疑難排解TACACS驗證問題

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已更新: 2023 年 8 月 3 日
文件 ID:200467

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    簡介

    本檔案介紹疑難排解Cisco IOS®/Cisco IOS-XE路由器和交換器上的TACACS驗證問題的步驟。

    必要條件

    需求

    思科建議您瞭解以下主題的基本知識：

    • 思科裝置上的驗證、授權及記帳(AAA)組態
    • TACACS配置

    採用元件

    本文件所述內容不限於特定軟體和硬體版本。

    本文中的資訊是根據特定實驗室環境內的裝置所建立。文中使用到的所有裝置皆從已清除（預設）的組態來啟動。如果您的網路運作中，請確保您瞭解任何指令可能造成的影響。

    TACACS的運作方式

    TACACS+通訊協定使用傳輸控制通訊協定(TCP)作為傳輸通訊協定，且目的地連線埠號碼為49。當路由器收到登入請求時，它會與TACACS伺服器建立TCP連線，並在連線後向使用者顯示使用者名稱提示。使用者輸入使用者名稱時，路由器會再次與TACACS伺服器通訊以取得密碼提示。使用者輸入密碼後，路由器會再次將此資訊傳送到TACACS伺服器。TACACS伺服器驗證使用者憑證並將響應傳送迴路由器。AAA作業階段的結果可以是以下任一結果：

    PASS：只有路由器上配置了AAA授權後，服務才開始進行身份驗證。此時開始授權階段。

    FAIL：身份驗證失敗後，可能會拒絕您進一步訪問，或提示您按順序重試該日誌。取決於TACACS+後台程式。在此示例中，如果從伺服器收到FAIL，則可以檢查為TACACS伺服器中的使用者配置的策略

    錯誤：它表示身份驗證過程中出現錯誤。這可以是在守護程式上，也可以是在守護程式和路由器之間的網路連線中。如果收到ERROR響應，路由器通常會嘗試使用其他方法驗證使用者。

    以下是思科路由器上AAA和TACACS的基本配置

    aaa new-model

aaa authentication log in default group tacacs+ local

aaa authorization exec default group tacacs+ local

!

tacacs server prod

address ipv4 10.106.60.182

key cisco123

!

ip tacacs source-interface Gig 0/0

    排除TACACS故障

    步驟 1.

    在連線埠49上使用具有適當來源介面的路由器通過telnet驗證與TACACS伺服器的連線。如果路由器無法連線到連線埠49上的TACACS伺服器，可能會有一些防火牆或存取清單封鎖流量。

    Router#telnet 10.106.60.182 49
Trying 10.106.60.182, 49 ... Open

    步驟 2.

    驗證TACACS伺服器上是否正確配置了AAA客戶端及正確的IP地址和共用金鑰。如果路由器有多個傳出介面，建議使用此命令配置TACACS源介面。您可以將介面（其IP地址配置為TACACS伺服器上的客戶端IP地址）配置為路由器上的TACACS源介面

    Router(config)#ip tacacs source-interface Gig 0/0

    步驟 3.

    驗證TACACS來源介面是否位於虛擬路由和轉送(VRF)上。如果介面位於VRF上，您可以在AAA伺服器組下配置VRF資訊。有關VRF感知TACACS的配置，請參閱TACACS配置指南。

    步驟 4.

    執行測試aaa並驗證我們是否從伺服器收到正確的響應

    Router#test aaa  group tacacs+ cisco cisco legacy
Sending password
User successfully authenticated

    步驟 5.

    如果測試aaa失敗，請同時啟用這些調試，以分析路由器和TACACS伺服器之間的事務以確定根本原因。

    debug aaa authentication

debug aaa authorization

debug tacacs

debug ip tcp transaction

    以下是工作情境中的偵錯輸出範例：

    *Apr  6 13:32:50.462: AAA/BIND(00000054): Bind i/f  
*Apr  6 13:32:50.462: AAA/AUTHEN/LOGIN (00000054): Pick method list 'default'
*Apr  6 13:32:50.462: TPLUS: Queuing AAA Authentication request 84 for processing
*Apr  6 13:32:50.462: TPLUS(00000054) log in timer started 1020 sec timeout
*Apr  6 13:32:50.462: TPLUS: processing authentication start request id 84
*Apr  6 13:32:50.462: TPLUS: Authentication start packet created for 84()
*Apr  6 13:32:50.462: TPLUS: Using server 10.106.60.182
*Apr  6 13:32:50.462: TPLUS(00000054)/0/NB_WAIT/2432818: Started 5 sec timeout
*Apr  6 13:32:50.466: TPLUS(00000054)/0/NB_WAIT: socket event 2
*Apr  6 13:32:50.466: TPLUS(00000054)/0/NB_WAIT: wrote entire 38 bytes request
*Apr  6 13:32:50.466: TPLUS(00000054)/0/READ: socket event 1
*Apr  6 13:32:50.466: TPLUS(00000054)/0/READ: Would block while reading
*Apr  6 13:32:50.466: TPLUS(00000054)/0/READ: socket event 1
*Apr  6 13:32:50.466: TPLUS(00000054)/0/READ: read entire 12 header bytes (expect 43 bytes data)
*Apr  6 13:32:50.466: TPLUS(00000054)/0/READ: socket event 1
*Apr  6 13:32:50.466: TPLUS(00000054)/0/READ: read entire 55 bytes response
*Apr  6 13:32:50.466: TPLUS(00000054)/0/2432818: Processing the reply packet
*Apr  6 13:32:50.466: TPLUS: Received authen response status GET_USER (7)
*Apr  6 13:32:53.242: TPLUS: Queuing AAA Authentication request 84 for processing
*Apr  6 13:32:53.242: TPLUS(00000054) log in timer started 1020 sec timeout
*Apr  6 13:32:53.242: TPLUS: processing authentication continue request id 84
*Apr  6 13:32:53.242: TPLUS: Authentication continue packet generated for 84
*Apr  6 13:32:53.242: TPLUS(00000054)/0/WRITE/10882BBC: Started 5 sec timeout
*Apr  6 13:32:53.242: TPLUS(00000054)/0/WRITE: wrote entire 22 bytes request
*Apr  6 13:32:53.246: TPLUS(00000054)/0/READ: socket event 1
*Apr  6 13:32:53.246: TPLUS(00000054)/0/READ: read entire 12 header bytes (expect 16 bytes data)
*Apr  6 13:32:53.246: TPLUS(00000054)/0/READ: socket event 1
*Apr  6 13:32:53.246: TPLUS(00000054)/0/READ: read entire 28 bytes response
*Apr  6 13:32:53.246: TPLUS(00000054)/0/10882BBC: Processing the reply packet
*Apr  6 13:32:53.246: TPLUS: Received authen response status GET_PASSWORD (8)
*Apr  6 13:32:54.454: TPLUS: Queuing AAA Authentication request 84 for processing
*Apr  6 13:32:54.454: TPLUS(00000054) log in timer started 1020 sec timeout
*Apr  6 13:32:54.454: TPLUS: processing authentication continue request id 84
*Apr  6 13:32:54.454: TPLUS: Authentication continue packet generated for 84
*Apr  6 13:32:54.454: TPLUS(00000054)/0/WRITE/2432818: Started 5 sec timeout
*Apr  6 13:32:54.454: TPLUS(00000054)/0/WRITE: wrote entire 22 bytes request
*Apr  6 13:32:54.458: TPLUS(00000054)/0/READ: socket event 1
*Apr  6 13:32:54.458: TPLUS(00000054)/0/READ: read entire 12 header bytes (expect 6 bytes data)
*Apr  6 13:32:54.458: TPLUS(00000054)/0/READ: socket event 1
*Apr  6 13:32:54.458: TPLUS(00000054)/0/READ: read entire 18 bytes response
*Apr  6 13:32:54.458: TPLUS(00000054)/0/2432818: Processing the reply packet
*Apr  6 13:32:54.458: TPLUS: Received authen response status PASS (2)
*Apr  6 13:32:54.462: AAA/AUTHOR (0x54): Pick method list 'default'
*Apr  6 13:32:54.462: TPLUS: Queuing AAA Authorization request 84 for processing
*Apr  6 13:32:54.462: TPLUS(00000054) log in timer started 1020 sec timeout
*Apr  6 13:32:54.462: TPLUS: processing authorization request id 84
*Apr  6 13:32:54.462: TPLUS: Protocol set to None .....Skipping
*Apr  6 13:32:54.462: TPLUS: Sending AV service=shell
*Apr  6 13:32:54.462: TPLUS: Sending AV cmd*
*Apr  6 13:32:54.462: TPLUS: Authorization request created for 84(cisco)
*Apr  6 13:32:54.462: TPLUS: using previously set server 10.106.60.182 from group tacacs+
*Apr  6 13:32:54.462: TPLUS(00000054)/0/NB_WAIT/2432818: Started 5 sec timeout
*Apr  6 13:32:54.462: TPLUS(00000054)/0/NB_WAIT: socket event 2
*Apr  6 13:32:54.462: TPLUS(00000054)/0/NB_WAIT: wrote entire 62 bytes request
*Apr  6 13:32:54.462: TPLUS(00000054)/0/READ: socket event 1
*Apr  6 13:32:54.462: TPLUS(00000054)/0/READ: Would block while reading
*Apr  6 13:32:54.470: TPLUS(00000054)/0/READ: socket event 1
*Apr  6 13:32:54.470: TPLUS(00000054)/0/READ: read entire 12 header bytes (expect 18 bytes data)
*Apr  6 13:32:54.470: TPLUS(00000054)/0/READ: socket event 1
*Apr  6 13:32:54.470: TPLUS(00000054)/0/READ: read entire 30 bytes response
*Apr  6 13:32:54.470: TPLUS(00000054)/0/2432818: Processing the reply packet
*Apr  6 13:32:54.470: TPLUS: Processed AV priv-lvl=15
*Apr  6 13:32:54.470: TPLUS: received authorization response for 84: PASS
*Apr  6 13:32:54.470: AAA/AUTHOR/EXEC(00000054): processing AV cmd=
*Apr  6 13:32:54.470: AAA/AUTHOR/EXEC(00000054): processing AV priv-lvl=15
*Apr  6 13:32:54.470: AAA/AUTHOR/EXEC(00000054): Authorization successful

    當TACACS伺服器配置了錯誤的預共用金鑰時，這是來自路由器的調試輸出示例。

    *Apr  6 13:35:07.826: AAA/BIND(00000055): Bind i/f  
*Apr  6 13:35:07.826: AAA/AUTHEN/LOGIN (00000055): Pick method list 'default'
*Apr  6 13:35:07.826: TPLUS: Queuing AAA Authentication request 85 for processing
*Apr  6 13:35:07.826: TPLUS(00000055) log in timer started 1020 sec timeout
*Apr  6 13:35:07.826: TPLUS: processing authentication start request id 85
*Apr  6 13:35:07.826: TPLUS: Authentication start packet created for 85()
*Apr  6 13:35:07.826: TPLUS: Using server 10.106.60.182
*Apr  6 13:35:07.826: TPLUS(00000055)/0/NB_WAIT/225FE2DC: Started 5 sec timeout
*Apr  6 13:35:07.830: TPLUS(00000055)/0/NB_WAIT: socket event 2
*Apr  6 13:35:07.830: TPLUS(00000055)/0/NB_WAIT: wrote entire 38 bytes request
*Apr  6 13:35:07.830: TPLUS(00000055)/0/READ: socket event 1
*Apr  6 13:35:07.830: TPLUS(00000055)/0/READ: Would block while reading
*Apr  6 13:35:07.886: TPLUS(00000055)/0/READ: socket event 1
*Apr  6 13:35:07.886: TPLUS(00000055)/0/READ: read entire 12 header bytes (expect 6 bytes data)
*Apr  6 13:35:07.886: TPLUS(00000055)/0/READ: socket event 1
*Apr  6 13:35:07.886: TPLUS(00000055)/0/READ: read entire 18 bytes response
*Apr  6 13:35:07.886: TPLUS(00000055)/0/225FE2DC: Processing the reply packet
*Apr  6 13:35:07.886: TPLUS: received bad AUTHEN packet: length = 6, expected 43974
*Apr  6 13:35:07.886: TPLUS: Invalid AUTHEN packet (check keys).

    相關資訊

    修訂記錄

    修訂 發佈日期 意見
    3.0
    03-Aug-2023
    已更新目錄、簡介、樣式要求、機器翻譯和格式。
    2.0
    14-Jul-2022
    針對格式、樣式要求、機器翻譯、連結更新等進行了更新。
    1.0
    30-Apr-2016
    初始版本
    TAC Authored

    由思科工程師貢獻

    • Rachika Koothan
      Cisco TAC Engineer

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