最近阿里云ECS貌似有点不稳定啊，今天踩了两个坑。
一、ssh远程访问有问题
我xshell远程访问时断时续，后来干脆登不上去了，提示错误：
Socket error Event: 32 Error: 10053. Disconnected from remote host
关键我在同一台电脑上使用阿里云提供的网页远程功能却可以远程访问。
网上试了一些方法都没效果，比如有
说IP地址冲突的，修改为固定IP；有说key的权限问题的，重新生成key，并配置权限；有说IP被阿里禁了，怎么可能，web端访问正常；有说没有在ECS安全组里配置端口的，之前都配置了；有说是xshell的问题，换了个putty还是不行；最后连重启大法都试了。无奈，吃了个午饭回来居然神奇般地能远程访问了。到现在我也没弄明白是为什么，真是佛系，希望有踏过类似坑的大佬帮忙解答。
二、更新系统后，apt源出问题
今天用xshell更新了下阿里云ECS系统，提示有更新，强迫症的我就更新了，更新完之后apt的源居然出问题了，
apt-get clean apt-get update aptitude update 都用不了了
下面是更新之后的apt源： /etc/apt/sources.list
1 ## Note, this file is written by cloud-init on first boot of an instance
2 ## modifications made here will not survive a re-bundle.
3 ## if you wish to make changes you can:
4 ## a.) add 'apt_preserve_sources_list: true' to /etc/cloud/cloud.cfg
5 ## or do the same in user-data
6 ## b.) add sources in /etc/apt/sources.list.d
7 ## c.) make changes to template file /etc/cloud/templates/sources.list.tmpl
8
9 # See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
10 # newer versions of the distribution.
11
12 deb http://mirrors.cloud.aliyun.com/ubuntu/ bionic main
13 deb-src http://mirrors.cloud.aliyun.com/ubuntu/ bionic main
14
15 ## Major bug fix updates produced after the final release of the
16 ## distribution.
17 deb http://mirrors.cloud.aliyuncs.com/ubuntu/ bionic-updates main
18 deb-src http://mirrors.cloud.aliyuncs.com/ubuntu/ bionic-updates main
19
20 ## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
21 ## team. Also, please note that software in universe WILL NOT receive any
22 ## review or updates from the Ubuntu security team.
23 deb http://mirrors.cloud.aliyuncs.com/ubuntu/ bionic universe
24 deb-src http://mirrors.cloud.aliyuncs.com/ubuntu/ bionic universe
25 deb http://mirrors.cloud.aliyuncs.com/ubuntu/ bionic-updates universe
26 deb-src http://mirrors.cloud.aliyuncs.com/ubuntu/ bionic-updates universe
27
28 ## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
29 ## team, and may not be under a free licence. Please satisfy yourself as to
30 ## your rights to use the software. Also, please note that software in
31 ## multiverse WILL NOT receive any review or updates from the Ubuntu
32 ## security team.
33 deb http://mirrors.cloud.aliyuncs.com/ubuntu/ xenial multiverse
34 deb-src http://mirrors.cloud.aliyuncs.com/ubuntu/ xenial multiverse
35 deb http://mirrors.cloud.aliyuncs.com/ubuntu/ xenial-updates multiverse
36 deb-src http://mirrors.cloud.aliyuncs.com/ubuntu/ xenial-updates multiverse
37
38 ## Uncomment the following two lines to add software from the 'backports'
39 ## repository.
40 ## N.B. software from this repository may not have been tested as
41 ## extensively as that contained in the main release, although it includes
42 ## newer versions of some applications which may provide useful features.
43 ## Also, please note that software in backports WILL NOT receive any review
44 ## or updates from the Ubuntu security team.
45 deb http://mirrors.cloud.aliyuncs.com/ubuntu/ xenial-backports main restricted universe multiverse
46 deb-src http://mirrors.cloud.aliyuncs.com/ubuntu/ xenial-backports main restricted universe multiverse
47
48 ## Uncomment the following two lines to add software from Canonical's
49 ## 'partner' repository.
50 ## This software is not part of Ubuntu, but is offered by Canonical and the
51 ## respective vendors as a service to Ubuntu users.
52 # deb http://archive.canonical.com/ubuntu xenial partner
53 # deb-src http://archive.canonical.com/ubuntu xenial partner
54
55 #deb http://mirrors.cloud.aliyun.com/ubuntu bionic-security main
56 #deb-src http://mirrors.cloud.aliyun.com/ubuntu bionic-security main
57 #deb http://mirrors.cloud.aliyun.com/ubuntu bionic-security universe
58 #deb-src http://mirrors.cloud.aliyun.com/ubuntu bionic-security universe
59 # deb http://mirrors.cloud.aliyuncs.com/ubuntu xenial-security multiverse
60 # deb-src http://mirrors.cloud.aliyuncs.com/ubuntu xenial-security multiverse
搞了半天，阿里云的apt源居然打不开 http://mirrors.cloud.aliyun.com/ubuntu/
最后换了别的源搞定，这里推荐几个比较好用的吧：
清华大学的源 https://mirrors.tuna.tsinghua.edu.cn/help/ubuntu/
中科大的源 http://mirrors.ustc.edu.cn/
完毕！