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I have a HP ProCurve switch, I recently added 2 new machines to the network, which I had to assign the IP addresses to manually. Now using these 2 machines I can ping my current machine and other machines on the network, however if I try to ping those 2 machines from my current machine (or others on the network) it does not go through. So my thoughts are that the router table has not updated so that's why I can't ping them from machines that have been on this router.
(Not too sure, not enough knowledge yet)
At least I think so. My question is does the Router Table update it's information automatically?
Assuming your HP Procurve is acting only as a switch, then the Routing Table should not be your problem. A switch does not route IPs, a switch is concerned with routing packets via their layer-2 addresses (MAC addresses). The switch determined which physical port is connected to a device with a MAC address, and when it gets a packet addressed to that MAC address, it sends the packet out that port. The mapping on port to destination mac address is stored in a CAM table inside the switch. This is very different from a routing table that maps IP address ranges to physical interfaces.
What is probably happening is that ARP is not resolving. ARP binds layer 3 IPs to layer 2 MACs in a local network. This can be cause for a few reasons. The first thing i would look into is if the switch has VLANs enabled. This makes the switch act like multiple isolated switches. After that you may need to look at your computers ARP tables to make sure they are correct. The arping command will be useful.
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I have read somewhere that "if you are the remote user connecting to a web server, then your web browser would pick a random TCP port from a certain range of port numbers, and attempt to connect to port 80 on the IP address of the web server". Does that mean that a particular ip address at client side have multiple ports?
Every system which implements TCP/IP has multiple "ports". The IP address refers to the entire system, if that's all we had it would be pretty boring. One program on a system could talk to one program on another system.
Hence the idea of "ports". Ports are just a 16-bit number which "completes" the address. So, your program on system 1.2.3.4 wants to talk to the webserver running on 2.3.4.5. The webserver "binds" itself to port 80. This is an example of a "well known port". But, how is the webserver to get data back to you? Your program needs a "port" of its own. But, it can be any old number, it doesn't need to be well known, so it just tells the OS I need a port and the OS finds one not in use and your program is "bound" to that port. Say it is port 3456.
So now we have all we need: 1.2.3.4:3456 can talk to 2.3.4.5:80
and when the packets of data for port 80 arrive at 2.3.4.5, the OS delivers them to the webserver. And when the packets of data for port 3456 arrive back at your computer (1.2.3.4), your OS delivers them to your web browser.
Whereever you read that, it's wrong. The TCP implementation picks a random local port. Not the browser. There are 65535 TCP ports per IP address, and another 65535 UDP ports.
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We have a computer that needs to communicate with two routers over one physical ethernet interface. I know this sounds weird, but each router is actually interfaced to an Iridium L Band receiver/transmitter, and we are hoping to double our bandwidth by using two.
I would like to be able to select which link to send data over at the application level, but I'm not quite sure how to do it. My first thought was to establish a virtual IP address in addition to the pre-configured static IP address and use two separate sockets to send() data out over each "interface" separately. My question is, how do I make it so that only one of the routers actually routes the data out to a remote host? The IP addresses and subnet masks of the Iridium transceivers are configurable. Is it possible to make one transceiver only listen to the data coming from one computer IP address? Subnets maybe?
Create vlan inter faces in your machine
ip link add link eth0 name eth0.1 type vlan id 10
ip link add link eth0 name eth0.2 type vlan id 20
assign ip address to eth0.1 and eth0.2 in two networks. Later you can choose which one to bind at application level.
say like this
ifconfig eth0.1 192.168.10.2/24 up
ifconfig eth0.2 192.168.20.2/24 up
Then configure your router in two networks rather than one. Your computer and the routers should be connected to trunk port in the switch. Configure your routers to be in two networks rather than same. Configure subinterfaces in routers so that they listen for vlan 10 and 20 respectively. (how exactly to do this depends on the type of router) I can give you commands only for cisco.
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Here is the scenery. I have several buildings with same subnet IP addresses (192.168.0.0/24).
I need to secure that connection with OpenVPN.
Please assist me how can I organize VPN connection with IP network 10.10.10.0/24
example
HQ (192.168.0.0/24) - VPN 1 (10.10.10.50) --- VPN 2 (10.10.10.51) - Branch (192.168.0.0/24)
I meas assist with NAT if it will be needed or if I just connect , the C class traffic will just be passed through.
Thank you
Since you are merging two nets, you should use TAP interfaces.
TAP (as in network tap) simulates a link layer device and it operates with layer 2 packets such as Ethernet frames. TUN (as in network TUNnel) simulates a network layer device and it operates with layer 3 packets such as IP packets. TAP is used to create a network bridge, while TUN is used with routing.
This way, you will be joining the HQ network with the branch network like if you plug a (secure, pre-shared key may be ok) ethernet cable between them.
But this will likely crash both environments if they are operating now without knowing one about each other. Maybe the HQ router has the same IP as the branch one, or maybe not, but they are both acting as DHCP servers and now they will be on the same network.
Do you really need to merge both nets? I think you should consider to do some network design and let the HQ on the 192.168.0.0/24 but change the n-th branch to 192.168.n.0/24. Then you can do a TUN OpenVPN setup and route between branches and HQ in a hierachical way. It will save you some bandwith too by not spreading irrelevant broadcast traffic over the tunnel.
Thank you
Well you know, I do not have any router installed in HQ side or anywhere in network and maybe that is a big minus (and I will fix that in a time). Now I just need to secure the links between HQ and branches so the optical network provider (that provides links) could not access out data. If you have any good solution please write.
Thank you
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I understand that a router uses NAT to translate the public IP we get from the ISP to say 300 local IPs. Does a switch perform the same function? If not, how's it different?
No, a switch cannot perform NAT and translate public(s) IP addresses into private addresses.
A switch is a network device that filters and forwards packets between LAN segments. Switches operate at the data link layer (layer 2). So, they are not aware of IP addresses which are network layer (layer 3). A switch keeps a record of the MAC addresses of all the devices connected to it. With this information, a switch can identify which system is sitting on which port. So when a frame is received, it knows exactly which port to send it to, without significantly increasing network response times.
Routers are network devices used to interconnect two different networks (with different IP addressing schemes).
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whats the purpose of local IP addresses if there are mac addresses? ARP maps mac addresses to IP addresses but I don't see why it's needed, because I thought data on LANs are sent as frames which only care about the mac addresses.
Long ago and far away, there was more to the world than Ethernet LANs, and application writers didn't care whether your PC was attached to an Ethernet, a Token Ring, an XNS net, or dial-up. IP provides a layer of abstraction and coherence across the top of all those and many more, allowing application authors to ignore the differences between them.
And what happens if you want to talk to a macine that isn't on your local area network (such as StackOverflow).
IP allows routing of packets anywhere, not just locally in your current network segment and, though it's mostly over Ethernet now, IP can equally well work over other underlying layers, giving a consistent view to the upper layers. This is vital given how much stuff is actually built on IP (DNS, FTP, SSH, HTTP and so on).
Machines almost certainly will cache IP-to-ethernet details to speed up subsequent transfers so the impact of translation on the LAN isn't so bad.