FTP Server

[Sven]

Hi!
Ich habe mir ProFTP eingerichtet und der läuft im Intranet ohne Probs. Nun möchte ich aber, daß ich auch vom Internet draufzugreifen kann. Wer kann mir die genauen Regeln sagen, die ich zum Forwarding brauche?
Habe SuSE 7.3 also IPTABLES.
Was muß ich jetzt genau einstellen?
Wenn möglich, die Änderungen im SuSE Firewall-Script posten.
Ich hoffe, ich habe mich verständlich ausgedrückt.
Danke

[gewitter]

sitzt der ftp-server nicht auf dem router, bzw hat der ftp-server "nur" eine lokale IP? wenn ja, kannst du das vergessen. woher soll der router wissen, welche anfragen von ausserhalb er an welche ip innerhalb weiterleiten soll? ansonsten brauchst du nur den port 21 freigeben und gar nichts forwarden.

[Descartes]

> ansonsten brauchst du nur den port 21 freigeben
FTP benötigt zwei (!) Ports: 20/tcp und 21/tcp

[gewitter]

und wofür braucht man port 20? erklär den leuten dann bitte auch, wann der benutzt wird.

[Johannes Hoen]

Also :

1. Man kann ports durchrouten , geht mit ipmasqadm und bei iptables per se
2. ftp besteht aus 2 kanälen. Einer für die Daten und einer zur Verbindungskontrolle. Am besten im RFC nachlesen oder im aktuellen Linux-magazin <img src="http://www.pl-forum.de/UltraBoard/Images/Happy.gif" border="0" align="middle">

[Descartes]

Auszug aus dem aktuellen Linux-Magazin ("Protokoll-Oldie: FTP stellt Firewalls vor Probleme"):

[...]
Ein FTP-Client sendet seine Kommandos über einen Kontrollkanal (Port 21/tcp) an den Server. Sobald eine Datei übertragen oder ein Directory-Listing zurückgegeben werden soll, ist aber eine zweite Verbindung erforderlich, der Datenkanal (Port 20/tcp). Über ihn laufen dann die eigentlichen Daten, die Steuerinformationen laufen weiterhin über den Kommandokanal.
[...]

RFC 2773 (Februar 2000) **letzte Erweiterung**
RFC 959 (Oktober 1985) **aktuelle Fassung**
RFC 114 (April 1971) **erster Vorläufer**

[gewitter]

port 20 wird von aussen geöffnet?!

[Sven]

Ich hab ProFTP auf meinem Server. Ansprechen will ich den FTP mit der IP, die der Server automatisch vom ISP zugeteilt bekommt. Soweit so gut, nur ich kann nicht auf den FTP connecten. Folgendes ist in der /var/log/messages zu finden:

May 9 19:59:24 server kernel: SuSE-FW-ACCESS_DENIED_FOR_INTIN=eth0 OUT= MAC=00:e0:7d:97:ac:03:00:e0:7d:94:fb:b6:08:00 SRC=192.168.1.10 DST=xxx.xxx.xxx.xxx LEN=48 TOS=0x00 PREC=0x00 TTL=128 ID=47109 DF PROTO=TCP SPT=2915 DPT=21 WINDOW=16384 RES=0x00 SYN URGP=0 OPT (020405B401010101)

Das ist mein Firewall-Script:
# 1.)
# Should the Firewall be started?
#
# This setting is done in /etc/rc.config (START_FW2="yes")

#
# 2.)
# Which is the interface that points to the internet/untrusted networks?
#
# Enter all the network devices here which are untrusted.
#
# Choice: any number of devices, seperated by a space
# e.g. "eth0", "ippp0 ippp1 eth0:1"
#
FW_DEV_EXT="ppp0"

#
# 3.)
# Which is the interface that points to the internal network?
#
# Enter all the network devices here which are trusted.
# If you are not connected to a trusted network (e.g. you have just a
# dialup) leave this empty.
#
# Choice: leave empty or any number of devices, seperated by a space
# e.g. "tr0", "eth0 eth1 eth1:1" or ""
#
FW_DEV_INT="eth0 eth0:0"

#
# 4.)
# Which is the interface that points to the dmz or dialup network?
#
# Enter all the network devices here which point to the dmz/dialups.
# A "dmz" is a special, seperated network, which is only connected to the
# firewall, and should be reachable from the internet to provide services,
# e.g. WWW, Mail, etc. and hence are at risk from attacks.
# See /usr/share/doc/packages/SuSEfirewall2/EXAMPLES for an example.
#
# Special note: You have to configure FW_FORWARD to define the services
# which should be available to the internet and set FW_ROUTE to yes.
#
# Choice: leave empty or any number of devices, seperated by a space
# e.g. "tr0", "eth0 eth1 eth1:1" or ""
#
FW_DEV_DMZ=""

#
# 5.)
# Should routing between the internet, dmz and internal network be activated?
# REQUIRES: FW_DEV_INT or FW_DEV_DMZ
#
# You need only set this to yes, if you either want to masquerade internal
# machines or allow access to the dmz (or internal machines, but this is not
# a good idea). This option supersedes IP_FORWARD from /etc/rc.config!
#
# Setting this option one alone doesn't do anything. Either activate
# massquerading with FW_MASQUERADE below if you want to masquerade your
# internal network to the internet, or configure FW_FORWARD to define
# what is allowed to be forwarded!
#
# Choice: "yes" or "no", defaults to "no"
#
FW_ROUTE="yes"

#
# 6.)
# Do you want to masquerade internal networks to the outside?
# REQUIRES: FW_DEV_INT or FW_DEV_DMZ, FW_ROUTE
#
# "Masquerading" means that all your internal machines which use services on
# the internet seem to come from your firewall.
# Please note that it is more secure to communicate via proxies to the
# internet than masquerading. This option is required for FW_MASQ_NETS and
# FW_FORWARD_MASQ.
#
# Choice: "yes" or "no", defaults to "no"
#
FW_MASQUERADE="yes"
#
# You must also define on which interface(s) to masquerade on. This is
# normally your external device(s) to the internet.
# Most users can leave the default below.
#
# e.g. "ippp0" or "$FW_DEV_EXT"
FW_MASQ_DEV="$FW_DEV_EXT"
#
# Which internal computers/networks are allowed to access the internet
# directly (not via proxys on the firewall)?
# Only these networks will be allowed access and will be masqueraded!
#
# Choice: leave empty or any number of hosts/networks seperated by a space.
# Every host/network may get a list of allowed services, otherwise everything
# is allowed. A target network, protocol and service is appended by a comma to
# the host/network. e.g. "10.0.0.0/8" allows the whole 10.0.0.0 network with
# unrestricted access. "10.0.1.0/24,0/0,tcp,80 10.0.1.0/24,0/0tcp,21" allows
# the 10.0.1.0 network to use www/ftp to the internet.
# "10.0.1.0/24,tcp,1024:65535 10.0.2.0/24" is OK too.
# Set this variable to "0/0" to allow unrestricted access to the internet.
#
FW_MASQ_NETS="192.168.1.0/24"

#
# 7.)
# Do you want to protect the firewall from the internal network?
# REQUIRES: FW_DEV_INT
#
# If you set this to "yes", internal machines may only access services on
# the machine you explicitly allow. They will be also affected from the
# FW_AUTOPROTECT_SERVICES option.
# If you set this to "no", any user can connect (and attack) any service on
# the firewall.
#
# Choice: "yes" or "no", defaults to "yes"
#
# "yes" is a good choice
FW_PROTECT_FROM_INTERNAL="no"

#
# 8.)
# Do you want to autoprotect all running network services on the firewall?
#
# If set to "yes", all network access to services TCP and UDP on this machine
# will be prevented (except to those which you explicitly allow, see below:
# FW_SERVICES_{EXT,DMZ,INT}_{TCP,UDP})
#
# Choice: "yes" or "no", defaults to "yes"
#
FW_AUTOPROTECT_SERVICES="yes"

#
# 9.)
# Which services ON THE FIREWALL should be accessible from either the internet
# (or other untrusted networks), the dmz or internal (trusted networks)?
# (see no.13 & 14 if you want to route traffic through the firewall) XXX
#
# Enter all ports or known portnames below, seperated by a space.
# TCP services (e.g. SMTP, WWW) must be set in FW_SERVICES_*_TCP, and
# UDP services (e.g. syslog) must be set in FW_SERVICES_*_UDP.
# e.g. if a webserver on the firewall should be accessible from the internet:
# FW_SERVICES_EXT_TCP="www"
# e.g. if the firewall should receive syslog messages from the dmz:
# FW_SERVICES_DMZ_UDP="syslog"
# For IP protocols (like GRE for PPTP, or OSPF for routing) you need to set
# FW_SERVICES_*_IP with the protocol name or number (see /etc/protocols)
#
# Choice: leave empty or any number of ports, known portnames (from
# /etc/services) and port ranges seperated by a space. Port ranges are
# written like this: allow port 1 to 10 -> "1:10"
# e.g. "", "smtp", "123 514", "3200:3299", "ftp 22 telnet 512:514"
# For FW_SERVICES_*_IP enter the protocol name (like "igmp") or number ("2")
#
# Common: smtp domain
FW_SERVICES_EXT_TCP="ftp ftp-data"
# Common: domain
FW_SERVICES_EXT_UDP="ftp-data" # Common: domain
# For VPN/Routing which END at the firewall!!
FW_SERVICES_EXT_IP=""
#
# Common: smtp domain
FW_SERVICES_DMZ_TCP=""
# Common: domain
FW_SERVICES_DMZ_UDP=""
# For VPN/Routing which END at the firewall!!
FW_SERVICES_DMZ_IP=""
#
# Common: ssh smtp domain
FW_SERVICES_INT_TCP="ssh smtp domain telnet 53 139 ftp 3128 110"
# Common: domain syslog
FW_SERVICES_INT_UDP="domain 53"
# For VPN/Routing which END at the firewall!!
FW_SERVICES_INT_IP=""

#
# 10.)
# Which services should be accessible from trusted hosts/nets?
#
# Define trusted hosts/networks (doesnt matter if they are internal or
# external) and the TCP and/or UDP services they are allowed to use.
#
# Choice: leave FW_TRUSTED_NETS empty or any number of computers and/or
# networks, seperated by a space. e.g. "172.20.1.1 172.20.0.0/16"
# Optional, enter a protocol after a comman, e.g. "1.1.1.1,icmp"
# Optional, enter a port after a protocol, e.g. "2.2.2.2,tcp,22"
#
FW_TRUSTED_NETS=""
FW_SERVICES_TRUSTED_TCP=""
FW_SERVICES_TRUSTED_UDP=""
FW_SERVICES_TRUSTED_IP=""
#
# 11.)
# How is access allowed to high (unpriviliged [above 1023]) ports?
#
# You may either allow everyone from anyport access to your highports ("yes"),
# disallow anyone ("no"), anyone who comes from a defined port (portnumber or
# known portname) [note that this is easy to circumvent!], or just your
# defined nameservers ("DNS").
# Note that if you want to use normal (active) ftp, you have to set the TCP
# option to ftp-data. If you use passive ftp, you don't need that.
# Note that you can't use rpc requests (e.g. rpcinfo, showmount) as root
# from a firewall using this script (well, you can if you include range
# 600:1023 in FW_SERVICES_EXT_UDP ...).
#
# Choice: "yes", "no", "DNS", portnumber or known portname, defaults to "no"
# if not set
#
# Common: "ftp-data", better is "yes" to be sure that everything else works <img src="http://www.pl-forum.de/UltraBoard/Images/Sad.gif" border="0" align="middle">
FW_ALLOW_INCOMING_HIGHPORTS_TCP="yes"
# Common: "DNS" or "domain ntp", better is "yes" to be sure ...
FW_ALLOW_INCOMING_HIGHPORTS_UDP="yes"

#
# 12.)
# Are you running some of the services below?
# They need special attention - otherwise they won´t work!
#
# Set services you are running to "yes", all others to "no", defaults to "no"
#
FW_SERVICE_AUTODETECT="yes" # Autodetect the services below when starting
#
# If you are running bind/named set to yes. Remember that you have to open
# port 53 (or "domain") as udp/tcp to allow incoming queries.
# Also FW_ALLOW_INCOMING_HIGHPORTS_UDP needs to be "yes"
FW_SERVICE_DNS="yes"
#
# if you use dhclient to get an ip address you have to set this to "yes" !
FW_SERVICE_DHCLIENT="no"
#
# set to "yes" if this server is a DHCP server
FW_SERVICE_DHCPD="yes"
#
# set to "yes" if this server is running squid. You still have to open the
# tcp port 3128 to allow remote access to the squid proxy service.
FW_SERVICE_SQUID="yes"
#
# set to "yes" if this server is running a samba server. You still have to open
# the tcp port 139 to allow remote access to SAMBA.
FW_SERVICE_SAMBA="yes"

#
# 13.)
# Which services accessed from the internet should be allowed to the
# dmz (or internal network - if it is not masqueraded)?
# REQUIRES: FW_ROUTE
#
# With this option you may allow access to e.g. your mailserver. The
# machines must have valid, non-private, IP addresses which were assigned to
# you by your ISP. This opens a direct link to your network, so only use
# this option for access to your dmz!!!!
#
# Choice: leave empty (good choice!) or use the following explained syntax
# of forwarding rules, seperated each by a space.
# A forwarding rule consists of 1) source IP/net and 2) destination IP
# seperated by a comma. e.g. "1.1.1.1,2.2.2.2 3.3.3.3/16,4.4.4.4/24"
# Optional is a protocol, seperated by a comma, e.g. "5.5.5.5,6.6.6.6,igmp"
# Optional is a port after the protocol with a comma, e.g. "0/0,0/0,udp,514"
#
FW_FORWARD="" # Beware to use this!

#
# 14.)
# Which services accessed from the internet should be allowed to masqueraded
# servers (on the internal network or dmz)?
# REQUIRES: FW_ROUTE
#
# With this option you may allow access to e.g. your mailserver. The
# machines must be in a masqueraded segment and may not have public IP addesses!
# Hint: if FW_DEV_MASQ is set to the external interface you have to set
# FW_FORWARD from internal to DMZ for the service as well to allow access
# from internal!
#
# Please note that this should *not* be used for security reasons! You are
# opening a hole to your precious internal network. If e.g. the webserver there
# is compromised - your full internal network is compromised!!
#
# Choice: leave empty (good choice!) or use the following explained syntax
# of forward masquerade rules, seperated each by a space.
# A forward masquerade rule consists of 1) source IP/net, 2) destination IP
# (dmz/intern), 3) a protocol (tcp/udp only!) and 4) destination port,
# seperated by a comma (","), e.g. "4.0.0.0/8,1.1.1.1,tcp,80"
# Optional is a port after the destination port, to redirect the request to
# a different destination port on the destination IP, e.g.
# "4.0.0.0/8,1.1.1.1,tcp,80,81"
#
FW_FORWARD_MASQ="" # Beware to use this!

#
# 15.)
# Which accesses to services should be redirected to a localport on the
# firewall machine?
#
# This can be used to force all internal users to surf via your squid proxy,
# or transparently redirect incoming webtraffic to a secure webserver.
#
# Choice: leave empty or use the following explained syntax of redirecting
# rules, seperated by a space.
# A redirecting rule consists of 1) source IP/net, 2) destination IP/net,
# 3) protocol (tcp or udp) 3) original destination port and 4) local port to
# redirect the traffic to, seperated by a colon. e.g.:
# "10.0.0.0/8,0/0,tcp,80,3128 0/0,172.20.1.1,tcp,80,8080"
#
FW_REDIRECT=""

#
# 16.)
# Which logging level should be enforced?
# You can define to log packets which were accepted or denied.
# You can also the set log level, the critical stuff or everything.
# Note that logging *_ALL is only for debugging purpose ...
#
# Choice: "yes" or "no", FW_LOG_*_CRIT defaults to "yes",
# FW_LOG_*_ALL defaults to "no"
#
FW_LOG_DROP_CRIT="yes"
#
FW_LOG_DROP_ALL="no"
#
FW_LOG_ACCEPT_CRIT="yes"
#
FW_LOG_ACCEPT_ALL="no"
#
# only change/activate this if you know what you are doing!
FW_LOG="--log-level warning --log-tcp-options --log-ip-option --log-prefix SuSE-FW"

#
# 17.)
# Do you want to enable additional kernel TCP/IP security features?
# If set to yes, some obscure kernel options are set.
# (icmp_ignore_bogus_error_responses, icmp_echoreply_rate,
# icmp_destunreach_rate, icmp_paramprob_rate, icmp_timeexeed_rate,
# ip_local_port_range, log_martians, mc_forwarding, mc_forwarding,
# rp_filter, routing flush)
# Tip: Set this to "no" until you have verified that you have got a
# configuration which works for you. Then set this to "yes" and keep it
# if everything still works. (It should!) <img src="http://www.pl-forum.de/UltraBoard/Images/Wilk.gif" border="0" align="middle">
#
# Choice: "yes" or "no", defaults to "yes"
#
FW_KERNEL_SECURITY="yes"

#
# 18.)
# Keep the routing set on, if the firewall rules are unloaded?
# REQUIRES: FW_ROUTE
#
# If you are using diald, or automatic dialing via ISDN, if packets need
# to be sent to the internet, you need to turn this on. The script will then
# not turn off routing and masquerading when stopped.
# You *might* also need this if you have got a DMZ.
# Please note that this is *insecure*! If you unload the rules, but are still
# connected, you might your internal network open to attacks!
# The better solution is to remove "/sbin/SuSEfirewall2 stop" or
# "/sbin/init.d/firewall stop" from the ip-down script!
#
#
# Choices "yes" or "no", defaults to "no"
#
FW_STOP_KEEP_ROUTING_STATE="yes"

#
# 19.)
# Allow (or don't) ICMP echo pings on either the firewall or the dmz from
# the internet? The internet option is for allowing the DMZ and the internal
# network to ping the internet.
# REQUIRES: FW_ROUTE for FW_ALLOW_PING_DMZ and FW_ALLOW_PING_INTERNET
#
# Choice: "yes" or "no", defaults to "no" if not set
#
FW_ALLOW_PING_FW="yes"
#
FW_ALLOW_PING_DMZ="no"
#
FW_ALLOW_PING_EXT="no"

##
# END of rc.firewall
##

# #
#-------------------------------------------------------------------------#
# #
# EXPERT OPTIONS - all others please don't change these! #
# #
#-------------------------------------------------------------------------#
# #

#
# 20.)
# Allow (or don't) ICMP time-to-live-exceeded to be send from your firewall.
# This is used for traceroutes to your firewall (or traceroute like tools).
#
# Please note that the unix traceroute only works if you say "yes" to
# FW_ALLOW_INCOMING_HIGHPORTS_UDP, and windows traceroutes only if you say
# additionally "yes" to FW_ALLOW_PING_FW
#
# Choice: "yes" or "no", defaults to "no"
#
FW_ALLOW_FW_TRACEROUTE="yes"

#
# 21.)
# Allow ICMP sourcequench from your ISP?
#
# If set to yes, the firewall will notice when connection is choking, however
# this opens yourself to a denial of service attack. Choose your poison.
#
# Choice: "yes" or "no", defaults to "yes"
#
FW_ALLOW_FW_SOURCEQUENCH="yes"

#
# 22.)
# Allow/Ignore IP Broadcasts?
#
# If set to yes, the firewall will not filter broadcasts by default.
# This is needed e.g. for Netbios/Samba, RIP, OSPF where the broadcast
# option is used.
# If you do not want to allow them however ignore the annoying log entries,
# set FW_IGNORE_FW_BROADCAST to yes.
#
# Choice: "yes" or "no", defaults to "no"
#
FW_ALLOW_FW_BROADCAST="no"
#
FW_IGNORE_FW_BROADCAST="yes"

#
# 23.)
# Allow same class routing per default?
# REQUIRES: FW_ROUTE
#
# Do you want to allow routing between interfaces of the same class
# (e.g. between all internet interfaces, or all internal network interfaces)
# be default (so without the need setting up FW_FORWARD definitions)?
#
# Choice: "yes" or "no", defaults to "no"
#
FW_ALLOW_CLASS_ROUTING="no"

#
# 25.)
# Do you want to load customary rules from a file?
#
# This is really an expert option. NO HELP WILL BE GIVEN FOR THIS!
# READ THE EXAMPLE CUSTOMARY FILE AT /etc/rc.config.d/firewall2-custom.rc.config
#
#FW_CUSTOMRULES="/etc/rc.config.d/firewall2-custom.rc.config"