tcpcryptで動作するようにiptablesを設定する方法は？

バックグラウンド

OS：VirtualBoxで実行されているUbuntu 16.04 x64

私は最小限のUbuntu / Linuxの知識を持つ開発者であり、特定のエンドポイントと通信するときにtcpcryptを利用することを目標とするプロジェクトに割り当てられています。

tcpcryptには、encrpt / decryptのためにパケットをtcpcryptにルーティングするためにiptablesに必要なエントリを設定するシェルスクリプトが付属しています。このスクリプトの実行後、iptablesは次のようになります。

フィルタ

Chain INPUT (policy ACCEPT 4 packets, 552 bytes)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 ACCEPT     tcp  --  lo     any     anywhere             anywhere             tcp dpt:65530 tos match0x22/0xff
    0     0 NFQUEUE    tcp  --  any    any    !localhost            anywhere             tcp dpt:65530 flags:FIN,SYN,RST,PSH,ACK,URG/SYN NFQUEUE num 666
    0     0 NFQUEUE    tcp  --  any    any     anywhere             anywhere             multiport sports  !ssh,261,https,nntps,614,ldaps,684,695,ftps-data,ftps,telnets:pop3s tcp flags:FIN,SYN,RST,PSH,ACK,URG/SYN,ACK NFQUEUE num 666

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 4 packets, 536 bytes)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 NFQUEUE    tcp  --  any    any     anywhere             anywhere             multiport dports  !ssh,261,https,nntps,614,ldaps,684,695,ftps-data,ftps,telnets:pop3s tos match0x04/0xff owner UID match tcpcryptd NFQUEUE num 666
    0     0 NFQUEUE    tcp  --  any    any     anywhere             anywhere             tcp spt:65530 flags:FIN,SYN,RST,PSH,ACK,URG/SYN,ACK NFQUEUE num 666

nat

Chain PREROUTING (policy ACCEPT)
target     prot opt source               destination         
REDIRECT   tcp  --                                            multiport dports  !ssh,261,https,nntps,614,ldaps,684,695,ftps-data,ftps,telnets:pop3s redir ports 65530

Chain INPUT (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination         
ACCEPT     tcp  --  anywhere             anywhere             multiport dports  !ssh,261,https,nntps,614,ldaps,684,695,ftps-data,ftps,telnets:pop3s owner UID match tcpcryptd
REDIRECT   tcp  --  anywhere             anywhere             multiport dports  !ssh,261,https,nntps,614,ldaps,684,695,ftps-data,ftps,telnets:pop3s redir ports 65530

行方不明

Chain PREROUTING (policy ACCEPT)
target     prot opt source               destination         

Chain INPUT (policy ACCEPT)
target     prot opt source               destination         

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination         

Chain POSTROUTING (policy ACCEPT)
target     prot opt source               destination         
TOS        all  --  anywhere             anywhere             tos match0x04/0xff TOS and 0x00

これらのエントリを使用すると、すべてのパケットがキューに入れられ、tcpcryptがenc / decを選択します。

更新

これはiptablesのスクリプトです：

#!/bin/sh
#DAEMON_USER DIVERT_PORT ONLY_PORTS OMIT_PORTS

# determine which operation is requested (Append or Delete)
if [ "$1" = "start" -o -z "$1" ]; then
    # during startup, bail early if any of these commands fails
    set -e
    OP="-A"
elif [ "$1" = "stop" -o "$1" = "-f" ] ; then
    OP="-D"
else
    echo "Expected \"start\" or \"stop\" as first argument" >&2
    exit 1
fi

# determine which ports should be tcpcrypt-enabled
if [ -z "$ONLY_PORTS" -a -z "$OMIT_PORTS" ] ; then
    echo "Expected either OMIT_PORTS or ONLY_PORTS environment variables to be set" >&2
    exit 1
fi
if [ -n "$ONLY_PORTS" -a -n "$OMIT_PORTS" ] ; then
    echo "Expected only one of OMIT_PORTS or ONLY_PORTS environment variables to be set" >&2
    exit 1
fi
if [ -n "$OMIT_PORTS" ] ; then
    PORT_TEST=!
    PORTS="$OMIT_PORTS"
fi
if [ -n "$ONLY_PORTS" ] ; then
    PORT_TEST=
    PORTS="$ONLY_PORTS"
fi

# more necessary configuration
if [ -z "$DAEMON_USER" ] ; then
    echo "Expected DAEMON_USER environment variable to be set" >&2
    exit 1
fi
if [ -z "$DIVERT_PORT" ] ; then
    echo "Expected DIVERT_PORT environment variable to be set" >&2
    exit 1
fi

# some shorthand to make rules more concise
from_enabled_port="-m multiport $PORT_TEST --source-ports $PORTS"
to_enabled_port="-m multiport $PORT_TEST --destination-ports $PORTS"
NFQUEUE="NFQUEUE --queue-num $DIVERT_PORT"
CRYPT_PORT="65530"
REDIRECT="REDIRECT --to-port $CRYPT_PORT"
INJECT_TOS="0x22"
HANDSHAKE_TOS="0x04"

filter="$ECHO iptables -t filter $OP"

# Injection from daemon: Accept
$filter INPUT -i lo -p tcp --dport $CRYPT_PORT \
          -m tos --tos $INJECT_TOS \
  -j ACCEPT

# SYN redirected to daemon:
#   Queue for daemon to initiate proxy connection with original destination
$filter INPUT -p tcp --dport $CRYPT_PORT --tcp-flags ALL SYN \
  -j $NFQUEUE

# SYN+ACK on proxy connection:
#   Queue for daemon to complete original handshake
$filter INPUT -p tcp $from_enabled_port --tcp-flags ALL SYN,ACK \
  -j $NFQUEUE

# Handshake packet of proxy connection from daemon:
#   Queue for daemon to set tcp options via DIVERT_MODIFY
$filter OUTPUT -p tcp $to_enabled_port \
           -m tos --tos $HANDSHAKE_TOS \
           -m owner --uid-owner $DAEMON_USER \
  -j $NFQUEUE

# SYN+ACK on redirected connection:
#   Queue for daemon to delay handshake until proxy connection succeeds
$filter OUTPUT -p tcp --sport $CRYPT_PORT --tcp-flags ALL SYN,ACK \
  -j $NFQUEUE


nat="$ECHO iptables -t nat $OP"

# Inbound connection for enabled ports:
#   Redirect to daemon (at localhost:$CRYPT_PORT) for encryption
#
# (The nat module will now translate addresses in both directions,
#  for the lifetime of this connection.)
$nat PREROUTING -p tcp $to_enabled_port \
  -j $REDIRECT


# Proxy connection from daemon to enabled port: Accept
$nat OUTPUT -p tcp $to_enabled_port \
        -m owner --uid-owner $DAEMON_USER \
  -j ACCEPT

# Outbound connections to enabled ports on remote hosts:
#   Redirect to daemon (at localhost port $CRYPT_PORT) for encryption
#
# (The nat module will now translate addresses in both directions,
#  for the lifetime of this connection.)
$nat OUTPUT \! -o lo -p tcp $to_enabled_port \
  -j $REDIRECT


mangle="$ECHO iptables -t mangle $OP"

# Packets leaving the machine with bookkeeping mark: Remove mark
$mangle POSTROUTING -m tos --tos $HANDSHAKE_TOS \
  -j TOS --set-tos 0x00

質問

iptables次の制限を実現するには、現在の（上記を参照）エントリをどのように変更する必要がありますか。

1. 特定の宛先を持つパケットのみがtcpcryptのキューに入れられる必要があります。
2. 他のすべてのパケットはtcpcryptのキューに入れてはならず、自由に移動する必要があります。

私が試したこと

A）OUTPUT次のようなチェーンのtcp宛先に目的のIPアドレスを追加しようとしました：

Chain OUTPUT (policy ACCEPT 4 packets, 536 bytes)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 NFQUEUE    tcp  --  any    any     anywhere             XXX.XXX.XXX.XXX      multiport dports  !ssh,261,https,nntps,614,ldaps,684,695,ftps-data,ftps,telnets:pop3s tos match0x04/0xff owner UID match tcpcryptd NFQUEUE num 666
    0     0 NFQUEUE    tcp  --  any    any     anywhere             XXX.XXX.XXX.XXX      tcp spt:65530 flags:FIN,SYN,RST,PSH,ACK,URG/SYN,ACK NFQUEUE num 666

B）ソースパラメータと宛先パラメータをNATルールに追加しようとしました。

target     prot opt source               destination         
REDIRECT   tcp  --  XXX.XXX.XXX.XXX       XXX.XXX.XXX.XXX       multiport dports  !ssh,261,https,nntps,614,ldaps,684,695,ftps-data,ftps,telnets:pop3s redir ports 65530

ただし、宛先アドレスに関係なく、すべてのパケットはtcpcryptに送信されます。