Problems with Proxy ARP

Marcus Limosani
2011-01-09T15:59:03Z

I am not sure when it happened, but at some point, a ProxyARP''d server
I have running in my network is no longer visible either internally or
externally.

I am running Shorewall 4.4.9 on a Gentoo box.

The relelvant config files are as follows

INTERFACES file

#ZONE  INTERFACE          BROADCAST       OPTIONS
net     ppp0            -
dhcp,tcpflags,nosmurfs,routefilter,proxyarp,routeback,blacklist
loc     eth1            detect
tcpflags,nosmurfs,routefilter,proxyarp,routeback,blacklist


POLICIES
###############################################################################
#SOURCE                             DEST                      POLICY
LOG LEVEL           LIMIT:BURST

loc                          net                         ACCEPT
net                         all                            DROP
info
# THE FOLLOWING POLICY MUST BE LAST
all                            all                            REJECT
info

FIREWALL RULES - relevant to the ProxyArp''d address
# Hosting Box
ACCEPT:info       net         loc:203.36.xx.xxx              tcp
20,21,22,25,53,80,110,143,443,993,995
ACCEPT:info       net         loc:203.36.xx.xxx              udp        53
ACCEPT:info       net:202.124.xxx.xxx/29 loc:203.36.xx.xxx              tcp
ACCEPT:info       net:202.124.xxx.xxx/29 loc:203.36.xx.xxx              udp

ACCEPT:info       net         loc:203.36.75.210              tcp
20,21,22,25,53,80,110,143,443,993,995
ACCEPT:info       net         loc:203.36.75.210              udp        53

SHOREWALL CONF File
###############################################################################
#
# Shorewall version 4.0 - Sample shorewall.conf for two-interface
#                         configuration.
# Copyright (C) 2006,2007 by the Shorewall Team
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# See the file README.txt for further details.
#
# For information about the settings in this file, type "man
shorewall.conf"
#
# The manpage is also online at
# http://shorewall.net/manpages/shorewall.conf.html
#
###############################################################################
#                                    S T A R T U P   E N A B L E D
###############################################################################

STARTUP_ENABLED=Yes

###############################################################################
#                                           V E R B O S I T Y
###############################################################################

VERBOSITY=1

###############################################################################
#                              C O M P I L E R
#      (setting this to ''perl'' requires installation of
Shorewall-perl)
###############################################################################

SHOREWALL_COMPILER
###############################################################################
#                                                    L O G G I N G
###############################################################################

LOGFILE=/var/log/messages

STARTUP_LOG
LOG_VERBOSITY
LOGFORMAT="Shorewall:%s:%s:"

LOGTAGONLY=No

LOGRATE
LOGBURST
LOGALLNEW
BLACKLIST_LOGLEVEL
MACLIST_LOG_LEVEL=info

TCP_FLAGS_LOG_LEVEL=info

SMURF_LOG_LEVEL=info

LOG_MARTIANS=Yes

###############################################################################
#             L O C A T I O N      O F       F I L E S   A N D   D I R E C T O R
I E S
###############################################################################

IPTABLES
IP
TC
IPSET
PATH=/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/bin:/usr/local/sbin

SHOREWALL_SHELL=/bin/sh

SUBSYSLOCK
MODULESDIR
CONFIG_PATH=/etc/shorewall:/usr/share/shorewall

RESTOREFILE
IPSECFILE=zones

LOCKFILE
###############################################################################
#                             D E F A U L T   A C T I O N S / M A C R O S
###############################################################################

DROP_DEFAULT="Drop"
REJECT_DEFAULT="Reject"
ACCEPT_DEFAULT="none"
QUEUE_DEFAULT="none"
NFQUEUE_DEFAULT="none"

###############################################################################
#                        R S H / R C P  C O M M A N D S
###############################################################################

RSH_COMMAND=''ssh ${root}@${system} ${command}''
RCP_COMMAND=''scp ${files} ${root}@${system}:${destination}''

###############################################################################
#                                             F I R E W A L L       O P T I O N
S
###############################################################################

IP_FORWARDING=On
ADD_IP_ALIASES=Yes
ADD_SNAT_ALIASES=No
RETAIN_ALIASES=No
TC_ENABLED=Internal
TC_EXPERT=No
CLEAR_TC=Yes
MARK_IN_FORWARD_CHAIN=No
CLAMPMSS=Yes
ROUTE_FILTER=No
DETECT_DNAT_IPADDRS=No
MUTEX_TIMEOUT=60
ADMINISABSENTMINDED=Yes
BLACKLISTNEWONLY=Yes
DELAYBLACKLISTLOAD=No
MODULE_SUFFIXDISABLE_IPV6=No
BRIDGING=No
DYNAMIC_ZONES=No
PKTTYPE=Yes
NULL_ROUTE_RFC1918=No
MACLIST_TABLE=filter
MACLIST_TTLSAVE_IPSETS=No
MAPOLDACTIONS=No
FASTACCEPT=No
IMPLICIT_CONTINUE=No
HIGH_ROUTE_MARKS=No
USE_ACTIONS=Yes
OPTIMIZE=1
EXPORTPARAMS=No
EXPAND_POLICIES=Yes
KEEP_RT_TABLES=No
DELETE_THEN_ADD=Yes
MULTICAST=No
DONT_LOADAUTO_COMMENT=Yes
MANGLE_ENABLED=Yes
USE_DEFAULT_RT=No
RESTORE_DEFAULT_ROUTE=Yes
AUTOMAKE=No
WIDE_TC_MARKS=Yes

###############################################################################
#                                             P A C K E T   D I S P O S I T I O
N
###############################################################################

BLACKLIST_DISPOSITION=DROP
MACLIST_DISPOSITION=REJECT
TCP_FLAGS_DISPOSITION=DROP
#LAST LINE -- DO NOT REMOVE


I am loathe to upgrade for the sake of upgrading, as things have previously gone
wrong, and other than this (which is atm rather a big problem) everything else
is operating ok.

Hoping someone might see a hole in my config as to why the arp''d system
cannot reach the external network, or be reached.