1、curl
（1）curl -v ip:port
[root@localhost ~]# curl -v 192.168.120.15:37777
* About to connect() to 192.168.120.15 port 37777 (#0)
* Trying 192.168.120.15...
* Connected to 192.168.120.15 (192.168.120.15) port 37777 (#0)
> GET / HTTP/1.1
> User-Agent: curl/7.29.0
> Host: 192.168.120.15:37777
> Accept: */*
>（2）curl -kv https://ip:port
[root@localhost ~]# curl -kv https://192.168.12.15:3789
* About to connect() to 192.168.12.15 port 3789 (#0)
* Trying 192.168.12.15...
* Connected to 192.168.12.15 (192.168.12.15) port 3789 (#0)
* Initializing NSS with certpath: sql:/etc/pki/nssdb
* skipping SSL peer certificate verification
* SSL connection using TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
* Server certificate:
* subject: CN=cn.com.ca.d6.agent
* start date: 4月 26 03:51:05 2021 GMT
* expire date: 4月 26 03:51:05 2041 GMT
* common name: cn.com.ca.d6.agent
* issuer: CN=cn.com.ca.d6.agent
> GET / HTTP/1.1
> User-Agent: curl/7.29.0
> Host: 192.168.12.15:3789
> Accept: */*
>
< HTTP/1.1 404
< Connection:close
< Content-Length:22
< Content-Type:text/html
< X-Frame-Options:sameorigin
<
* Closing connection 0
<html>not found</html>2、nc
（1）nc -nv ip port
[root@localhost ~]# nc -nv 192.168.12.15 3789
Ncat: Version 7.50 ( https://nmap.org/ncat )
Ncat: Connected to 192.168.12.15:3789.
^C
（2）nc -nvv ip port
[root@localhost ~]# nc -nvv 192.168.12.15 3789
Ncat: Version 7.50 ( https://nmap.org/ncat )
NCAT DEBUG: Using system default trusted CA certificates and those in /usr/share/ncat/ca-bundle.crt.
NCAT DEBUG: Unable to load trusted CA certificates from /usr/share/ncat/ca-bundle.crt: error:02001002:system library:fopen:No such file or directory
libnsock nsi_new2(): nsi_new (IOD #1)
libnsock nsock_connect_tcp(): TCP connection requested to 192.168.12.15:3789 (IOD #1) EID 8
libnsock nsock_trace_handler_callback(): Callback: CONNECT SUCCESS for EID 8 [192.168.12.15:3789]
Ncat: Connected to 192.168.12.15:3789.
libnsock nsi_new2(): nsi_new (IOD #2)
libnsock nsock_read(): Read request from IOD #1 [192.168.12.15:3789] (timeout: -1ms) EID 18
libnsock nsock_readbytes(): Read request for 0 bytes from IOD #2 [peer unspecified] EID 26
^C3、ssh
（1）ssh -v -p port username@ip // username任意
[root@localhost ~]# ssh -v -p 3789 root@192.168.12.15
OpenSSH_7.4p1, OpenSSL 1.0.2k-fips 26 Jan 2017
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 58: Applying options for *
debug1: Connecting to 192.168.120.15 [192.168.12.15] port 3789.
debug1: Connection established.
debug1: permanently_set_uid: 0/0
debug1: identity file /root/.ssh/id_rsa type 1
debug1: key_load_public: No such file or directory
debug1: identity file /root/.ssh/id_rsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /root/.ssh/id_dsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /root/.ssh/id_dsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /root/.ssh/id_ecdsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /root/.ssh/id_ecdsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /root/.ssh/id_ed25519 type -1
debug1: key_load_public: No such file or directory
debug1: identity file /root/.ssh/id_ed25519-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_7.4
^C4、wget
（1）wget ip:port
[root@localhost ~]# wget 192.168.12.15:3789
--2023-03-25 17:05:20-- http://192.168.12.15:3789/
正在连接 192.168.120.15:37777... 已连接。
已发出 HTTP 请求，正在等待回应... ^C5、telnet
（1）telnet ip port
[root@localhost ~]# telnet 192.168.12.15 3789
Trying 192.168.12.15...
Connected to 192.168.12.15.
Escape character is '^]'.
^CConnection closed by foreign host.端口通 ！= 业务通
tcp端口通，上面跑的http业务可能不通（代理限制）。
tcp层：nc，ssh，telnet
http层：curl，wget