Linux Networking
nm-connection-editor
/etc/init.d/network-manager restart
https://access.redhat.com/sites/default/files/attachments/rh_ip_command_cheatsheet_1214_jcs_print.pdf
ls -l /sys/class/net/ # E.g.: ens3 -> ../../devices/pci0000:00/0000:00:03.0/virtio0/net/ens3
ip addr show dev eth1
ifconfig ens7 10.99.0.10/16 up
ip addr add 192.168.6.13/24 dev eth0 && ip link set eth0 up
ip addr flush dev eth0
ifconfig eth0 0.0.0.0 0.0.0.0 && dhclient
ip route add default via 192.168.1.1
ip route show table all
auto enp1s0
iface enp1s0 inet dhcp
network:
version: 2
ethernets:
enp1s0: {}
enp2s0: {}
enp3s0: {}
enp4s0: {}
enp5s0: {}
enp6s0:
dhcp4: yes
bridges:
br0:
interfaces: [enp1s0,enp2s0]
dhcp4: yes
br1: {}
ovs-br0:
openvswitch: {} #
dhcp4: yes
vlans:
vlan.10:
id: 10
link: enp4s0
dhcp4: yes
setup ovs manually
netplan try # if error, run: netplan generate
# netstat -lntup | grep 8888
tcp 0 0 0.0.0.0:8888 0.0.0.0:* LISTEN 5119/python
tcp6 0 0 :::8888 :::* LISTEN 5119/python
# ss -lntup | grep 8888
tcp LISTEN 0 128 0.0.0.0:8888 0.0.0.0:* users:(("jupyter-noteboo",pid=5119,fd=7))
tcp LISTEN 0 128 [::]:8888 [::]:* users:(("jupyter-noteboo",pid=5119,fd=6))
tcpdump -i any port 27017
nmap -sV -p6379 127.0.0.1
https://en.wikipedia.org/wiki/Netlink
https://github.com/shemminger/iproute2/blob/master/misc/ss.c
ip tuntap add mode tap dev tap1
tap1: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1000
link/ether a2:05:e8:7f:d9:e8 brd ff:ff:ff:ff:ff:ff
ip tuntap add mode tun dev tun1
tun1: <POINTOPOINT,MULTICAST,NOARP> mtu 1500 qdisc noop state DOWN group default qlen 500
link/none
ethtool -k ens3 | grep offload # list Features
ethtool -K ens3 gro off gso off tso off # set tcp-segmentation-offload, generic-segmentation/receive-offload
echo "net.ipv6.conf.all.disable_ipv6=1" >> /etc/sysctl.conf
sysctl -p
- https://wiki.nftables.org/wiki-nftables/index.php/Main_Page
- https://wiki.nftables.org/wiki-nftables/index.php/Moving_from_iptables_to_nftables
- https://openwrt.org/docs/guide-user/firewall/misc/nftables
iptables -t nat -L # filter(default), nat, mangle, raw and security
iptables -t nat -F ... # empty chain rules
iptables -t nat -X ... # delete empty chain
iptables -t nat -L -n -x -v # --numeric IP/Port --exact packet and byte counters --verbose
iptables -L --line-numbers
iptables -D INPUT 2
iptables-save
iptables -I INPUT -i docker0 -j ACCEPT
iptables -I INPUT -s localhost -j ACCEPT
iptables -A INPUT --dport 81 -j DROP
iptables -A INPUT -p tcp -m multiport --dport 3306,6379 -j DROP
iptables -A INPUT -p udp --dport 161 -j ACCEPT
http://www.netfilter.org/documentation/HOWTO//NAT-HOWTO-3.html
_____ _____
/ \ / \
PREROUTING -->[Routing ]----------------->POSTROUTING----->
\D-NAT/ [Decision] \S-NAT/
| ^
| |
--------> Local Process ------
Masquerading is a specialized form of SNAT
Port forwarding, load sharing, and transparent proxying are all forms of DNAT.
http://www.netfilter.org/documentation/HOWTO//NAT-HOWTO-6.html
http://ipset.netfilter.org/iptables-extensions.man.html
http://backreference.org/2010/06/11/iptables-debugging/
modprobe nf_log_ipv4
sysctl net.netfilter.nf_log.2=nf_log_ipv4
iptables -t raw -A OUTPUT -p icmp -j TRACE
iptables -t raw -A PREROUTING -p icmp -j TRACE
vi /var/log/kern.log
http://www.microhowto.info/troubleshooting/troubleshooting_iptables.html
iptables_log_INPUT_DROP() {
iptables -N LOGGING
iptables -A INPUT -j LOGGING
iptables -A LOGGING -m limit --limit 2/min -j LOG --log-prefix "IPTables-Dropped: " --log-level 4
iptables -A LOGGING -j DROP
}
iptables -t nat -N TP
iptables -t nat -I TP -p tcp --dport 4433 -j RETURN # bypass Port
# https://tools.ietf.org/html/rfc5735#page-6
iptables -t nat -A TP -d 0.0.0.0/8 -j RETURN
iptables -t nat -A TP -d 10.0.0.0/8 -j RETURN
iptables -t nat -A TP -d 127.0.0.0/8 -j RETURN
iptables -t nat -A TP -d 169.254.0.0/16 -j RETURN
iptables -t nat -A TP -d 172.16.0.0/12 -j RETURN
iptables -t nat -A TP -d 192.168.0.0/16 -j RETURN
iptables -t nat -A TP -d 224.0.0.0/4 -j RETURN
iptables -t nat -A TP -d 240.0.0.0/4 -j RETURN
# Anything else should be redirected to Dokodemo-door's local port
iptables -t nat -A TP -p tcp -j REDIRECT --to-ports 20088
iptables -t nat -I OUTPUT -p tcp -j TP
iptables -t nat -I PREROUTING -p tcp -j TP
# Add any UDP rules
iptables -t mangle -N TP
iptables -t mangle -A TP -p udp --dport 53 -j TPROXY --on-port 20088 --tproxy-mark 0x01/0x01
iptables -t mangle -A PREROUTING -j TP
iptables -t mangle -N TP_MARK
iptables -t mangle -A TP_MARK -p udp --dport 53 -j MARK --set-mark 1
iptables -t mangle -A OUTPUT -j TP_MARK
ip route add local default dev lo table 100
ip rule add fwmark 1 lookup 100
ip rule del fwmark 1 lookup 100 # disable UDP
firewall-cmd --permanent --zone=public \
--add-rich-rule="rule family="ipv4" \
source address="1.2.3.4/32" \
port protocol="tcp" port="4567" accept"
firewall-cmd --zone=public --add-port=4433/tcp --permanent
firewall-cmd --zone=public --add-port=4433/udp--permanent
firewall-cmd --reload
firewall-cmd --list-all
service firewalld stop
sudo ufw allow 11200:11299/tcp
sudo ufw status verbose
sudo ufw disable
Priority: 0, Selector: match anything, Action: lookup routing
table local (ID 255). The local table is a special routing
table containing high priority control routes for local and
broadcast addresses.
Priority: 32766, Selector: match anything, Action: lookup
routing table main (ID 254). The main table is the normal
routing table containing all non-policy routes. This rule may
be deleted and/or overridden with other ones by the
administrator.
Priority: 32767, Selector: match anything, Action: lookup
routing table default (ID 253). The default table is empty.
It is reserved for some post-processing if no previous default
rules selected the packet. This rule may also be deleted.
# cat /etc/iproute2/rt_tables
#
# reserved values
#
255 local
254 main
253 default
0 unspec
#
# local
#
#1 inr.ruhep
http://events.linuxfoundation.org/sites/events/files/slides/Linux_traffic_control.pdf
http://kb.linuxvirtualserver.org/wiki/IPVS
https://github.com/torvalds/linux/tree/master/net/netfilter/ipvs
IPVS - an advanced layer-4 load balancing solution， NAT/Direct Routing/IP Tunneling
https://docs.cumulusnetworks.com/display/DOCS/Virtual+Routing+and+Forwarding+-+VRF
multiple independent routing tables working simultaneously on the same router or switch Think of this feature as VLAN for layer 3
https://www.kernel.org/doc/Documentation/networking/vrf.txt
/etc/nsswitch.conf
#hosts: files mdns4_minimal [NOTFOUND=return] dns mdns4
hosts: files dns # fix nslookup works but ping not work
https://github.com/jpirko/libteam/wiki/Tutorial
Last modified 4mo ago