through the firewall host.


Example 1: client "pop3 imap" accept user not "user1 user2 user3" dst mymailer.example.com
The above will allow local users except user1, user2 and user3 to use POP3 and IMAP services on mymailer.example.com. You can use this, for example, to allow only a few of the local users use the fetchmail program to fetch their mail from the mail server.


Example 2: server http accept user apache
The above will allow all HTTP to reach the local http server, but only if the web server is running as user apache the replies will be send back to the HTTP client.


gid <group>

group <group>

Description

gid or group define the operating system user group sending this traffic. The parameter can be a group name, a group number or a list of these two, seperated by spaces and quoted as a single argument.

This parameter can be used only in services (client and server commands) defined within interfaces, not routers. FireHOL is "smart" enough to apply this parameter only to traffic send by the localhost, i.e. the replies of servers and requests of clients. It is not possible, and FireHOL will simply ignore this parameter, on traffic coming in or passign through the firewall host.


pid <process>

process <process>

Description

pid or process define the operating system process ID (or PID) sending this traffic. The parameter can be a PID or a list of PIDs, seperated by spaces and quoted as a single argument.

This parameter can be used only in services (client and server commands) defined within interfaces, not routers. FireHOL is "smart" enough to apply this parameter only to traffic send by the localhost, i.e. the replies of servers and requests of clients. It is not possible, and FireHOL will simply ignore this parameter, on traffic coming in or passign through the firewall host.


sid <session>

session <session>

Description

sid or session define the operating system session ID of the process sending this traffic (The session ID of a process is the process group ID of the session leader). The parameter can be a list of such IDs, seperated by spaces and quoted as a single argument.

This parameter can be used only in services (client and server commands) defined within interfaces, not routers. FireHOL is "smart" enough to apply this parameter only to traffic send by the localhost, i.e. the replies of servers and requests of clients. It is not possible, and FireHOL will simply ignore this parameter, on traffic coming in or passign through the firewall host.


cmd <name>

command <name>

Description

cmd or command define the operating system command name of the process sending this traffic. The parameter can be a list of such command names, seperated by spaces and quoted as a single argument.

This parameter can be used only in services (client and server commands) defined within interfaces, not routers. FireHOL is "smart" enough to apply this parameter only to traffic send by the localhost, i.e. the replies of servers and requests of clients. It is not possible, and FireHOL will simply ignore this parameter, on traffic coming in or passign through the firewall host.

Variables that control FireHOL

DEFAULT_INTERFACE_POLICY

Description

DEFAULT_INTERFACE_POLICY controls the default action to be taken on traffic not matched by any rule within an interface. Actually, this is a global setting for what policy does for an interface.

All packets that reach the end of an interface are logged only if the action is not return or accept. You can control the frequency of this logging by altering the frequency loglimit uses.

Default: DEFAULT_INTERFACE_POLICY="DROP"

Example: DEFAULT_INTERFACE_POLICY="REJECT"


UNMATCHED_INPUT_POLICY

UNMATCHED_OUTPUT_POLICY

UNMATCHED_FORWARD_POLICY

Description

UNMATCHED_INPUT_POLICY controls the default action to be taken for incoming traffic not matched by any interface command.
UNMATCHED_OUTPUT_POLICY controls the default action to be taken for outgoing traffic not matched by any interface command.
UNMATCHED_FORWARD_POLICY controls the default action to be taken for forwarded traffic not matched by any router command.

All variables accept all the Actions FireHOL supports.

All packets that reach the end of firewall in all three chains are logged (always, regardless of these settings). You can control the frequency of this logging by altering the frequency loglimit uses.

Default: UNMATCHED_INPUT_POLICY="DROP"
Default: UNMATCHED_OUTPUT_POLICY="DROP"
Default: UNMATCHED_FORWARD_POLICY="DROP"

Example: UNMATCHED_INPUT_POLICY="REJECT"
Example: UNMATCHED_OUTPUT_POLICY="REJECT"
Example: UNMATCHED_FORWARD_POLICY="REJECT"


FIREHOL_INPUT_ACTIVATION_POLICY

FIREHOL_OUTPUT_ACTIVATION_POLICY

FIREHOL_FORWARD_ACTIVATION_POLICY

Description

All these variables have been added in v1.133

FIREHOL_INPUT_ACTIVATION_POLICY controls the default action to be taken for incoming traffic during firewall activation.
FIREHOL_OUTPUT_ACTIVATION_POLICY controls the default action to be taken for outgoing traffic during firewall activation.
FIREHOL_FORWARD_ACTIVATION_POLICY controls the default action to be taken for forwarded traffic during firewall activation.

All variables accept either ACCEPT, DROP or REJECT.

The default is ACCEPT in order to prevent a denial of service during a firewall restart. This is by design correct, since FireHOL will block all invalid connections after the firewall is fully activated (remember that FireHOL allows specific traffic to pass in both directions of the firewall).

Default: FIREHOL_INPUT_ACTIVATION_POLICY="ACCEPT"
Default: FIREHOL_OUTPUT_ACTIVATION_POLICY="ACCEPT"
Default: FIREHOL_FORWARD_ACTIVATION_POLICY="ACCEPT"

Example: FIREHOL_INPUT_ACTIVATION_POLICY="REJECT"
Example: FIREHOL_OUTPUT_ACTIVATION_POLICY="REJECT"
Example: FIREHOL_FORWARD_ACTIVATION_POLICY="REJECT"


FIREHOL_LOG_LEVEL

FIREHOL_LOG_OPTIONS

FIREHOL_LOG_FREQUENCY

FIREHOL_LOG_BURST

Description

FIREHOL_LOG_LEVEL controls the level at which iptables will log things to the syslog. For a description of the possible values supported and for per-rule control of log level, see the log optional rule parameter.

FIREHOL_LOG_OPTIONS controls the way iptables will log things to the syslog. The value of this variable is passed as is to iptables, so use exact iptables parameters.

FIREHOL_LOG_FREQUENCY and FIREHOL_LOG_BURST (added in v1.39 of FireHOL) control the frequency at each each logging rule will write packets to the syslog. FIREHOL_LOG_FREQUENCY is set to the maximum average frequency and FIREHOL_LOG_BURST specifies the maximum initial number of packets to match.

Default: FIREHOL_LOG_OPTIONS="--log-level warning"
Default: FIREHOL_LOG_FREQUENCY="1/second"
Default: FIREHOL_LOG_BURST="5"

Example: FIREHOL_LOG_OPTIONS="--log-level info --log-tcp-options --log-ip-options"
Example: FIREHOL_LOG_FREQUENCY="30/minute"
Example: FIREHOL_LOG_BURST="2"

To see the available iptables log options, run /sbin/iptables -j LOG --help
To see what iptables accepts as frequencies and bursts run, /sbin/iptables -m limit --help
You can also check man iptables.


DEFAULT_CLIENT_PORTS

Description

DEFAULT_CLIENT_PORTS controls the port range to be used when a remote client is specified. For localhost clients, FireHOL finds the exact client ports by querying the kernel options.

Default: DEFAULT_CLIENT_PORTS="1024:65535"
Example: DEFAULT_CLIENT_PORTS="0:65535"


FIREHOL_NAT

Description

If FIREHOL_NAT is set to 1, FireHOL will load NAT kernel modules for those services that they are require such. FireHOL sets this to 1 automatically if you use the Helper Commands that do NAT.

Default: FIREHOL_NAT="0"
Example: FIREHOL_NAT="1"


FIREHOL_AUTOSAVE

Description

FIREHOL_AUTOSAVE controls the file that will be created when FireHOL is called with the save command line argument. If this variable is empty (the default), FireHOL will try to detect where to save the file. Currently, the RedHat way (/etc/sysconfig/iptables) and the Debian way (/var/lib/iptables/autosave) are automatically detected (in the order given here) based on the existance of the directory this file should be created in.

Default: FIREHOL_AUTOSAVE=""
Example: FIREHOL_AUTOSAVE="/tmp/firehol-saved.txt"


FIREHOL_LOAD_KERNEL_MODULES

Description

FIREHOL_LOAD_KERNEL_MODULES controls the way FireHOL handles required kernel modules. If set to 0 (zero), FireHOL will not attempt to load kernel modules at all. Set this to 0 (zero) if you have compiled a kernel that has all the modules build into it.

Default: FIREHOL_LOAD_KERNEL_MODULES=1
Example: FIREHOL_LOAD_KERNEL_MODULES=0

Variables that FireHOL offers

RESERVED_IPS

Description

This variable includes all the IP addresses defined as IANA - Reserved by IANA. The supplied get-iana.sh script creates this variable by directly fetching this document.

Example: interface eth0 internet src not "${RESERVED_IPS}"


PRIVATE_IPS

Description

This variable includes all the IP addresses defined as Private or Test by RFC 3330.

Example: interface eth0 internet src not "${PRIVATE_IPS}"


UNROUTABLE_IPS

Description

This variable is both RESERVED_IPS and PRIVATE_IPS together. I suggest to use this variable on interfaces and routers accepting Internet traffic.

Example: interface eth0 internet src not "${UNROUTABLE_IPS}"


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FireHOL, a firewall for humans...
© Copyright 2003 Costa Tsaousis <costa@tsaousis.gr>