获取外网 IP 的方法

Question

ifconfig.me

$ curl ifconfig.me
114.245.180.114

$ curl ifconfig.me/all.json
{"connection":"","ip_addr":"114.245.180.114","lang":"","remote_host":"",
"user_agent":"curl/7.24.0 (x86_64-apple-darwin12.0) libcurl/7.24.0 OpenSSL/0.9.8x zlib/1.2.5",
"charset":"","port":"64364","via":"","forwarded":"","mime":"*/*","keep_alive":"","encoding":""}

ns1.dnspod.net:6666

$ curl ns1.dnspod.net:6666
114.245.180.114

alibaba的Set-Cookie 机制

$ curl http://www.alibaba.com -I
HTTP/1.1 200 OK
Date: Sun, 08 Sep 2013 03:11:48 GMT
Server: Apache
P3P: CP="CAO PSA OUR"
Resin-Trace: ali_resin_trace=nuser=Y
Content-Language: en-US
Vary: Accept-Encoding,User-Agent
Content-Type: text/html;charset=UTF-8
Set-Cookie: ali_apache_id=114.245.180.114.1378609908526.188808.8; \
path=/; domain=.alibaba.com; expires=Wed, 30-Nov-2084 01:01:01 GMT
Set-Cookie: JSESSIONID=127F0EDC9FB6493605DE8BCEDDB6C516; Path=/
Set-Cookie: ali_apache_track=; Domain=.alibaba.com; Expires=Fri, 26-Sep-2081 06:25:55 GMT; Path=/
Set-Cookie: ali_apache_tracktmp=; Domain=.alibaba.com; Path=/
Set-Cookie: xman_us_f=x_l=1; Domain=.alibaba.com; \
Expires=Fri, 26-Sep-2081 06:25:55 GMT; Path=/
Set-Cookie: acs_usuc_t=acs_rt=f82659d54cbb4c8d9967be359a9b6de1; Domain=.alibaba.com; Path=/
Set-Cookie: xman_t=/Ob3a3y7rXnRNLDVGdVrGT13KmY5uwewJx22h+dDMOO6yNkLr7CyrqOxzd57qsqe; Domain=.alibaba.com; Path=/; HttpOnly
Set-Cookie: acs_t=qphCAArZ3JQXnavkXLfwari9kPcSWWq3zP5Rj5aYr+qiePCS2dwV4olPDJ3JWOlj; Domain=.alibaba.com; Path=/; HttpOnly
Set-Cookie: xman_f=JQpTDcnKW5ZSD359Hxzldl/1bVVJWFHw6dqPkwxqaAXmEoKY/LQ6/OL5GBqTUBnSsng0fzQO5ZteGWMvIHB0AAICCvVffk5Mkc4vKSZEcpizKeaxJrq/kw==; \
Domain=.alibaba.com; Expires=Fri, 26-Sep-2081 06:25:55 GMT; Path=/; HttpOnly

$ curl -I -s http://www.alibaba.com | sed -nE \
's/Set-Cookie: ali_apache_id=([0-9]+.[0-9]+.[0-9]+.[0-9]+).*/\1/gp'
123.66.179.233