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The use of ports allow computers/devices to run multiple services/applications. Just as the IP address identifies the computer, The network port identifies the application or service running on the computer. However an IP address alone is not sufficient for running network applications, as a computer can run multiple applications and/or services. The IP address identifies the device e.g. While (W5100.On a TCP/IP network every device must have an IP address. while (W5100.readSnSR(i) = SOCK_ESTABLISHED)
Telnet server multiple ports code#
Here’s the code for my TelnetServer class: #ifndef TELNETSERVER_Hīoolean connected(void) Since the console stops functioning at the point where things go wonky, I don’t yet know what’s going on. But I don’t know why it’s going wonky when the telnet session is disconnected. I have to believe this still has something to do with the other EthernetServer on port 80, as that is the only other code that is even aware the Ethernet exists. When I either open a second PuTTY instance, or close the first one, something is losing its mind, and the app crashes or at least stops communicating with the SerialMonitor. Put that change into my big app, and I can now open a single telnet session, which works fine. I added a line of code to make the telnet code ignore any sockets on port 80, and the test program works fine again. I figured maybe the fact that my application also runs an EthernetServer on port 80 for the web server could have something to do with the problem, so I added that to the test program, and sure enough it failed. I plumbed it into my big application, and as soon as I open a single telnet session, things go sideways. So close, yet so far… I took your code, turned it into a class which inherits from Stream, and built a test program, which works fine. So, how can I have more than one session on a given port, when the W5100 does not so much as give an indication that another client is even trying to connect? If I add a second EthernetServer listening on port 24, then I can open a PuTTY instance on port 23, open another PuTTY instance on port 24, and all works as expected (note my code currently explicitly closes the first connection when the second one opens). If I instead open a second PuTTY instance on any other port, the connection is established. The W5100 seems to be completely ignoring it. However, shortly after that, I opened another PuTTY instance, also on port 23, yet there is NO change of status on ANY socket resulting from that second PuTTY instance. Note that in the middle, a connection is established on port 23.
Telnet server multiple ports serial#
Whenever the status for any socket changes, it displays the change on the Serial Monitor. I have code that continuously polls the SnSR register on the W5100, and records the status for each of the four sockets. It all works just fine, except only a single session is allowed at any given time, on any given port. So, there is no communication/negotiation between the client and server - the port is opened, and data flows. I'm simply setting up an EthernetServer on port 23, and using the PuTTY telnet client in "passive" mode to communicate. But it still does not address the problem i seem to be seeing.įirst, I'm not really using a telnet server. I looked at your code when I first came up with this earlier this year.