協議：ICMP、TCP、UDP、http、DNS
ICMP
ping ip/domain
tracert ip/domain
ping www.baidu.com # ICMP
tracert baidu.com # ICMP
TCP/UDP
telnet ip port
nc -zv ip port
nc -zuv ip port
telnet 192.168.1.108 22 # TCP
nc -zv 192.168.1.108 80 # TCP
nc -zuv 192.168.1.108 80 # UDP
HTTP/HTTPS
curl ip or domain
curl http://www.baidu.com # HTTP
curl https://www.baidu.com # HTTPS
Linux: wget curl
Windows: certutil powershell bitsadmin regsrv....
DNS
linux：
dig @8.8.8.8 www.baidu.com #DNS
windows：
nslookup www.baidu.com 8.8.8.8 #DNS