深入网络操作命令

nslookup

# 可以查询域名指定类型的解析记录
nslookup www.baidu.com
# 出现解析不了域名的情况
修改/etc/resolv.conf文件，添加dns解析服务器

nmap

# 扫描端口开放情况
nmap www.baidu.com

strace

# 跟踪命令的调用情况，显示socket连接和open哪些配置文件
[root@VM-4-3-centos ~]# strace -e open,connect,socket nslookup www.baidu.com
open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
open("/lib64/libdns.so.1102", O_RDONLY|O_CLOEXEC) = 3
open("/lib64/liblwres.so.160", O_RDONLY|O_CLOEXEC) = 3
open("/lib64/libbind9.so.160", O_RDONLY|O_CLOEXEC) = 3
open("/lib64/libisccfg.so.160", O_RDONLY|O_CLOEXEC) = 3
open("/lib64/libisc.so.169", O_RDONLY|O_CLOEXEC) = 3
open("/lib64/libgssapi_krb5.so.2", O_RDONLY|O_CLOEXEC) = 3
open("/lib64/libkrb5.so.3", O_RDONLY|O_CLOEXEC) = 3
open("/lib64/libk5crypto.so.3", O_RDONLY|O_CLOEXEC) = 3
open("/lib64/libcom_err.so.2", O_RDONLY|O_CLOEXEC) = 3
open("/lib64/libcrypto.so.10", O_RDONLY|O_CLOEXEC) = 3
open("/lib64/libidn.so.11", O_RDONLY|O_CLOEXEC) = 3
open("/lib64/libcap.so.2", O_RDONLY|O_CLOEXEC) = 3
open("/lib64/libpthread.so.0", O_RDONLY|O_CLOEXEC) = 3
open("/lib64/libGeoIP.so.1", O_RDONLY|O_CLOEXEC) = 3
open("/lib64/libxml2.so.2", O_RDONLY|O_CLOEXEC) = 3
open("/lib64/libz.so.1", O_RDONLY|O_CLOEXEC) = 3
open("/lib64/libm.so.6", O_RDONLY|O_CLOEXEC) = 3
open("/lib64/libdl.so.2", O_RDONLY|O_CLOEXEC) = 3
open("/lib64/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
open("/lib64/libkrb5support.so.0", O_RDONLY|O_CLOEXEC) = 3
open("/lib64/libkeyutils.so.1", O_RDONLY|O_CLOEXEC) = 3
open("/lib64/libresolv.so.2", O_RDONLY|O_CLOEXEC) = 3
open("/lib64/libattr.so.1", O_RDONLY|O_CLOEXEC) = 3
open("/lib64/liblzma.so.5", O_RDONLY|O_CLOEXEC) = 3
open("/lib64/libselinux.so.1", O_RDONLY|O_CLOEXEC) = 3
open("/lib64/libpcre.so.1", O_RDONLY|O_CLOEXEC) = 3
open("/proc/filesystems", O_RDONLY)     = 3
open("/etc/pki/tls/legacy-settings", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en_US.UTF-8/libdns.cat", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en_US.UTF-8/LC_MESSAGES/libdns.cat", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en/libdns.cat", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en/LC_MESSAGES/libdns.cat", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en_US.UTF-8/libisc.cat", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en_US.UTF-8/LC_MESSAGES/libisc.cat", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en/libisc.cat", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en/LC_MESSAGES/libisc.cat", O_RDONLY) = -1 ENOENT (No such file or directory)
socket(AF_INET, SOCK_STREAM, IPPROTO_IP) = 3
socket(AF_INET6, SOCK_STREAM, IPPROTO_IP) = 3
socket(AF_UNIX, SOCK_STREAM, 0)         = 3
open("/proc/self/task/14433/comm", O_RDWR) = 3
open("/proc/self/task/14434/comm", O_RDWR) = 3
open("/proc/self/task/14435/comm", O_RDWR) = 6
open("/usr/share/locale/en_US.UTF-8/libdst.cat", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en_US.UTF-8/LC_MESSAGES/libdst.cat", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en/libdst.cat", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en/LC_MESSAGES/libdst.cat", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/etc/pki/tls/openssl.cnf", O_RDONLY) = 6
open("/etc/resolv.conf", O_RDONLY)      = 6
open("/usr/lib/locale/locale-archive", O_RDONLY|O_CLOEXEC) = 6
Server:		183.60.83.19
Address:	183.60.83.19#53

Non-authoritative answer:
www.baidu.com	canonical name = www.a.shifen.com.
Name:	www.a.shifen.com
Address: 153.3.238.110
Name:	www.a.shifen.com
Address: 153.3.238.102

traceroute

[root@VM-4-3-centos ~]# traceroute www.baidu.com
traceroute to www.baidu.com (153.3.238.102), 30 hops max, 60 byte packets
 1  * * *
 2  * * *
 3  * * *
 4  10.200.66.125 (10.200.66.125)  3.569 ms 10.200.66.81 (10.200.66.81)  2.604 ms 10.200.66.89 (10.200.66.89)  3.488 ms
 5  10.162.5.110 (10.162.5.110)  1.614 ms 220.196.197.162 (220.196.197.162)  2.658 ms 10.162.5.110 (10.162.5.110)  1.653 ms
 6  220.196.197.161 (220.196.197.161)  3.234 ms  3.014 ms 220.196.197.169 (220.196.197.169)  3.189 ms
 7  211.95.32.109 (211.95.32.109)  3.481 ms 211.95.32.69 (211.95.32.69)  3.241 ms 211.95.32.125 (211.95.32.125)  5.259 ms
 8  219.158.17.18 (219.158.17.18)  9.426 ms  9.373 ms  10.216 ms
 9  153.3.228.130 (153.3.228.130)  8.300 ms  8.186 ms  8.567 ms
10  153.37.96.242 (153.37.96.242)  14.538 ms  12.000 ms  11.995 ms
11  182.61.255.184 (182.61.255.184)  9.254 ms 182.61.255.194 (182.61.255.194)  9.369 ms 182.61.255.186 (182.61.255.186)  9.258 ms
12  182.61.255.171 (182.61.255.171)  11.197 ms  11.275 ms 182.61.255.167 (182.61.255.167)  9.293 ms
13  * * *
14  * * *
15  * * *
16  * * *
17  * * *
18  * * *
19  * * *
20  * * *
21  * * *
22  * * *
23  * * *
24  * * *
25  * * *
26  * * *
27  * * *
28  * * *
29  * * *
30  * * *

mtr

# 快速的查看路由情况，一般看最后两个节点
[root@VM-4-3-centos ~]# mtr www.baidu.com

lsof

# 快速查看进程打开了哪些文件
[root@VM-4-3-centos ~]# lsof |grep nginx|grep log
nginx     27660                 root    2w      REG              253,1      3550    1186589 /var/log/nginx/error.log
nginx     27660                 root    4w      REG              253,1      3550    1186589 /var/log/nginx/error.log
nginx     27660                 root    5w      REG              253,1      9437    1186588 /var/log/nginx/access.log
nginx     27661                nginx    2w      REG              253,1      3550    1186589 /var/log/nginx/error.log
nginx     27661                nginx    4w      REG              253,1      3550    1186589 /var/log/nginx/error.log
nginx     27661                nginx    5w      REG              253,1      9437    1186588 /var/log/nginx/access.log
nginx     27662                nginx    2w      REG              253,1      3550    1186589 /var/log/nginx/error.log
nginx     27662                nginx    4w      REG              253,1      3550    1186589 /var/log/nginx/error.log
nginx     27662                nginx    5w      REG              253,1      9437    1186588 /var/log/nginx/access.log

# 查看网络连接
[root@VM-4-3-centos ~]# lsof -i:80
COMMAND   PID  USER   FD   TYPE   DEVICE SIZE/OFF NODE NAME
nginx   27660  root    6u  IPv4 62447989      0t0  TCP *:http (LISTEN)
nginx   27661 nginx    6u  IPv4 62447989      0t0  TCP *:http (LISTEN)
nginx   27662 nginx    6u  IPv4 62447989      0t0  TCP *:http (LISTEN)