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<!DOCTYPE html>
<html dir="ltr" lang="en">
<head>
<meta charset='utf-8'>
<title>2.2. Network</title>
</head>
<body>
<a href="index.html">Core OS Index</a>
<h1>2.2. Network</h1>
<p>Operation of the network can be handle with init scripts or with
<a href="#nm">network manager</a>;</p>
<dl>
<dt><a href="conf/rc.d/iptables">/etc/rc.d/iptables</a></dt>
<dd>Configure <a href="#iptables">iptables</a>, "start" option
loads set of rules from file /etc/iptables/(name).v4, "open" option
allows everything to outside and blocks everything from outside,
"stop" option will block and log everything.</dd>
<dt><a href="conf/rc.d/net">/etc/rc.d/net</a></dt>
<dd>Configure Ethernet interface with static or dynamic (dhcp)
IP, set default route and add default gateway.</dd>
<dt><a href="conf/rc.d/wlan">/etc/rc.d/wlan</a></dt>
<dd>Configure Wireless interface, launch wpa_supplicant to handle
wireless authenticationand dynamic (dhcp)
connection to router and add as default gateway.</dd>
<dt><a href="conf/rc.d/wlan">/etc/rc.d/networkmanager</a></dt>
<dd>Use network manager to handle connections.</dd>
</dl>
<p>Choose wireless (wlan), cable network (net) or network manager in
<a href="conf/rc.conf">/etc/rc.conf</a> to handle configuration of the
network at startup, example using network manager;</p>
<pre>
#
# /etc/rc.conf: system configuration
#
FONT=default
KEYMAP=dvorak
TIMEZONE="Europe/Lisbon"
HOSTNAME=machine
SYSLOG=sysklogd
SERVICES=(lo iptables networkmanager crond)
# End of file
</pre>
<p>If is first boot after install configure iptables and one of above
described scripts then proceed to
<a href="package.html#sysup">update system.</a></p>
<h2 id="resolv">2.2.1. Resolver</h2>
<p>This example will use
<a href="http://www.chaoscomputerclub.de/en/censorship/dns-howto">Chaos Computer Club</a>
server, edit /etc/resolv.conf and make it immutable;</p>
<pre>
# /etc/resolv.conf.head can replace this line
nameserver 2.2.73.91.35
# /etc/resolv.conf.tail can replace this line
</pre>
<pre>
# chattr +i /etc/resolv.conf
</pre>
<h2 id="static">2.2.2. Static IP</h2>
<p>Current example of <a href="conf/rc.d/net">/etc/rc.d/net</a>;</p>
<pre>
Address: 192.168.0.1 11000000.10101000.00000000 .00000001
Netmask: 255.255.255.0 = 24 11111111.11111111.11111111 .00000000
Wildcard: 0.0.0.255 00000000.00000000.00000000 .11111111
=>
Network: 192.168.0.0/24 11000000.10101000.00000000 .00000000 (Class C)
Broadcast: 192.168.0.255 11000000.10101000.00000000 .11111111
HostMin: 192.168.0.1 11000000.10101000.00000000 .00000001
HostMax: 192.168.0.254 11000000.10101000.00000000 .11111110
Hosts/Net: 254 (Private Internet)
</pre>
<p>Other IP class that can used for private network;</p>
<pre>
Address: 10.0.0.1 00001010.00000000.00000000 .00000001
Netmask: 255.255.255.0 = 24 11111111.11111111.11111111 .00000000
Wildcard: 0.0.0.255 00000000.00000000.00000000 .11111111
=>
Network: 10.0.0.0/24 00001010.00000000.00000000 .00000000 (Class A)
Broadcast: 10.0.0.255 00001010.00000000.00000000 .11111111
HostMin: 10.0.0.1 00001010.00000000.00000000 .00000001
HostMax: 10.0.0.254 00001010.00000000.00000000 .11111110
Hosts/Net: 254 (Private Internet)
</pre>
<p>Manual configuring like net script;</p>
<pre>
# DEV=enp8s0
# ADDR=192.168.1.9
# MASK=24
# GW=192.168.1.254
</pre>
<pre>
# ip addr flush dev ${DEV}
# ip route flush dev ${DEV}
# ip addr add ${ADDR}/${MASK} dev ${DEV} broadcast +
# ip link set ${DEV} up
# ip route add default via ${GW}
</pre>
<h2 id="iptables">2.2.3. Iptables</h2>
<p>For more information about firewall systems read arch wiki
<a href="https://wiki.archlinux.org/index.php/Iptables">iptables</a>
and <a href="https://wiki.archlinux.org/index.php/nftables">nftables</a>.</p>
<p>Diagram of a package route throw iptables;</p>
<pre>
XXXXXXXXXXXXXXXXX
XXXX Network XXXX
XXXXXXXXXXXXXXXXX
+
|
v
+-------------+ +------------------+
|table: filter| >---+ | table: nat |
|chain: INPUT | | | chain: PREROUTING|
+-----+-------+ | +--------+---------+
| | |
v | v
[local process] | **************** +--------------+
| +---------+ Routing decision +------< |table: filter |
v **************** |chain: FORWARD|
**************** +------+-------+
Routing decision |
**************** |
| |
v **************** |
+-------------+ +------< Routing decision >---------------+
|table: nat | | ****************
|chain: OUTPUT| | +
+-----+-------+ | |
| | v
v | +-------------------+
+--------------+ | | table: nat |
|table: filter | +----+ | chain: POSTROUTING|
|chain: OUTPUT | +--------+----------+
+--------------+ |
v
XXXXXXXXXXXXXXXXX
XXXX Network XXXX
XXXXXXXXXXXXXXXXX
</pre>
<p>Command line usage;</p>
<pre>
iptables [-t table] {-A|-C|-D} chain rule-specification
iptables [-t table] {-A|-C|-D} chain rule-specification
iptables [-t table] -I chain [rulenum] rule-specification
iptables [-t table] -R chain rulenum rule-specification
iptables [-t table] -D chain rulenum
iptables [-t table] -S [chain [rulenum]]
iptables [-t table] {-F|-L|-Z} [chain [rulenum]] [options...]
iptables [-t table] -N chain
iptables [-t table] -X [chain]
iptables [-t table] -P chain target
iptables [-t table] -E old-chain-name new-chain-name
rule-specification = [matches...] [target]
match = -m matchname [per-match-options]
</pre>
<p>Targets, can be a user defined chain;</p>
<pre>
ACCEPT - accepts the packet
DROP - drop the packet on the floor
QUEUE - packet will be stent to queue
RETURN - stop traversing this chain and
resume ate the next rule in the
previeus (calling) chain.
if packet reach the end of the chain or
a target RETURN, default policy for that
chain is applayed.
</pre>
<p>Target Extensions</p>
<pre>
AUDIT
CHECKSUM
CLASSIFY
DNAT
DSCP
LOG
Torn on kernel logging, will print some
some information on all matching packets.
Log data can be read with dmesg or syslogd.
This is a non-terminating target and a rule
should be created with matching criteria.
--log-level level
Level of logging (numeric or see sys-
log.conf(5)
--log-prefix prefix
Prefix log messages with specified prefix
up to 29 chars log
--log-uid
Log the userid of the process with gener-
ated the packet
NFLOG
This target pass the packet to loaded logging
backend to log the packet. One or more userspace
processes may subscribe to the group to receive
the packets.
ULOG
This target provides userspace logging of maching
packets. One or more userspace processes may then
then subscribe to various multicast groups and
then receive the packets.
</pre>
<p>Commands</p>
<pre>
-A, --append chain rule-specification
-C, --check chain rule-specification
-D, --delete chain rule-specification
-D, --delete chain rulenum
-I, --insert chain [rulenum] rule-specification
-R, --replace chain rulenum rule-specification
-L, --list [chain]
-P, --policy chain target
</pre>
<p>Parameters</p>
<pre>
-p, --protocol protocol
tcp, udp, udplite, icmp, esp, ah, sctp, all
-s, --source address[/mask][,...]
-d, --destination address[/mask][,...]
-j, --jump target
-g, --goto chain
-i, --in-interface name
-o, --out-interface name
-f, --fragment
-m, --match options module-name
iptables can use extended packet matching
modules.
-c, --set-counters packets bytes
</pre>
<p>See current rules and packets counts;</p>
<pre>
# iptables -L -n -v | less
</pre>
<h3 id="ipt_scripts">2.2.3.1. Iptable scripts</h3>
<p>Scripts help to setup iptables rules so they can be saved using iptables-save
and later restored using iptables-restore utilities. Init script
<a href="conf/rc.d/iptables">/etc/rc.d/iptables</a>
loads set of rules from /etc/iptables folder at boot time.
Start option "open" option allows everything to outside
and blocks new connections from outside, "stop" will block and log
everything.</p>
<p>Setup init script and rules;</p>
<pre>
# mkdir /etc/iptables
# cp core/conf/iptables/*.sh /etc/iptables/
# cp core/conf/rc.d/iptables /etc/rc.d/
# chmod +x /etc/rc.d/iptables
</pre>
<p>Change /etc/rc.conf and add iptables;</p>
<pre>
SERVICES=(iptables lo net crond)
</pre>
<p>Change <a href="conf/rc.d/iptables">/etc/rc.d/iptables</a> and define type; server, bridge or open.</p>
<p>Adjust <a href="conf/ipt-conf.sh">/etc/iptables/ipt-conf.sh</a>
with your network configuration, and adjust
<a href="conf/ipt-server.sh">/etc/iptables/ipt-server.sh</a>, <a href="conf/ipt-bridge.sh">/etc/iptables/ipt-bridge.sh</a>, <a href="conf/ipt-open.sh">/etc/iptables/ipt-open.sh</a> according with host necessities.</p>
<p>When is everything configured run script to load the rules and save them on /etc/iptables. Example for bridge setup;</p>
<pre>
# cd /etc/iptables
# bash ipt-bridge.sh
</pre>
<p>From now on use /etc/rc.d/iptables to start and stop.<p>
<h2 id="wpa">2.2.4. Wpa and dhcpd</h2>
<p>There is more information on
<a href="http://crux.nu/Wiki/WifiStartScripts">Wiki Wifi Start Scripts</a> and
see <a href="conf/rc.d/wlan">/etc/rc.d/wlan</a>. Manual or first time configuration;</p>
<pre>
# ip link
</pre>
<pre>
# iwlist wlp2s0 scan
</pre>
<pre>
# iwconfig wlp2s0 essid NAME key s:ABCDE12345
</pre>
<h3>2.2.4.1. Wpa Supplicant</h3>
<p>Configure wpa supplicant edit;</p>
<pre>
# vim /etc/wpa_supplicant.conf
</pre>
<pre>
ctrl_interface=/var/run/wpa_supplicant
update_config=1
fast_reauth=1
ap_scan=1
</pre>
<pre>
# wpa_passphrase <ssid> <password> >> /etc/wpa_supplicant.conf
</pre>
<p>Now start wpa_supplicant with:</p>
<pre>
# wpa_supplicant -B -i wlp2s0 -c /etc/wpa_supplicant.conf
Successfully initialized wpa_supplicant
</pre>
<p>Use <a href="conf/rc.d/wlan">/etc/rc.d/wlan</a>
init script to auto load wpa configuration and dhcp
client.</p>
<h3>2.2.4.2. Wpa Cli</h3>
<pre>
# wpa_cli
> status
</pre>
<pre>
> add_network
3
</pre>
<pre>
> set_network 3 ssid "Crux-Network"
OK
</pre>
<pre>
> set_network 3 psk "uber-secret-pass"
OK
</pre>
<pre>
> enable_network 3
OK
</pre>
<pre>
> list_networks
</pre>
<pre>
> select_network 3
</pre>
<pre>
> save_config
</pre>
<h2 id="nm">2.2.5. Network Manager</h2>
<p>Wifi status;</p>
<pre>
$ nmcli radio wifi
$ nmcli radio wifi on
</pre>
<p>List wifi networks;</p>
<pre>
$ nmcli device wifi rescan
$ nmcli device wifi list
</pre>
<p>Connect to a wifi network;</p>
<pre>
$ nmcli device wifi connect "network name" password "network password"
</pre>
<p>Edit and save network configuration;</p>
<pre>
$ nmcli connection edit "network name"
nmcli> save persistent
</pre>
<a href="index.html">Core OS Index</a>
<p>
This is part of the Tribu System Documentation.
Copyright (C) 2020
Tribu Team.
See the file <a href="../fdl-1.3-standalone.html">Gnu Free Documentation License</a>
for copying conditions.</p>
</body>
</html>
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