linux中关于socket通讯获取本地的源端口号的实现方法(2)-木庄网络博客

2022-05-31 17:10:00 PHP中文网运维百度已收录

终端1：编译及运行

$ g++ source_port.cpp
$ ./a.out www.baidu.com
connect to www.baidu.com success.
local port: 39702

终端2：通过tcpdump抓包验证

$ sudo tcpdump host www.baidu.com -v
tcpdump: listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes
18:38:32.381448 IP (tos 0x0, ttl 64, id 35033, offset 0, flags [DF], proto TCP (6), length 60)
icentos.39702 > 220.181.111.188.http: Flags [S], cksum 0x8cd2 (incorrect -> 0x596a), seq 2381397554, win 29200, options [mss 1460,sackOK,TS val 3513497323 ecr 0,nop,wscale 7], length 0
18:38:32.425904 IP (tos 0x0, ttl 55, id 35033, offset 0, flags [DF], proto TCP (6), length 60)
220.181.111.188.http > icentos.39702: Flags [S.], cksum 0xc315 (correct), seq 3561856904, ack 2381397555, win 8192, options [mss 1424,sackOK,nop,nop,nop,nop,nop,nop,nop,nop,nop,nop,nop,wscale 5], length 0
18:38:32.425930 IP (tos 0x0, ttl 64, id 35034, offset 0, flags [DF], proto TCP (6), length 40)