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12

ARP Connection oriented or connectionless? Connectionless - it's just a request and a response (or a broadcast just letting everyone know about something). It uses TCP It doesn't use TCP - TCP is a layer 4 protocol, whereas ARP is glue between layers 2 and 3.


3

If you're looking for the short answer, it (the router/firewall) already knows all it needs to for the TCP "response" from the session table and routing table. A generic example would look like: If it needs to, the router can run an ARP request same as it would anytime it needs to do a MAC address lookup. But it would typically be for local devices, ...


3

Use the command: ss -neopt state established This will show you only TCP sessions in ESTABLISHED state, no piping to other commands required, so it's super fast. ss is better than netstat because the older netstat just reads from procfs which is subject to file locks. ss actually makes a query inside the kernel which is handled by the kernel scheduler ...


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Since the answer body has to be at least 30 symbols, I need to write some stuff here, even the totally dull one, though netstat -aun or even man netstat would be enough.


2

No for built-in tool. Only way I can think of is to use the winpcap/npf library to build your own tool to make up stat that you need. In windows the network stack is stripped compared to the Linux/BSD's side. Thus the need for winpcap&npf driver. I would add that even the windows firewall is a pseudo-stateless firewall (layer 4 and it just check tcp ...


2

There are two methods that can be used to handle ARP traffic when NAT is not used. The traffic can be bridged, and the VM will receive and respond to the ARP request on it own. The traffic can be routed, and the VM's host responds with a ProxyARP response. It is also common to us NAT for a VM. In this case the source address (and possibly port) are ...


1

Yes, there is. Using a tap device causes context switches between the client process and the process that holds the tap device. It also causes additional copies, as data needs to be copied from the client process into the kernel, and then from the kernel into the tap holder. However, Linux is pretty good at context switching, and in-cache copies are ...


1

I'm posting this as an answer due to insufficient commenting permissions. From my experience VPN over tcp - tap was abysmal at best over wireless connections due to the the nature of TCP. When switching to UDP no more connection timeouts occurred - even better with tun device. I would suggest you test under poor network connections both TCP and UDP and ...


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The easiest solution is to use balance source, but if many clients come from the same IP, it may not be very fair on your backend servers. See http://blog.haproxy.com/2013/04/22/client-ip-persistence-or-source-ip-hash-load-balancing/ for more discussion on methods to accomplish this.


1

So, my question is - how do I put http://www.baidu.com instead of / (SLASH) in GET request? The request you want to have is not a bad one, but just a proxy request. To create it just specify your target host as a proxy. Apart from that curl might be not the right tool to generate real bad requests.


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Netstat -s is a more intuitive display of /proc/net/netstat. Counters in it are global and not per interface. To get that kind of information you will need to use/write a monitoring tool using libpcap.


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netsh interfaces ipv4 show {tcp,ip,udp}stats gives you some additional information over netstat, but it might not be enough. MS Technet article on netsh ipv4



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