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#! /bin/bash
### Script to set up an iodine tunnel route traffic through it
###
### Copyright 2008 Barak A. Pearlmutter <bap@debian.org>
###
### License: MIT
###
### Permission to use, copy, modify, and distribute this software for
### any purpose with or without fee is hereby granted, provided that
### the above copyright notice and this permission notice appear in
### all copies.
###
### THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
### WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
### WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
### AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR
### CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
### LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
### NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
### CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
## Cause script to bail immediately on failed command
set -e
function usage
{
cat <<EOF
'iodine-client-start' starts an iodine IP-over-DNS tunnel.
Usage: iodine-client-start [option]
-h, --help Print help and exit
-v, --version Print version info and exit
Invoking the program without options attempts to set up and configure
an iodine IP-over-DNS tunnel using the configuration in the file
/etc/default/iodine-client or by querying the user. It tries to
figure out the right way to set things up by observing the network,
and if all else fails by guessing.
QUICK CONFIGURATION
Put two lines in the file /etc/default/iodine-client
subdomain=your.tunnel.sub.domain
passwd=password_for_that_tunnel
or invoke the script with those environment variables set:
env subdomain=xxx passwd=xxx iodine-client-start
If these are not set, the script will query the user for them.
DETAILS
The configuration file consists of lines which are either comments
starting with '#', or settings of the form VAR="val". Valid VARs are:
subdomain
Sample value: your.tunnel.sub.domain (no default, must be set)
passwd
Sample value: password_for_that_tunnel (no default, must be set)
testhost
Hostname to ping when testing if network is working (default:
slashdot.org)
bounce_localnet
Take the local network down and then up again before starting
tunnel (default: false)
test_ping_localnet
Test if the local network is working by pinging the gateway
(default: true)
test_ping_tunnel
Test if the iodine tunnel is working after it has been set up by
pinging the host at the other end (default: true)
test_ping_final
Test if the tunnel is working after everything is ostensibly set
up by trying to ping an external host (default: true)
default_router
IP address of router on the local network---should be found
automatically, set this if that fails and the program guesses wrong.
interface
Interface to use (e.g., eth1, eth0, etc) for connection to DNS
server used for the iodine tunnel---should be found automatically,
set this if that fails and the program guesses wrong.
mtu
Set if tunnel MTU needs to be manually changed (lowered). Should
not be necessary anymore, as recent versions of iodine negotiate
an appropriate MTU during tunnel setup. But if that negotiation
does not happen, or if you are using an older version of iodine,
the default tunnel MTU is 1024, and if the local DNS server
restricts to 512 byte packets you might need to use an MTU of 220.
skip_raw_udp_mode
Set "-r" option in iodine command line. With this option, iodine
does not try to establish a direct UDP socket to the iodine server
on port 53. (default: true).
continue_on_error
Set if the script should continue even if a command fails.
Use to test script when running as non-root. Defaults to false
if running as root, true otherwise.
EOF
}
function version
{
echo iodine-client-start 1.0.6
}
case $# in
0)
;;
1)
case "$1" in
# start)
# ;;
# stop)
# ;;
# restart)
# ;;
--version|-v)
version
exit
;;
--help|-h)
usage
exit
;;
*)
echo error: unknown option "$1"
exit 1
esac
exit
;;
*)
echo error: too many arguments "$*"
exit 1
;;
esac
echo "${iodine_client_rc:=/etc/default/iodine-client}" > /dev/null
if [ -r ${iodine_client_rc} ]; then
. ${iodine_client_rc}
else
echo WARNING: Cannot read ${iodine_client_rc}
fi
if [ -z ${subdomain} ]; then
read -p "DNS tunnel DNS subdomain: " subdomain
fi
if [ -z ${subdomain} ]; then
echo ERROR: Must set subdomain.
exit 1
fi
if [ -z ${passwd} ]; then
read -p "Password for DNS tunnel over ${subdomain}: " passwd
fi
## This is a host name used for testing DNS and for pinging
echo "${testhost:=slashdot.org}" > /dev/null
## Set if local network should be taken down and then up
echo "${bounce_localnet:=false}" > /dev/null
## Set for testing network availability via ping at various points
echo "${test_ping_localnet:=true}" > /dev/null
echo "${test_ping_tunnel:=true}" > /dev/null
echo "${test_ping_final:=true}" > /dev/null
## Set if the script cannot find and then incorrectly guesses the
## local network router
echo "${default_router}" > /dev/null
## Set if script uses the wrong hardware interface
echo "${interface}" > /dev/null
## Set if MTU needs to be manually altered (lowered)
## - the default tunnel MTU is 1024.
## - if local DNS server restricts to 512 byte packets then use MTU 220
echo "${mtu}" > /dev/null
## Set it if you want try RAW udp mode
echo "${skip_raw_udp_mode:=true}" > /dev/null
## Set if the script should continue even if a command fails.
## Used to test script when running as non-root.
if [ $(whoami) = root ]; then
echo "${continue_on_error:=false}" > /dev/null
else
echo "${continue_on_error:=true}" > /dev/null
fi
## DEBIAN PACKAGES TO INSTALL: these are needed to run this script
## iodine (for /usr/sbin/iodine)
## iproute (for /bin/ip)
## ipcalc (for /usr/bin/ipcalc)
## dnsutils (for /usr/bin/dig)
## fping (for /usr/bin/fping)
## or oping (for /usr/bin/oping)
## gawk (for /usr/bin/gawk, to use gensub())
if type -P fping > /dev/null; then
ping_cmd="fping -C1"
elif type -P oping > /dev/null; then
ping_cmd="oping -c1"
else
ping_cmd="echo would ping"
fi
## TO DO
## - avoid double ping when DNS server and local router are the same
## - option to not kill existing iodine DNS tunnels, in case there
## are meant to be more than one
## - sanify check whether default_router is on local network
echo ==== Creating IP-over-DNS tunnel over local network connection...
## Find a network interface
if [ -z ${interface} ]; then
interfaces=$(tail --lines=+3 /proc/net/wireless \
| tr -d : | awk '{print $1}')
for dev in ${interfaces}; do
if ip -oneline -4 addr show dev ${dev} | grep -q inet; then
interface=${dev}
fi
done
fi
if [ -z ${interface} ]; then
interface=$(ip -oneline link show | awk '$16=="link/ether" {print $2}' | tr -d : | head -1)
fi
if [ -z ${interface} ]; then
echo ERROR: No network interface found.
exit 1
fi
echo ==== Local network interface: ${interface}
## Down any existing DNS tunnel (wish there were "approved" way to do this)
echo ==== Killing existing DNS tunnels...
if killall --quiet --wait --verbose --signal HUP iodine; then
sleep 2
fi
## Stabilize local network
if ${bounce_localnet}; then
echo ==== Bouncing local network connection...
ifdown --force ${interface} || true
ifup ${interface} || ${continue_on_error}
fi
## Fetch some information about the local network
addr=$(ip -oneline -4 addr show dev ${interface} scope global \
| awk '{print $4}' | head -1)
prefix_len=$(echo ${addr} | sed 'sX^.*/XX')
local_net=$(ipcalc --nobinary ${addr} | awk '$1=="Network:" {print $2}')
echo ==== Local address: ${addr}
echo ==== Local network: ${local_net}
router=$(ip -oneline -4 route list dev ${interface} default \
| awk '{print $3}' | head -1)
if [ -z ${router} ]; then
## This can happen when the default local route is already deleted
if [ -z ${default_router} ]; then
echo WARNING: no default route, guessing local router IP address.
## Minimum address on local net is usually right
router=$(ipcalc --nobinary ${addr} | awk '$1=="HostMin:" {print $2}')
else
echo WARNING: no default route, using configured default router.
## But sometimes need to hardwire...
router=${default_router}
fi
fi
echo ==== Local network router: ${router}
## Test DNS service
testhost_ip=$(dig +short -t A -q ${testhost})
if [ -z ${testhost_ip} ]; then
echo WARNING: Failure on DNS lookup of ${testhost}.
fi
## fetch DNS servers
nameservers=$(awk '$1=="nameserver" {print $2}' /etc/resolv.conf)
if [ -n "${nameservers}" ]; then
echo ==== DNS servers: ${nameservers}
else
echo ERROR: No DNS servers found.
exit 1
fi
## Test if local network is up
if ${test_ping_localnet}; then
echo ==== Ping test of local network router and DNS servers...
${ping_cmd} ${router} ${nameservers} \
|| echo WARNING: Ping test failed.
fi
## Add point-to-point routes for any non-local DNS servers
for n in ${nameservers}; do
n_net=$(ipcalc --nobinary ${n}/${prefix_len} | awk '$1=="Network:" {print $2}')
n_net8=$(ipcalc --nobinary ${n}/8 | awk '$1=="Network:" {print $2}')
if [ "${n_net}" != "${local_net}" ]; then
if [ "${n_net8}" != "127.0.0.0/8" ]; then
echo ==== Adding point-to-point route for DNS server ${n}
## remove point-to-point route first, in case it is already present
ip -4 route del ${n}/32 || true
ip -4 route add ${n}/32 via ${router} || ${continue_on_error}
fi
fi
done
## Bring up DNS tunnel
echo ==== Creating IP-over-DNS tunnel...
if ${skip_raw_udp_mode}; then
iodine_opts="${iodine_opts} -r"
fi
iodine ${iodine_opts} -P "${passwd}" "${subdomain}" || ${continue_on_error}
## Find DNS tunnel interface
tunnel_interface=$(ip -oneline link show | gawk '$2 ~ /^dns/ {print $2}' | tr -d : | head -1)
if [ -z "${tunnel_interface}" ]; then
echo WARNING: Cannot find DNS tunnel interface, using default.
tunnel_interface=dns0
fi
echo ==== DNS tunnel interface: ${tunnel_interface}
## Maybe try to change MTU
if [ -n "${mtu}" ]; then
echo ==== Setting MTU of ${tunnel_interface} to ${mtu}
ip link set ${tunnel_interface} mtu ${mtu}
fi
## Figure out router at other end of tunnel, assuming router uses final octet .1
## (There should be some way to get this information out of iodine, since
## it *prints* it as it sets up the tunnel, so it does know it.)
tunnel_remote=$(ip -oneline -4 address show dev ${tunnel_interface} \
| gawk '$3=="inet" {print gensub("[.][0-9]*/.*", ".1", 1, $4)}' | head -1)
if [ -z ${tunnel_remote} ]; then
echo ERROR: Cannot find DNS tunnel remote endpoint.
${continue_on_error}
## set something random if debugging
echo WARNING: Confabulating DNS tunnel remote endpoint.
tunnel_remote=192.168.253.1
fi
echo ==== DNS tunnel remote endpoint: ${tunnel_remote}
if ${test_ping_tunnel}; then
echo ==== Ping test of local router, nameserver, and DNS tunnel...
${ping_cmd} ${router} ${nameservers} ${tunnel_remote} \
|| echo WARNING: Ping test failed.
fi
## Modify routing table to send trafic via DNS tunnel
echo ==== Setting default route through DNS tunnel...
## Remove default route via local router
ip -4 route del default via ${router} || echo WARNING: No default route to delete
## Add default via tunnel
ip -4 route add default via ${tunnel_remote} || ${continue_on_error}
## Test if all is well
if ${test_ping_final}; then
echo ==== Ping test of local router, nameserver, DNS tunnel, external test host...
${ping_cmd} ${router} ${nameservers} ${tunnel_remote} ${testhost_ip:-${testhost}} \
|| echo WARNING: Ping test failed.
fi