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Nov
18
2009

  • Cannot determine ethernet address for proxy ARP 

     

     This is due to an issue with the pppd program, which attempts to find a hardware interface on the subnet to which the pppd client has been assigned. In this case its looking for a hardware interface on the 192.168.5.0 subnet. It will fail to find one, and will drop the proxyarp request. 

     

     The simplest way around this problem, and the one that is suggested in the pppd documentation, is to set the pppd client IP assignment to be on the local subnet. An example in this case might be 192.168.56.129. However, it may not be possible to do that. In the case of a fully loaded subnet, there may not be any addresses to spare. Or there may be some security issues with giving out local subnet addresses. What to do? 

     

     The place to look is in the arp table. If you run tcpdump on host (192.168.56.12) during the time when client is pinging, you will see unanswered arp requests from host attempting to find the hardware address for 192.168.5.12. You need to proxy the hardware address of the pptp_srvr for client in order for this request to be fulfilled. This is the job of proxyarp. However, proxyarp has let us down in this instance, and we need to find a workaround. 

     

     This can be done manually using the arp command on pptp_srvr. For example, if the ethernet card on pptp_srvr is eth0, you could force the arp to proxy the client pptp address by saying 

    	arp --use-device --set 192.168.5.12 eth0 pub 

     You should now be able to ping from client to host through the pptp connection. 

Oct
27
2005

  • If you want to give that old computer new life on your home network, try using it as a file server for music or pictures or whatever so that no matter where in the house you are you can access your massive digital library from any computer. Here’s what you’ll need to do…     
Oct
23
2005

  • 由我国域名注册管理机构中国互联网络信息中心（CNNIC）举办的此次CN域名大赛，引起了各界广泛关注。此次域名评选活动的成功举办，不仅让众多优秀CN域名的价值得到了彰显，促进更多企事业单位重视对CN域名的保护，同时有助于引导理性的、有价值的CN域名投资，将为进一步增强我国顶级域名的国际竞争力和总体实力起到推动作用。
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