Linux机器网络检查

查看DNS file:

dian@TestLRSSnapshot:~$ cat /etc/resolv.conf # This file is managed by man:systemd-resolved(8). Do not edit. # # This is a dynamic resolv.conf file for connecting local clients to the # internal DNS stub resolver of systemd-resolved. This file lists all # configured search domains. # # Run "systemd-resolve --status" to see details about the uplink DNS servers # currently in use. # # Third party programs must not access this file directly, but only through the # symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a different way, # replace this symlink by a static file or a different symlink. # # See man:systemd-resolved.service(8) for details about the supported modes of # operation for /etc/resolv.conf. nameserver 127.0.0.53 options edns0 search 4baqgnrc2zverab0oks4co0vjd.ix.internal.cloudapp.net

用Nping测试连接

需要先下载nmap:

sudo apt install nmap

Nping

dian@TestLRSSnapshot:~$ nping login.microsoftonline.com -p 443 Starting Nping 0.7.60 ( Nping — Network packet generation tool & ping utility ) at 2023-07-05 04:19 UTC SENT (0.0050s) Starting TCP Handshake > login.microsoftonline.com:443 (20.190.148.164:443) RCVD (0.0725s) Handshake with login.microsoftonline.com:443 (20.190.148.164:443) completed SENT (1.0078s) Starting TCP Handshake > login.microsoftonline.com:443 (20.190.148.164:443) RCVD (1.0742s) Handshake with login.microsoftonline.com:443 (20.190.148.164:443) completed SENT (2.0104s) Starting TCP Handshake > login.microsoftonline.com:443 (20.190.148.164:443) RCVD (2.0769s) Handshake with login.microsoftonline.com:443 (20.190.148.164:443) completed SENT (3.0131s) Starting TCP Handshake > login.microsoftonline.com:443 (20.190.148.164:443) RCVD (3.0797s) Handshake with login.microsoftonline.com:443 (20.190.148.164:443) completed SENT (4.0159s) Starting TCP Handshake > login.microsoftonline.com:443 (20.190.148.164:443) RCVD (4.0822s) Handshake with login.microsoftonline.com:443 (20.190.148.164:443) completed Max rtt: 67.511ms | Min rtt: 66.360ms | Avg rtt: 66.668ms TCP connection attempts: 5 | Successful connections: 5 | Failed: 0 (0.00%) Nping done: 1 IP address pinged in 4.08 seconds dian@TestLRSSnapshot:~$

Route table in Linux

netstat -rn

dian@TestLRSSnapshot:~$ netstat -rn Kernel IP routing table Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface 0.0.0.0         10.2.0.1        0.0.0.0         UG        0 0          0 eth0 10.2.0.0        0.0.0.0         255.255.255.0   U         0 0          0 eth0 168.63.129.16   10.2.0.1        255.255.255.255 UGH       0 0          0 eth0 169.254.169.254 10.2.0.1        255.255.255.255 UGH       0 0          0 eth0 dian@TestLRSSnapshot:~$

Listening port:

-n -> numeric value (do not resolve service names).

-t -> TCP sockets.

-u -> UDP sockets.

-p -> Processes.

-l -> Listening

dian@TestLRSSnapshot:~$ netstat -ntplu (Not all processes could be identified, non-owned process info  will not be shown, you would have to be root to see it all.) Active Internet connections (only servers) Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name tcp        0      0 127.0.0.53:53           0.0.0.0:*               LISTEN      - tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      - tcp        0      0 0.0.0.0:25324           0.0.0.0:*               LISTEN      - tcp6       0      0 :::22                   :::*                    LISTEN      - udp        0      0 127.0.0.53:53           0.0.0.0:*                           - udp        0      0 10.2.0.4:68             0.0.0.0:*                           - udp        0      0 127.0.0.1:25224         0.0.0.0:*                           -

TCP traceroute

Need to install it firstly: sudo apt install traceroute

dian@TestLRSSnapshot:~$ sudo traceroute -T 40.126.16.166 traceroute to 40.126.16.166 (40.126.16.166), 30 hops max, 60 byte packets  1  * * *  2  * * *  3  * * *  4  * * *  5  * * *  6  * * *  7  * * *  8  * * *  9  * * * 10  * * * 11  * * * 12  * * * 13  * * * 14  * * * 15  * * * 16  * * * 17  * * * 18  * * * 19  * * * 20  * * * 21  * * * 22  * * * 23  40.126.16.166 (40.126.16.166)  65.304 ms *  65.508 ms

NC测连接

dian@TestLRSSnapshot:~$ nc -zv 40.126.16.166 443 Connection to 40.126.16.166 443 port [tcp/https] succeeded!