Myron's Dev Notes

Networking

private address spaces

10.0.0.0/8      10.0.0.0    – 10.255.255.255
172.16.0.0/12   172.16.0.0  – 172.31.255.255
192.168.0.0/16  192.168.0.0 – 192.168.255.255

curl -v ipv4.icanhazip.com
curl -v -6 ipv6.icanhazip.com

curl

curl -fsSL <url> | bash

populate arp tables

nmap -T5 -n -sn x.x.x.0/24

Vendor lookup from mac-addr

arp -a |cut -d' ' -f4 |grep -v incom|cut -c-8 |sort -u > mac-addrs
for i in $(cat mac-addrs ); do echo $i; curl https://api.macvendors.com/$i; echo; sleep 2; done
# grep and sort by IP
arp -a |awk '{print $4 " " $2}' |tr -d "\(\)" |sort -uk2 -V |grep 'xx:xx:xx'

DNS flush

# apple
sudo killall -HUP mDNSResponder
sudo killall mDNSResponderHelper
sudo dscacheutil -flushcache

tcpdump

# syn/fin
tcpdump -ni en0 'tcp[tcpflags] & (tcp-syn|tcp-fin) != 0'
tcpdump -i eno2 ether host 'xx:xx:xx:xx:xx:xx'
tcpdump -i eno2 ip host \( 1.2.3.4 or  4.3.2.1 \)
tcpdump -n icmp # watch for pings
tcpdump -i eth1 not arp and port 53

routes

sudo route del default
sudo route add default gw 10.182.200.1 eth1
traceroute -n -w 1 10.182.200.100
ip route get to 198.51.100.1 from 192.168.0.2 iif eth0

Connection tests

echo X | telnet -e X 192.168.1.135 3306
nc -v -z -w1 192.168.1.135 3306
nc -vz email-smtp.us-east-1.amazonaws.com 587 # 25, 465

Linux listening Ports

ss -nlt
# which process listening
lsof -ni ':80'

Get my IP

Monitoring tools

MacOS

Virtual Hosts Setup

sudo -i
ifconfig vlan11 create
ifconfig vlan22 create
ifconfig vlan11 vlan 11 vlandev en1
ifconfig vlan22 vlan 22 vlandev en1
ifconfig vlan11 inet 10.10.11.11 netmask 255.255.255.255
ifconfig vlan22 inet 10.10.22.22 netmask 255.255.255.255

ifconfig vlan11 destroy
ifconfig vlan22 destroy


# another way?
sudo ifconfig en0  alias 10.10.11.11/32 up # create
sudo ifconfig en0  alias 10.10.22.22/32 up # create

sudo ifconfig en0 -alias 10.0.11.11/32     # remove
sudo ifconfig en0 -alias 10.0.22.22/32     # remove

Local DNS with dnsmasq

brew install dnsmasq
cp /usr/local/etc/dnsmasq.conf /usr/local/etc/dnsmasq.conf.orig
echo "conf-dir=/usr/local/etc/dnsmasq.d/,*.conf" | tee /usr/local/etc/dnsmasq.conf
cat > /usr/local/etc/dnsmasq.d/mylocal.conf <<EOF
address=/host1.io.local/192.168.20.21
address=/host2.io.local/192.168.20.22
address=/.samplenet.io.local/192.168.20.21
EOF

sudo mkdir -p /etc/resolver

cat > /etc/resolver/io.local <<EOF
nameserver 127.0.0.1
EOF

sudo brew services start dnsmasq

dnsmasq direct test

dig host1.io.local @localhost +short
192.168.20.21
dig anyname.io.local @localhost +short
192.168.20.21

see dns detail

scutil --dns

flush dns

sudo dscacheutil -flushcache
sudo killall -HUP mDNSResponder