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# @summary This defined resource manages ferm/iptables chains
#
# @example create a custom chain, e.g. for all incoming SSH connections
# ferm::chain{'check-ssh':
# chain => 'SSH',
# disable_conntrack => true,
# log_dropped_packets => true,
# }
#
# @param disable_conntrack Disable/Enable usage of conntrack. By default, we enable conntrack only for the filter INPUT chain
# @param drop_invalid_packets_with_conntrack Enable/Disable the `mod conntrack ctstate INVALID DROP` statement. Only works if `$disable_conntrack` is `false` in this chain. You can set this to false if your policy is DROP.
# @param log_dropped_packets Enable/Disable logging of packets to the kernel log, if no explicit chain matched
# @param policy Set the default policy for CHAIN (works only for builtin chains)
# Allowed values: (ACCEPT|DROP) (see Ferm::Policies type)
# @param chain Name of the chain that should be managed
# Allowed values: String[1]
# @param table Select the target table (filter/raw/mangle/nat)
# Allowed values: (filter|raw|mangle|nat) (see Ferm::Tables type)
# @param ip_versions Set list of versions of ip we want ot use.
#
define ferm::chain (
Boolean $log_dropped_packets = false,
Boolean $drop_invalid_packets_with_conntrack = false,
Boolean $disable_conntrack = true,
String[1] $chain = $name,
Optional[Ferm::Policies] $policy = undef,
Ferm::Tables $table = 'filter',
Array[Enum['ip','ip6']] $ip_versions = $ferm::ip_versions,
) {
# prevent unmanaged files due to new naming schema
# keep the default "filter" chains in the original location
# only prefix chains in other tables with the table name
if $table == 'filter' and $chain in ['INPUT', 'FORWARD', 'OUTPUT'] {
$filename = "${ferm::configdirectory}/chains/${chain}.conf"
} else {
$filename = "${ferm::configdirectory}/chains/${table}-${chain}.conf"
}
$builtin_chains = {
'raw' => ['PREROUTING', 'OUTPUT'],
'nat' => ['PREROUTING', 'INPUT', 'OUTPUT', 'POSTROUTING'],
'mangle' => ['PREROUTING', 'INPUT', 'FORWARD', 'OUTPUT', 'POSTROUTING'],
'filter' => ['INPUT', 'FORWARD', 'OUTPUT'],
}
if $policy and ! ($chain in $builtin_chains[$table]) {
fail("Can only set a default policy for builtin chains. '${chain}' is not a builtin chain.")
}
# concat resource for the chain
concat{$filename:
ensure => 'present',
}
concat::fragment{"${table}-${chain}-policy":
target => $filename,
content => epp(
"${module_name}/ferm_chain_header.conf.epp", {
'policy' => $policy,
'disable_conntrack' => $disable_conntrack,
'drop_invalid_packets_with_conntrack' => $drop_invalid_packets_with_conntrack,
}
),
order => '01',
}
if $log_dropped_packets {
concat::fragment{"${table}-${chain}-footer":
target => $filename,
content => epp("${module_name}/ferm_chain_footer.conf.epp", { 'chain' => $chain }),
order => 'zzzzzzzzzzzzzzzzzzzzz',
}
}
# make sure the generated snippet is actually included
# the ordering here is hacked. We might end up with multiple blocks for the same filter+chain.
# This happens if we add ipset matches. We suffix this ordering with `bbb`. This allows us to
# insert ipset matches before other rules by adding `-aaa` or
# insert them at the end by ordering them with `-ccc`.
concat::fragment{"${table}-${chain}-config-include":
target => $ferm::configfile,
content => epp(
"${module_name}/ferm-table-chain-config-include.epp", {
'ip' => join($ip_versions, ' '),
'table' => $table,
'chain' => $chain,
'filename' => $filename,
}
),
order => "${table}-${chain}-bbb",
require => Concat[$filename],
}
}
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