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Showing posts from November, 2021

Telnet and FTP in Wired networks using NS2 (Network Simulator 2)

Telnet and FTP for a Wired Networks This post tells about the use of Telnet and FTP in Network Simulator 2 for a wired network. This can be extended to a wireless network as well. The following is the source code for implementing Telnet and FTP application in a Wired network scenario.  The network looks like this: Telnet in NS2 Node 0 to Node 2 is enabled with Telnet Application and Node 1 to Node 3 is enabled with FTP Application.  Save the following file as wired.tcl #=================================== # Simulation parameters setup #=================================== set val(stop) 10.0 ;# time of simulation end #=================================== # Initialization #=================================== #Create a ns simulator set ns [new Simulator] #Open the NS trace file set tracefile [open out.tr w] $ns trace-all $tracefile #Open the NAM trace file set namfile [open out.nam w] $ns namtrace-all $namfile #=================================== # Nodes

Python SSL certificate verify error - Solved

Often we get an error in python in the ssl.c file namely: ssl.SSLCertVerificationError: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: The reason is your computer didnt have a valid certificate. There are many options in the internet and none of them worked. Here is the solution:  Download https://letsencrypt.org/certs/lets-encrypt-r3.pem  rename file .pem to .cer double click and install and then try to run app your SSL issue will resolved. Cheers !!! Here are the screenshots for the above operations SSL certificate Error SSL certificate Error SSL certificate Error SSL certificate Error SSL certificate Error SSL certificate Error