Linux – tftp 除錯

測試環境為 Ubuntu 16.04 x86_64.

tftp 常見的錯誤訊息

• PXE-E3B-TFTP Error file not found
  最近新設定一台 PXE 但使用 PXE 開機卻出現下面的錯誤訊息!

  PXE-T01: file not found
  PXE-E3B-TFTP Error file not found
  PXE-M0F exiting Intel boot agent
  

  使用 tcpdump 則是出現這樣的訊息

  IP tftp: 28 RRQ "/pxelinux.0" octet tsize 0
  

  也確定 tftp 服務是開啟的

  # netstat -an | fgrep -w 69
  udp        0      0 0.0.0.0:69              0.0.0.0:*
  

  查了半天才看出原來 /etc/xinetd.d/tftp 和 /etc/dhcpd.conf 目錄設定錯誤.

  #vi /etc/xinetd.d/tftp
  server_args = -s /tftpboot
  
  # vi /etc/dhcpd.conf
  filename “linux-install/pxelinux.0″
  

  dhcpd.conf 所指定的檔案目錄是以 tftp 為基準點,所以寫成 “filename “linux-install/pxelinux.0″;” 是指向 “/tftpboot/linux-install/pxelinux.0″;”

• PXE-E99: Unexptced network error
  這一次遇到的是 tftp IPv6 的問題.

  >> Start PXE over IPv6.
  Static IP address is 3FFE:501:666:100:0:0:0:2C
  Server IP address is 3FFE:501:666:100:0:0:0:1
  NBP filename is grubaa64.efi
  NBP filesize is 0 bytes
  PXE-E99: Unexptced network error
  

  tftp 設定要修改成 flags = IPv6 (會同時支援 Ipv4 與 IPv6)

  [root@benjr ~]# cat /etc/xinetd.d/tftp 
  # default: off
  # description: The tftp server serves files using the trivial file transfer \
  #                    protocol.  The tftp protocol is often used to boot diskless \
  #                    workstations, download configuration files to network-aware printers, \
  #                    and to start the installation process for some operating systems.
  service tftp
  {
                      disable          = no
                      socket_type      = dgram
                      protocol         = udp
                      wait             = yes
                      user             = root
                      server           = /usr/sbin/in.tftpd
                      server_args      = -s /var/lib/tftpboot
                      per_source       = 11
                      cps              = 100 2
                      flags            = IPv6
  }
  [root@benjr ~]# service xinetd restart
  

• PXE-E32: TFTP Open timeout
  另外一個常見的錯誤是

  PXE-E32: TFTP Open timeout
  

  可能的問題也跟前面一樣,需要在檢查一下你的 /etc/xinetd.d/tftp 和 /etc/dhcpd.conf 目錄設定.

• Unified Extensible Firmware Interface (UEFI)
  其他常見的錯誤訊息,可以先在本機使用 tftp 指令來除錯(如下所示).

  PXE-E07: Network device error.
  PXE-E16: No offer received.
  PXE-E18: Server response timeout.
  PXE-E99: Unexpected network error.
  

• error: disk not found
  這個是使用一般的 grubx64.efi 檔案,需改成給 PXE Boot 的 grubx64.efi 即可.

  >>Checking Media Presence......
  >>Media Present......
   Downloading NBP file...
  
    NBP file downloaded successfully.
  Fetching Netboot Image
  error: disk `tftp,192.10.10.1' not found.
  error: terminal `serial' isn't found.
  error: terminal `serial' isn't found.
  error: syntax error.
  error: Incorrect command.
  error: syntax error.
  

tftp 除錯

• tftp 指令
  如果檢查了半天還是不知哪裡出現問題,可在本機 Linux 使用 tftp 指令來檢視 tftp 的功能是否正常,除了 IPv4 外,也可以直接使用 IPv6 – #tftp 3ffe:501:6666:100::1 (你的 IPv6 IP).

  # tftp 172.16.0.2
  
  tftp> help
  tftp-hpa 0.49
  Commands may be abbreviated.  Commands are:
  
  connect         connect to remote tftp
  mode            set file transfer mode
  put             send file
  get             receive file
  quit            exit tftp
  verbose         toggle verbose mode
  trace           toggle packet tracing
  literal         toggle literal mode, ignore ':' in file name
  status          show current status
  binary          set mode to octet
  ascii           set mode to netascii
  rexmt           set per-packet transmission timeout
  timeout         set total retransmission timeout
  ?               print help information
  help            print help information
  

  試試看檔案可不可接收或傳送,如果可以應該就沒有問題了.

  tftp> get pxelinux.0
  getting from 172.16.0.2:pxelinux.0 to pxelinux.0 [netascii]
  Received 27213 bytes in 0.0 seconds [31745124 bit/s]
  tftp>quit
  #
  

root@ubuntu:~# vi /etc/default/tftpd-hpa
# /etc/default/tftpd-hpa
TFTP_USERNAME="tftp"
TFTP_DIRECTORY="/var/lib/tftpboot"
TFTP_ADDRESS=":69"
TFTP_OPTIONS="--secure -vvv"

root@ubuntu:~# vi /etc/xinetd.d/tftp
service tftp
{
  socket_type     = dgram
  protocol        = udp
  wait            = no
  user            = root
  server          = /usr/sbin/in.tftpd
  server_args     = -s /var/lib/tftpboot -vvv
  disable         = no
  per_source      = 11
  cps             = 100 2
  flags           = IPv4
}