1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379
|
\: vim:syntax=tex
\: this file maintained at http://git.mdcc.cx/uruk.git
\: this is a manpage in zoem format. see http://micans.org/zoem/ and man_zmm(7)
\import{pud/man.zmm}
\import{./include.zmm}
\begin{pud::man}{
{name}{uruk}
{html_title}{uruk}
{section}{8}
\man_share
}
\${html}{\"pud::man::maketoc"}
\sec{name}{NAME}
\NAME{uruk}{wrapper for Linux iptables, for managing firewall rules}
\sec{synopsis}{SYNOPSIS}
\uruk
\sec{description}{DESCRIPTION}
\uruk loads an \rc file (see \sibref{uruk-rc}{uruk-rc(5)}) which defines
network service access policy, and invokes \bf{iptables(8)} to set up firewall
rules implementing this policy. By default the file \ttrcpath is used; one can
overrule this by specifying another file in the URUK_CONFIG environment
variable. Under some circumstances, it's useful to use another command for
iptables; this can be achieved by setting the URUK_IPTABLES (and/or
URUK_IP6TABLES) environment variables. See \sibref{uruk-rc}{uruk-rc(5)} for
details.
\sec{quick setup guide}{QUICK SETUP GUIDE}
Uruk will \it{not} "just work" out of the box. It needs manual configuration.
For those of you who don't like reading lots of documentation:
\verbatim{\
# cp \expath \\
\rcpath
# vi \rcpath
# urukctl start}
\sec{getting started}{GETTING STARTED}
Once the \uruk script is installed, you want to go use it, of course. We'll
give a detailed description of what to do here.
\par{
First, create an \rc file. See \sibref{uruk-rc}{uruk-rc(5)} for info on how to
do this. Once this file is created and installed (this script looks in
\ttrcpath by default), you're ready to run \uruk. You might want to test your
\rc file by running \uruk in debug mode, see \sibref{uruk-rc}{uruk-rc(5)}.
There are at least 3 ways to load your \rc file. We'll first describe a low
level one: using vanilla iptables.
}
\cpar{Vanilla iptables}{
After editing \rc, load your rules like this. First flush your current rules:
\verbatim{\
# iptables -F
# ip6tables -F}
Then enable your \rc rules
\verbatim{\
# uruk}
. Inspect the rules by doing:
\verbatim{\
# iptables -L
# ip6tables -L}
.
If you want to make these changes survive a reboot, use the init script as
shipped with this package. If you'd rather write your own init script, the
\bf{iptables-restore(8)} and \bf{iptables-save(8)} commands from the iptables
package might be helpful.
}
\cpar{Using the Uruk init script}{
Assumed is the Uruk init script is installed as explained in the README file.
Optionally, install \tt{/etc/default/uruk} (or \tt{/etc/sysconfig/uruk}) and
tweak it. An example file is in \tt{\defpath} (You might like to enable
support for \uruk_save.) Now activate uruk by doing:
\verbatim{\
# urukctl start}
Now your pre-uruk iptables rules (if any) are saved as the "inactive" ruleset.
While executing \tt{urukctl start}, your box is open during a short while.
If you don't like this, read below about \uruk_save.
}
\par{
When rebooting, everything will be fine: \ttinitpath stores
state in \tt{\statepath/iptables}, using
iptables-save(8), which comes with Linux iptables.
}
\cpar{Using Debian ifupdown}{
In case you have just one network interface which should get protected, you
could use \bf{interfaces(5)} from the Debian ifupdown package instead of the
init script. Suppose you'd like to protect \tt{ppp0}, and would like not to
interfere with traffic on eth0: your other network interface.
First write an \rc file. Be sure it features
\verbatim{\
interfaces_unprotect="lo eth0"}
Then run:
\verbatim{\
# mkdir -p \statepath/iptables
# iptables -F
# iptables-save -c > \statepath/iptables/down
# uruk
# iptables-save -c > \statepath/iptables/up}
Add
\verbatim{\
pre-up iptables-restore < \statepath/iptables/up
post-down iptables-restore < \statepath/iptables/down}
to your interfaces stanza, in your \tt{/etc/network/interfaces} .
}
\par{
Similar tricks might be possible on GNU/Linux systems from other distributions.
The author is interested.
}
\sec{loading a new rc file}{LOADING A NEW \rc FILE}
Need to change your rules?
\cpar{Using the Uruk init script}{
Do
\verbatim{\
# vi \rcpath
# urukctl force-reload}
While executing \tt{urukctl force-reload}, your box is open during a short
while. If you don't like this, read below about \uruk_save.
}
\sec{the gory details uruk internals}{THE GORY DETAILS: uruk INTERNALS}
The \uruk script works like (and looks like) the list of statements below. Of
course, take a look at \tt{\sbinpath/uruk} for the final word on the workings.
\begin{itemize}{
{contiguous}{1}
{compact}{1}
{type}{arabic}
}
\item \rc is sourced as a shell script
\item Traffic on $interfaces_unprotect (just lo per default)
is trusted:
\verbatim{\
$iptables -A INPUT -i $iface -j ACCEPT}
\item $rc_a is sourced as a shell script, or, in case $rc_a is a directory, all
files matching $rc_a/*.rc are sourced as shell scripts
\item ESTABLISHED and RELATED packets are ACCEPT-ed:
\verbatim{\
$iptables -A INPUT -m conntrack --ctstate ESTABLISHED,RELATED \\
-j ACCEPT}
\item $rc_b is sourced
\item $interfaces gets protected against spoofing: we don't allow anyone to
spoof non-routeable addresses. We block outgoing packets that don't have
our address as source: they are either spoofed or something is
misconfigured (NAT disabled, for instance). We want to be nice and don't
send out garbage.
\verbatim{\
$iptables -A INPUT -i $iface --source $no_route_ip \\
-j DROP}
We drop all incoming packets which don't have us as destination:
\verbatim{\
$iptables -A OUTPUT -o $iface --source ! "$ip" \\
-j DROP}
And we always allow outgoing connections:
\verbatim{\
$iptables -A OUTPUT -m conntrack --ctstate NEW -o $iface \\
-j ACCEPT}
\item $rc_c is sourced
\item Allow traffic to offered services, from trusted sources:
\verbatim{\
$iptables -A INPUT -m conntrack --ctstate NEW \\
-i $iface --protocol $proto --source "$source" \\
--destination "$ip" --destination-port "$port" \\
-j ACCEPT}
\item $rc_d is sourced
\item Don't answer broadcast and multicast packets:
\verbatim{\
$iptables -A INPUT -i $iface --destination "$bcast" \\
-j DROP}
\item $rc_f is sourced
\item Explicitly allow a subset of the ICMP types. (We disallow all other
traffic later.)
\verbatim{\
$iptables -A INPUT --protocol icmp --icmp-type $type \\
-j ACCEPT}
\item $rc_g is sourced
\item Log packets (which make it till here)
\verbatim{\
$iptables -A INPUT -j LOG --log-level debug \\
--log-prefix 'iptables: '}
\item $rc_h is sourced
\item Reject all other packets
\verbatim{\
$iptables -A INPUT -j REJECT}
\item $rc_i is sourced
\end{itemize}
\sec{using uruk-save as the initscript backend}{USING uruk-save AS THE INITSCRIPT BACKEND}
By default, \uruk_save is not used by the uruk init script. You might want to
use it, though. The \uruk_save script is faster and when using \uruk_save,
your box won't be open while loading new rules. But beware: \uruk_save is not
as robust as using \uruk itself.
\par{
The script \urukctl (and thus the uruk init script) will use \uruk_save only if
asked to do so in \tt{/etc/default/uruk} (or \tt{/etc/sysconfig/uruk}). If
this file features
\verbatim{\
enable_uruk_save=true}
\uruk_save is used whenever appropriate.
See \sibref{uruk-save}{uruk-save(8)} for more details.
}
\sec{policy}{DEFAULT POLICY}
By default, \uruk drops packets which have unknown RFC 1918 private network
addresses in their source or destination.
\par{
It rejects packets with source nor destination for one of our IPs.
} \par{
Packets belonging to locally initiated sessions are allowed: we match state;
the local host can act as a client for any remote service.
} \par{
By default, \uruk drops all ICMP packets (except those for interfaces in
$interfaces_unprotect) with type other than
\begin{itemize}{
{contiguous}{1}
{compact}{1}
{type}{mark}
}
\item address-mask-reply
\item address-mask-request
\item destination-unreachable (this is a catch-all for a lot of types)
\item echo-request
\item echo-reply
\item parameter-problem (catch-all for ip-header-bad and required-option-missing)
\item timestamp-reply
\item timestamp-request
\item ttl-zero-during-transit
\item ttl-zero-during-reassembly
\end{itemize}
} \par{
By default, the FORWARD chain is left untouched, so has policy ACCEPT. (This
won't do much harm, since packet forwarding is disabled by default in the Linux
kernel. However, if you don't mind being paranoid, you might want to add a
\verbatim{\
iptables --policy FORWARD REJECT}
to your $rc_a uruk hook. See \sibref{uruk-rc}{uruk-rc(5)}.)
} \par{
By default, \uruk logs all UDP and TCP packets which are blocked by the user
defined policies. Loglevel is debug, logprefix is "iptables:". See
also the notes on \it{loglevel} in \sibref{uruk-rc}{uruk-rc(5)}.
} \par{
Blocked TCP packets are answered with a tcp-reset.
}
\sec{warning}{WARNING}
In order to keep the \uruk script small and simple, the script does very little
error handling. It does not check the contents of the \rc file in any way
before executing it. When your \rc file contains bogus stuff, \uruk will very
likely behave in unexpected ways. Caveat emptor.
\sec{environment}{ENVIRONMENT}
You can override some defaults in the shell before executing the uruk script.
\uruk honors the following variables:
\begin{itemize}{
{contiguous}{1}
{compact}{1}
{type}{mark}
}
\item "URUK_CONFIG" Full pathname of \rc file; \ttrcpath by default.
\item "URUK_IPTABLES" Full pathname of iptables executable.
\tt{/sbin/iptables} by default. Overrides \it{iptables}.
\item "URUK_IP6TABLES" Full pathname of ip6tables executable, for
IPv6 support. Overrides \it{ip6tables}.
\item "URUK_INTERFACES_UNPROTECT" Default list of unprotected interfaces.
Overrides \it{interfaces_unprotect}. The default default is \v{lo}.
\end{itemize}
\sec{see also}{SEE ALSO}
\sibref{uruk-rc}{uruk-rc(5)}, \sibref{uruk-save}{uruk-save(8)}. The Uruk homepage is at
\httpref{http://mdcc.cx/uruk/} .
\par{
\bf{iptables(8)}, \bf{iptables-save(8)},
\bf{iptables-restore(8)},
\bf{ip6tables(8)}, \bf{ip6tables-save(8)},
\bf{ip6tables-restore(8)}, \httpref{http://www.netfilter.org/}
\: (no manpage online :( )
} \par{
\bf{interfaces(5)}, \httpref{http://packages.debian.org/ifupdown}.
}
\sec{copyright}{COPYRIGHT}
Copyright (C) 2003 Stichting LogReport Foundation logreport@logreport.org;
Copyright (C) 2003, 2004 Tilburg University http://www.uvt.nl/;
Copyright (C) 2003-2013 \"man::author"
\gplheader
\sec{author}{AUTHOR}
\"man::author"
\end{pud::man}
|