Cristian Rodriguez R.
Copyright © 2001-2020 Thomas M. Eastep
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, with no Front-Cover, and with no Back-Cover Texts. A copy of the license is included in the section entitled “GNU Free Documentation License”.
2020/02/16
Abstract
In addition to those applications described in the /etc/shorewall/rules documentation, here are some other services/applications that you may need to configure your firewall to accommodate.
Table of Contents
- Important Notes
- Auth (identd)
- BitTorrent
- DNS
- Emule
- FTP
- Gnutella
- ICQ/AIM
- IMAP
- IPsec
- LDAP
- My\SQL™
- NFS
- NTP (Network Time Protocol)
- PCAnywhere™
- POP3
- PPTP
- rdate
- rsync
- Siproxd
- SSH/SFTP
- SMB/NMB (Samba/Windows™ Browsing/File Sharing)
- SMTP
- SNMP
- SVN
- Telnet
- TFTP
- Traceroute
- Usenet (NNTP)
- VNC
- Vonage™
- Web Access
- Webmin
- Whois
- X/XDMCP
- Other Source of Port Information
Caution
This article applies to Shorewall 3.0 and later. If you are running a version of Shorewall earlier than Shorewall 3.0.0 then please see the documentation for that release
Note
Shorewall distribution contains a library of user-defined macros
that allow for easily allowing or blocking a particular application.
ls /usr/share/shorewall/macro.*
for the list of macros in your distribution. If you find what you need,
you simply use the macro in a rule. For example, to allow DNS queries
from the dmz zone to the net zone:
#ACTION SOURCE DEST DNS(ACCEPT) dmz net
Note
In the rules that are shown in this document, the ACTION is shown as ACCEPT. You may need to use DNAT (see FAQ 30) or you may want DROP or REJECT if you are trying to block the application.
Example: You want to port forward FTP from the net to your server at 192.168.1.4 in your DMZ. The FTP section below gives you:
#ACTION SOURCE DEST PROTO DPORT FTP(ACCEPT) <source> <destination>
You would code your rule as follows:
#ACTION SOURCE DESTINATION PROTO DPORT FTP(DNAT) net dmz:192.168.1.4
Caution
It is now the 21st Century ; don't use identd in production anymore.
#ACTION SOURCE DESTINATION PROTO DPORT Auth(ACCEPT) <source> <destination>
Caution
This information is valid only for Shorewall 3.2 or later.
Caution
This rule assumes that your BitTorrent client listens on the default port(s)
#ACTION SOURCE DESTINATION PROTO DPORT BitTorrent(ACCEPT)<source> <destination>
#ACTION SOURCE DESTINATION PROTO DPORT DNS(ACCEPT) <source> <destination>
Note that if you are setting up a DNS server that supports recursive resolution, the server is the <destination> for resolution requests (from clients) and is also the <source> of recursive resolution requests (usually to other servers in the 'net' zone). So for example, if you have a public DNS server in your DMZ that supports recursive resolution for local clients then you would need:
#ACTION SOURCE DESTINATION PROTO DPORT DNS(ACCEPT) all dmz DNS(ACCEPT) dmz net
Note
Recursive Resolution means that if the server itself can't resolve the name presented to it, the server will attempt to resolve the name with the help of other servers.
Caution
This information is valid only for Shorewall 3.2 or later.
In contrast to how the rest of this article is organized, for emule I will give you the rules necessary to run emule on a single machine in your loc network (since that's what 99.99% of you want to do). Assume that:
The internal machine running emule has IP address 192.168.1.4.
You use Masquerading or SNAT for the local network.
The zones are named as they are in the two- and three-interface QuickStart guides).
Your loc->net policy is ACCEPT
/etc/shorewall/rules:
#ACTION SOURCE DESTINATION PROTO DPORT Edonkey(DNAT) net loc:192.168.1.4 #if you wish to enable the Emule webserver, add this rule too. DNAT net loc:192.168.1.4 tcp 4711
#ACTION SOURCE DESTINATION PROTO DPORT FTP(ACCEPT) <source> <destination>
Look here for much more information.
The internal machine running a Gnutella Client has IP address 192.168.1.4.
You use Masquerading or SNAT for the local network.
The zones are named as they are in the two- and three-interface QuickStart guides).
Your loc->net policy is ACCEPT
#ACTION SOURCE DESTINATION PROTO DPORT Gnutella(DNAT) net loc:192.168.1.4
Caution
When accessing your mail from the Internet, use only IMAP over SSL.
Caution
This information is valid only for Shorewall 3.2 or later.
#ACTION SOURCE DESTINATION PROTO DPORT IMAP(ACCEPT) <source> <destination> # Unsecure IMAP IMAPS(ACCEPT) <source> <destination> # IMAP over SSL.
#ACTION SOURCE DESTINATION PROTO DPORT ACCEPT <source> <destination> 50 ACCEPT <source> <destination> 51 ACCEPT <source> <destination> udp 500 ACCEPT <destination> <source> 50 ACCEPT <destination> <source> 51 ACCEPT <destination> <source> udp 500
Caution
This information is valid only for Shorewall 3.2 or later.
#ACTION SOURCE DESTINATION PROTO DPORT LDAP(ACCEPT) <source> <destination> #Insecure LDAP LDAPS(ACCEPT) <source> <destination> # LDAP over SSL
Caution
This information is valid only for Shorewall 3.2 or later.
Caution
Allowing access from untrusted hosts to your MySQL™ server represents a severe security risk.
DO NOT USE THIS if you don't know how to deal with the consequences, you have been warned.
#ACTION SOURCE DESTINATION PROTO DPORT MySQL(ACCEPT) <source> <destination>
#ACTION SOURCE DESTINATION PROTO DPORT ACCEPT <z1>:<list of client IPs> <z2>:a.b.c.d tcp 111 ACCEPT <z1>:<list of client IPs> <z2>:a.b.c.d udp
For more NFS information, see http://lists.shorewall.net/~kb/.
#ACTION SOURCE DESTINATION PROTO DPORT NTP(ACCEPT) <source> <destination>
Caution
If Possible , Avoid this protocol , use IMAP instead.
Caution
This information is valid only for Shorewall 3.2 or later
#ACTION SOURCE DESTINATION PROTO DPORT POP3(ACCEPT) <source> <destination> # Secure POP3S(ACCEPT) <source> <destination> #Unsecure Pop3
#ACTION SOURCE DESTINATION PROTO DPORT ACCEPT <source> <destination> 47 ACCEPT <source> <destination> tcp 1723
Caution
This assumes siproxd is running on the firewall and is using the default ports.
#ACTION SOURCE DESTINATION PROTO DPORT REDIRECT loc 5060 udp 5060 ACCEPT net fw udp 5060 ACCEPT net fw udp 7070:7089
#ACTION SOURCE DESTINATION PROTO DPORT SMB(ACCEPT) <source> <destination> SMB(ACCEPT) <destination> <source>
Also, see this page.
Caution
This information is valid only for Shorewall 3.2 or later.
#ACTION SOURCE DESTINATION PROTO DPORT SMTP(ACCEPT) <source> <destination> #Insecure SMTP SMTPS(ACCEPT) <source> <destination> #SMTP over SSL (TLS)
Caution
This information is valid only for Shorewall 3.2 or later.
Caution
This rule is for Subversion running in svnserve mode only.
#ACTION SOURCE DESTINATION PROTO DPORT SVN(ACCEPT) <source> <destination>
Caution
The telnet protocol is very insecure, don't use it.
#ACTION SOURCE DESTINATION PROTO DPORT Telnet(ACCEPT) <source> <destination>
You must have TFTP connection tracking support in your kernel. If
modularized, the modules are ip_conntrack_tftp (and ip_nat_tftp if any form of NAT is involved) These
modules may be loaded using entries in
/etc/shorewall/modules. The ip_conntrack_tftp module must be loaded first. Note
that the /etc/shorewall/modules file released with
recent Shorewall versions contains entries for these modules.
#ACTION SOURCE DESTINATION PROTO DPORT ACCEPT <source> <destination> udp 69
#ACTION SOURCE DESTINATION PROTO DPORT Trcrt(ACCEPT) <source> <destination> #Good for 10 hops
UDP traceroute uses ports 33434 through 33434+<max number of hops>-1. Note that for the firewall to respond with a TTL expired ICMP reply, you will need to allow ICMP 11 outbound from the firewall. The standard Shorewall sample configurations all set this up for you automatically since those sample configurations enable all ICMP packet types originating on the firewall itself.
#ACTION SOURCE DESTINATION PROTO DPORT ACCEPT fw net icmp ACCEPT fw loc icmp ACCEPT fw ...
#ACTION SOURCE DESTINATION PROTO DPORT NNTP(ACCEPT) <source> <destination> NNTPS(ACCEPT) <source> <destination> # secure NNTP
TCP Port 119
Caution
This information is valid only for Shorewall 3.2 or later.
Vncviewer to Vncserver -- TCP port 5900 + <display number>.
the following rule handles VNC traffic for VNC displays 0 - 9.
#ACTION SOURCE DESTINATION PROTO DPORT VNC(ACCEPT) <source> <destination>
Vncserver to Vncviewer in listen mode -- TCP port 5500.
#ACTION SOURCE DESTINATION PROTO DPORT VNCL(ACCEPT) <source> <destination>
The standard Shorewall loc->net ACCEPT policy is all that is required for Vonage™ IP phone service to work, provided that you have loaded the tftp helper modules (add the following entries to /etc/shorewall/modules if they are not there already):
Caution
This information is valid for Shorewall 3.2 or later.
#ACTION SOURCE DESTINATION PROTO DPORT HTTP(ACCEPT) <source> <destination> #Insecure HTTP HTTPS(ACCEPT) <source> <destination> #Secure HTTP
#ACTION SOURCE DESTINATION PROTO DPORT Webmin(ACCEPT) <source> <destination>
Webmin use TCP port 10000.
Assume that the Chooser and/or X Server are running at <chooser> and the Display Manager/X applications are running at <apps>.
#ACTION SOURCE DESTINATION PROTO DPORT ACCEPT <chooser> <apps> udp 177 #XDMCP ACCEPT <apps> <chooser> tcp 6000:6009 #X Displays 0-9
Didn't find what you are looking for -- have you looked in your own /etc/services file?
Still looking? Try http://www.networkice.com/advice/Exploits/Ports
