1 \chapter{Dealing with Firewalls}
2 \label{FirewallsChapter}
3 \index[general]{Dealing with Firewalls }
4 \index[general]{Firewalls!Dealing with }
6 If you have a firewall or a DMZ installed on your computer, you may experience
7 difficulties contacting one or more of the Clients to back them up. This is
8 especially true if you are trying to backup a Client across the Internet.
10 \section{Technical Details}
11 \index[general]{Technical Details }
12 \index[general]{Details!Technical }
14 If you are attempting to do this, the sequence of network events in Bacula to
15 do a backup are the following:
25 Where hopefully it is obvious that DIR represents the Director, FD the File
26 daemon or client, and SD the Storage daemon. The numbers that follow those
27 names are the standard ports used by Bacula, and the \verb:->: represents the
28 left side making a connection to the right side (i.e. the right side is the
29 "server" or is listening on the specified port), and the left side is the
30 "client" that initiates the conversation.
32 Note, port 9103 serves both the Director and the File daemon, each having its
33 own independent connection.
35 If you are running {\bf iptables}, you might add something like:
38 -A FW-1-INPUT -m state --state NEW -m tcp -p tcp --dport 9101:9103 -j ACCEPT
44 -A FW-1-INPUT -m state --state NEW -m tcp -p tcp --dport 9102 -j ACCEPT
47 on your client. In both cases, I assume that the machine is allowed to
48 initiate connections on any port. If not, you will need to allow outgoing
49 connections on ports 9102 and 9103 on your server and 9103 on your client.
50 Thanks to Raymond Norton for this tip.
52 \section{A Concrete Example}
53 \index[general]{Example!Concrete }
54 \index[general]{Concrete Example }
56 The following discussion was originally written by
57 Jesse Guardiani because he has 'internal' and 'external' requiring the
58 Director and the Client to use different IP addresses. His original
59 solution was to define two different Storage resources in the Director's
60 conf file each pointing to the same Storage daemon but with different
61 IP addresses. In Bacula 1.38.x this no longer works, because Bacula makes
62 a one-to-one association between a Storage daemon resource and a Device (such
63 as an Autochanger). As a consequence, I have modified his original
64 text to a method that I believe will work, but is as of yet untested
67 My bacula server is on the 192.168.1.0/24 network at IP address 192.168.1.52.
68 For the sake of discussion we will refer to this network as the 'internal'
69 network because it connects to the internet through a NAT'd firewall. We will
70 call the network on the public (internet) side of the NAT'd firewall the
71 'external' network. Also, for the sake of discussion we will call my bacula
75 server.int.mydomain.tld
78 when a fully qualified domain name is required, or simply:
84 if a hostname is adequate. We will call the various bacula daemons running on
85 the server.int.mydomain.tld machine:
93 In addition, I have two clients that I want to back up with Bacula. The first
94 client is on the internal network. Its fully qualified domain name is:
97 private1.int.mydomain.tld
106 This machine is a client and therefore runs just one bacula daemon:
112 The second client is on the external network. Its fully qualified domain name
125 This machine also runs just one bacula daemon:
131 Finally, I have a NAT firewall/gateway with two network interfaces. The first
132 interface is on the internal network and serves as a gateway to the internet
133 for all the machines attached to the internal network (For example,
134 server.int.mydomain.tld and private1.int.mydomain.tld). The second interface
135 is on the external (internet) network. The external interface has been
139 firewall.mydomain.tld
145 *.int.mydomain.tld = internal network
146 *.mydomain.tld = external network
149 \subsection{The Bacula Configuration Files for the Above}
150 \index[general]{Above!Bacula Configuration Files for the }
151 \index[general]{Bacula Configuration Files for the Above }
153 server-sd manages a 4 tape AIT autoloader. All of my backups are written to
154 server-sd. I have just *one* Device resource in my server-sd.conf file:
158 Name = "autochanger1";\
160 Changer Device = /dev/ch0;
161 Changer Command = "/usr/local/sbin/chio-bacula %c %o %S %a";
167 Archive Device = /dev/nrsa1;
170 AutomaticMount = yes; # when device opened, read it
172 Hardware End of Medium = No
173 Fast Forward Space File = No
179 \ilink{the Tape Testing}{FreeBSDTapes} chapter of this manual
180 for important FreeBSD information.) However, unlike previously, there
181 is only one Storage definition in my server-dir.conf file:
185 Name = "autochanger1" # Storage device for backing up
186 Address = Storage-server
188 Password = "mysecretpassword"
189 Device = "autochanger1"
195 Note that the Storage resource uses neither of the two addresses to
196 the Storage daemon -- neither server.int.mydomain.tld nor
197 firewall.mydomain.tld, but instead uses the address Storage-server.
199 What is key is that in the internal net, Storage-server is resolved
200 to server.int.mydomain.tld, either with an entry in /etc/hosts, or by
201 creating and appropriate DNS entry, and on the external net (the Client
202 machine), Storage-server is resolved to firewall.mydomain.tld.
205 In addition to the above, I have two Client resources defined in
211 Address = private1.int.mydomain.tld
214 Password = "mysecretpassword" # password for FileDaemon
218 Address = public1.mydomain.tld
221 Password = "mysecretpassword" # password for FileDaemon
225 And finally, to tie it all together, I have two Job resources defined in
230 Name = "Private1-Backup"
234 Schedule = "WeeklyCycle"
235 Storage = "autochanger1-int"
238 Write Bootstrap = "/var/db/bacula/Private1-Backup.bsr"
242 Name = "Public1-Backup"
246 Schedule = "WeeklyCycle"
247 Storage = "autochanger1-ext"
250 Write Bootstrap = "/var/db/bacula/Public1-Backup.bsr"
255 It is important to notice that because the 'Private1-Backup' Job is intended
256 to back up a machine on the internal network so it resolves Storage-server
257 to contact the Storage daemon via the internal net.
258 On the other hand, the 'Public1-Backup' Job is intended to
259 back up a machine on the external network, so it resolves Storage-server
260 to contact the Storage daemon via the external net.
262 I have left the Pool, Catalog, Messages, FileSet, Schedule, and Director
263 resources out of the above server-dir.conf examples because they are not
264 pertinent to the discussion.
266 \subsection{How Does It Work?}
267 \index[general]{How Does It Work? }
268 \index[general]{Work!How Does It }
270 If I want to run a backup of private1.int.mydomain.tld and store that backup
271 using server-sd then my understanding of the order of events is this:
274 \item I execute my Bacula 'console' command on server.int.mydomain.tld.
275 \item console connects to server-dir.
276 \item I tell console to 'run' backup Job 'Private1-Backup'.
277 \item console relays this command to server-dir.
278 \item server-dir connects to private1-fd at private1.int.mydomain.tld:9102
279 \item server-dir tells private1-fd to start sending the files defined in the
280 'Private1-Backup' Job's FileSet resource to the Storage resource
281 'autochanger1', which we have defined in server-dir.conf as having the
282 address:port of Storage-server, which is mapped by DNS to server.int.mydomain.tld.
283 \item private1-fd connects to server.int.mydomain.tld:9103 and begins sending
287 Alternatively, if I want to run a backup of public1.mydomain.tld and store
288 that backup using server-sd then my understanding of the order of events is
292 \item I execute my Bacula 'console' command on server.int.mydomain.tld.
293 \item console connects to server-dir.
294 \item I tell console to 'run' backup Job 'Public1-Backup'.
295 \item console relays this command to server-dir.
296 \item server-dir connects, through the NAT'd firewall, to public1-fd at
297 public1.mydomain.tld:9102
298 \item server-dir tells public1-fd to start sending the files defined in the
299 'Public1-Backup' Job's FileSet resource to the Storage resource
300 'autochanger1', which we have defined in server-dir.conf as having the
301 same address:port as above of Storage-server, but which on this machine
302 is resolved to firewall.mydomain.tld:9103.
303 \item public1-fd connects to firewall.mydomain.tld:9103 and begins sending
307 \subsection{Important Note}
308 \index[general]{Important Note }
309 \index[general]{Note!Important }
311 In order for the above 'Public1-Backup' Job to succeed,
312 firewall.mydomain.tld:9103 MUST be forwarded using the firewall's
313 configuration software to server.int.mydomain.tld:9103. Some firewalls call
314 this 'Server Publication'. Others may call it 'Port Forwarding'.
316 \subsection{Firewall Problems}
317 \index[general]{Firewall Problems}
318 \index[general]{Problems!Firewalls}
319 Either a firewall or a router may decide to timeout and terminate
320 open connections if they are not active for a short time. By Internet
321 standards the period should be two hours, and should be indefinitely
322 extended if KEEPALIVE is set as is the case by Bacula. If your firewall
323 or router does not respect these rules, you may find Bacula connections
324 terminated. In that case, the first thing to try is turning on the
325 {\bf Heart Beat Interval} both in the File daemon and the Storage daemon
326 and set an interval of say five minutes.
328 Also, if you have denial of service rate limiting in your firewall, this
329 too can cause Bacula disconnects since Bacula can at times use very high
330 access rates. To avoid this, you should implement default accept
331 rules for the Bacula ports involved before the rate limiting rules.
333 Finally, if you have a Windows machine, it will most likely by default
334 disallow connections to the Bacula Windows File daemon. See the
335 Windows chapter of this manual for additional details.