Operation of the network can be handle with init scripts or with network manager;
Choose wireless (wlan), cable network (net) or network manager in /etc/rc.conf to handle configuration of the network at startup, example using network manager;
#
# /etc/rc.conf: system configuration
#
FONT=default
KEYMAP=dvorak
TIMEZONE="Europe/Lisbon"
HOSTNAME=machine
SYSLOG=sysklogd
SERVICES=(lo iptables networkmanager crond)
# End of file
If is first boot after install configure iptables and one of above described scripts then proceed to update system.
This example will use Chaos Computer Club server, edit /etc/resolv.conf and make it immutable;
# /etc/resolv.conf.head can replace this line
nameserver 2.2.73.91.35
# /etc/resolv.conf.tail can replace this line
# chattr +i /etc/resolv.conf
Current example of /etc/rc.d/net;
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)
Other IP class that can used for private network;
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)
Manual configuring like net script;
# DEV=enp8s0
# ADDR=192.168.1.9
# MASK=24
# GW=192.168.1.254
# 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}
For more information about firewall systems read arch wiki iptables and nftables.
Diagram of a package route throw iptables;
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
Command line usage;
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]
Targets, can be a user defined chain;
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.
Target Extensions
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.
Commands
-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
Parameters
-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
See current rules and packets counts;
# iptables -L -n -v | less
Scripts help to setup iptables rules so they can be saved using iptables-save and later restored using iptables-restore utilities. Init script /etc/rc.d/iptables 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.
Setup init script and rules;
# 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
Change /etc/rc.conf and add iptables;
SERVICES=(iptables lo net crond)
Change /etc/rc.d/iptables and define type; server, bridge or open.
Adjust /etc/iptables/ipt-conf.sh with your network configuration, and adjust /etc/iptables/ipt-server.sh, /etc/iptables/ipt-bridge.sh, /etc/iptables/ipt-open.sh according with host necessities.
When is everything configured run script to load the rules and save them on /etc/iptables. Example for bridge setup;
# cd /etc/iptables
# bash ipt-bridge.sh
From now on use /etc/rc.d/iptables to start and stop.
For more information about bridges read bridges with iptables. Script /etc/rc.d/blan creates br0 bridge interface with 10.0.0.1 ip. Number of tap interfaces created and attached depends on number of cpu cores available. Ethernet interface is added to the bridge. Edit /etc/rc.conf to setup interfaces at startup;
#
# /etc/rc.conf: system configuration
#
FONT=default
KEYMAP=dvorak
TIMEZONE="Europe/Lisbon"
HOSTNAME=machine
SYSLOG=sysklogd
SERVICES=(lo iptables wlan blan crond)
# End of file
Change iptables init script /etc/rc.d/iptables and set TYPE to bridge, /etc/iptables/bridge.v4. Now change ipt-conf.sh and ipt-bridge.sh with your network configuration and run;
# bash ipt-bridge.sh
There is more information on Wiki Wifi Start Scripts and see /etc/rc.d/wlan. Manual or first time configuration;
# ip link
# iwlist wlp2s0 scan
# iwconfig wlp2s0 essid NAME key s:ABCDE12345
Configure wpa supplicant edit;
# vim /etc/wpa_supplicant.conf
ctrl_interface=/var/run/wpa_supplicant
update_config=1
fast_reauth=1
ap_scan=1
# wpa_passphrase <ssid> <password> >> /etc/wpa_supplicant.conf
Now start wpa_supplicant with:
# wpa_supplicant -B -i wlp2s0 -c /etc/wpa_supplicant.conf
Successfully initialized wpa_supplicant
Use /etc/rc.d/wlan init script to auto load wpa configuration and dhcp client.
# wpa_cli
> status
> add_network
3
> set_network 3 ssid "Crux-Network"
OK
> set_network 3 psk "uber-secret-pass"
OK
> enable_network 3
OK
> list_networks
> select_network 3
> save_config
Wifi status;
$ nmcli radio wifi
$ nmcli radio wifi on
List wifi networks;
$ nmcli device wifi rescan
$ nmcli device wifi list
Connect to a wifi network;
$ nmcli device wifi connect "network name" password "network password"
Edit and save network configuration;
$ nmcli connection edit "network name"
nmcli> save persistent
To configure a sub-domain from afraid.org, generate cron job to update ip every 5 minutes, check about dynamic interface. To run as system cron job add as root and remove path line from example;
# crontab -e
Replace KEY and domain_name with correct one;
4,9,14,19,24,29,34,39,44,49,54,59 * * * * sleep 22 ; wget --no-check-certificate -O - https://freedns.afraid.org/dynamic/update.php?[KEY]= >> /var/log/freedns_domain_name.log 2>&1 &
GNU/Linux Index
This is part of the LeetIO System Documentation. Copyright (C) 2021 LeetIO Team. See the file Gnu Free Documentation License for copying conditions.