運維少年系列 python and cisco （1）

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預備知識

本系列文章需要各位具有CCNA/HCNA基礎知識（知道命令怎么敲）

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python

本系列文章需要使用到的python版本為2.7，模塊為paramiko。
為何使用python2.7而不是3.x？因為絕大部分系統都自帶了2.7，就這么簡單~

paramiko模塊功能十分強大，最常使用的就是其SSH登錄的功能，使用paramiko實現了SSH登錄之后，還可以執行命令，實現遠程配置設備。在代碼編寫部分我會向各位簡單的介紹一下每段代碼的作用。

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系列文章說明

系列文章不會很多（預計2-3篇？），畢竟就一個模塊，從簡單到稍微復雜一點，然后從單點到批量，然后到異常處理，大概的路線就是這樣。文章有些地方可能描述的不準確，請大家多多指教。

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python and cisco

1) 拓撲圖

• 使用GNS3做一個簡單的拓撲，將centos橋接GNS3中，使路由器與centos相連。

2) 交換機配置

• 交換機配置ssh，注意密鑰的長度不要使用512，不然登錄會失敗。

R3(config)#hostname?R3
R3(config)#ip?domain?name?yunwsn.com
R3(config)#crypto?key?generate?rsa
The?name?for?the?keys?will?be:?R3.yunwsn.com
Choose?the?size?of?the?key?modulus?in?the?range?of?360?to?2048?for?your
??General?Purpose?Keys.?Choosing?a?key?modulus?greater?than?512?may?take
??a?few?minutes.

How?many?bits?in?the?modulus?[512]:?2048
%?Generating?512?bit?RSA?keys,?keys?will?be?non-exportable...[OK]
*Mar??1?00:11:52.127:?%SSH-5-ENABLED:?SSH?2.0?has?been?enabled
R3(config)#
R2(config)#line?vty?0?10
R2(config-line)#transport?input?ssh
R2(config-line)#login?local
R2(config-line)#exit
R1(config)#username?yunwsn?privilege?15?password?123456
R1(config)#enable?password?123456

3) python配置

• 安裝paramiko

沒有pip的百度安裝一下吧~

[root@yunwei?~]#?pip?install?paramiko
DEPRECATION:?Python?2.7?will?reach?the?end?of?its?life?on?January?1st,?2020.?Please?upgrade?your?Python?as?Python?2.7?won't?be?maintained?after?that?date.?A?future?version?of?pip?will?drop?support?for?Python?2.7.
Collecting?paramiko
??Using?cached?https://files.pythonhosted.org/packages/cf/ae/94e70d49044ccc234bfdba20114fa947d7ba6eb68a2e452d89b920e62227/paramiko-2.4.2-py2.py3-none-any.whl
Requirement?already?satisfied:?cryptography>=1.5?in?/usr/lib64/python2.7/site-packages?(from?paramiko)?(2.6.1)
Requirement?already?satisfied:?pynacl>=1.0.1?in?/usr/lib64/python2.7/site-packages?(from?paramiko)?(1.3.0)
Requirement?already?satisfied:?pyasn1>=0.1.7?in?/usr/lib/python2.7/site-packages?(from?paramiko)?(0.4.5)
Requirement?already?satisfied:?bcrypt>=3.1.3?in?/usr/lib64/python2.7/site-packages?(from?paramiko)?(3.1.6)
Requirement?already?satisfied:?enum34;?python_version?<?"3"?in?/usr/lib/python2.7/site-packages?(from?cryptography>=1.5->paramiko)?(1.1.6)
Requirement?already?satisfied:?asn1crypto>=0.21.0?in?/usr/lib/python2.7/site-packages?(from?cryptography>=1.5->paramiko)?(0.24.0)
Requirement?already?satisfied:?cffi!=1.11.3,>=1.8?in?/usr/lib64/python2.7/site-packages?(from?cryptography>=1.5->paramiko)?(1.12.3)
Requirement?already?satisfied:?six>=1.4.1?in?/usr/lib/python2.7/site-packages?(from?cryptography>=1.5->paramiko)?(1.12.0)
Requirement?already?satisfied:?ipaddress;?python_version?<?"3"?in?/usr/lib/python2.7/site-packages?(from?cryptography>=1.5->paramiko)?(1.0.22)
Requirement?already?satisfied:?pycparser?in?/usr/lib/python2.7/site-packages?(from?cffi!=1.11.3,>=1.8->cryptography>=1.5->paramiko)?(2.19)
Installing?collected?packages:?paramiko
Successfully?installed?paramiko-2.4.2
[root@yunwei?~]#?

• 代碼編寫

#!/usr/bin/env?python
import?paramiko???#?導入paramiko模塊
import?time???????#?導入time模塊，這個后面會用到
host?=?'192.168.108.254'???#?定義主機IP
user?=?'yunwsn'????????????#?定義登錄的用戶名
passwd?=?'123456'??????????#?定義使用的密碼
s?=?paramiko.SSHClient()???#?實例化，啥意思?請看注釋①
s.set_missing_host_key_policy(paramiko.AutoAddPolicy())??#?請看注釋②
s.connect(host,username=user,password=passwd,look_for_keys=False,allow_agent=False)?#?定義登錄的IP、用戶名和密碼
print?'login?success.'??#?登錄成功提示
cmd?=?s.invoke_shell()??#?創建一個交互式的shell，實現多發送條命令
cmd.send("conf?t?\n")???#?發送命令
time.sleep(1)???????????#?睡眠1s，特別重要，注釋③
cmd.send("int?f0/1?\n")
time.sleep(1)
cmd.send("ip?add?1.1.1.2?255.255.255.0?\n")
time.sleep(1)
cmd.send("end?\n")
time.sleep(1)
cmd.send("show?ip?int?bri\n?")
time.sleep(1)
output?=?cmd.recv(65535)??#?接收輸出
print?output??????????????#?打印輸出
cmd.close()???????????????#?關閉交互式shell

• 注釋：

  • ①：實例化可以簡單的理解為，將paramiko.SSHClient類的所有屬性賦予s。就比如，張三的父親是富一代，那么屬性就是有錢，然后…嗯，差不多，實例化之后，s可以使用原先paramiko.SSHClient()下面所有的辦法，其實也可以將其理解為一個別名，給paramiko.SSHClient取個別名叫s

  • ②：在登陸時，有些設備會提示以下內容，需要用戶輸入【yes】才能進行下一步，而使用了這個參數，則不需要輸入yes

????[root@yunwei?cisco]#?ssh?yunwsn@192.168.108.254
????The?authenticity?of?host?'192.168.108.254?(192.168.108.254)'?can't?be?established.
????RSA?key?fingerprint?is?SHA256:FBFOoRUMkKYCyDbpZKkRiuhCbiYuOX8EuHLUMoN0C/M.
????RSA?key?fingerprint?is?MD5:b9:ad:29:24:43:bb:48:8c:58:3e:ce:03:a4:74:e2:cf.
????Are?you?sure?you?want?to?continue?connecting?(yes/no)??

• ③：在我的GNS3中，路由器反應比較慢，比如我輸入了conf t ，他可能過了0.5s才能進入config模式，python的下一條命令int f0/1可能在0.5s的時候就執行了，導致命令執行不成功，所以，我在中間加入了一個睡眠，1s后再執行下個命令，大家在使用的時候可以修改這個時間，使命令執行時間更加合理。

4) 實現效果

[root@yunwei?cisco]#?python?ywsn_p_c_lab1.py?
login?success.

R1#conf?t?
Enter?configuration?commands,?one?per?line.??End?with?CNTL/Z.
R1(config)#int?f0/1?
R1(config-if)#ip?add?1.1.1.2?255.255.255.0?
R1(config-if)#end?
R1#show?ip?int?bri
Interface??????????????????IP-Address??????OK??Method?Status????????????????Protocol
FastEthernet0/0????????????192.168.108.254?YES?manual?up????????????????????up??????
FastEthernet0/1????????????1.1.1.2?????????YES?manual?up????????????????????down????
FastEthernet0/2????????????unassigned??????YES?unset??up????????????????????down????
FastEthernet0/3????????????unassigned??????YES?unset??up????????????????????down????
FastEthernet0/4????????????unassigned??????YES?unset??up????????????????????down????
FastEthernet0/5????????????unassigned??????YES?unset??up????????????????????down????
FastEthernet0/6????????????unassigned??????YES?unset??up????????????????????down????
FastEthernet0/7????????????unassigned??????YES?unset??up????????????????????down????
FastEthernet0/8????????????unassigned??????YES?unset??up????????????????????down????
FastEthernet0/9????????????unassigned??????YES?unset??up????????????????????down????
FastEthernet0/10???????????unassigned??????YES?unset??up????????????????????down????
FastEthernet0/11???????????unassigned??????YES?unset??up????????????????????down????
FastEthernet0/12???????????unassigned??????YES?unset??up????????????????????down????
FastEthernet0/13???????????unassigned??????YES?unset??up????????????????????down????
FastEthernet0/14???????????unassigned??????YES?unset??up????????????????????down????
FastEthernet0/15???????????unassigned??????YES?unset??up????????????????????down????
Vlan1??????????????????????unassigned??????YES?unset??up????????????????????down????
R1#
[root@yunwei?cisco]#?

微信公眾號~運維少年

轉載于:https://blog.51cto.com/xiaowangzai/2405225

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