Have to recomment the Exploring Expect book for all expect programmers — invaluable. I’ve rewritten your code: (untested) proc login {user pass} { expect “login:” send “$user\r” expect “password:” send “$pass\r” } set username spongebob set passwords {squarepants rhombuspants} set index 0 spawn telnet 192.168.40.100 login $username [lindex $passwords $index] expect { “login incorrect” { … Read more
Interesting. I had more luck sending IAC WILL ECHO IAC WILL SUPPRESS_GO_AHEAD IAC WONT LINEMODE 255 251 1 255 251 3 255 252 34 The IAC WONT LINEMODE seems to be redundant: my telnet client seems to get to the right state without it, but I left it in for completeness.
While I’d suggest using expect, too, for non-interactive use the normal shell commands might suffice. telnet accepts its command on stdin, so you just need to pipe or write the commands into it through heredoc: telnet 10.1.1.1 <<EOF remotecommand 1 remotecommand 2 EOF (Edit: Judging from the comments, the remote command needs some time to … Read more
The ‘\r’ character is the carriage return, and the carriage return-newline pair is both needed for newline in a network virtual terminal session. From the old telnet specification (RFC 854) (page 11): The sequence “CR LF”, as defined, will cause the NVT to be positioned at the left margin of the next print line (as … Read more
As pointed by B. Rhodes, nc (netcat) will do the job. A more compact way to use it: nc -z <host> <port> That way nc will only check if the port is open, exiting with 0 on success, 1 on failure. For a quick interactive check (with a 5 seconds timeout): nc -z -v -w5 … Read more
Best C# Telnet Lib I’ve found is called Minimalistic Telnet. Very easy to understand, use and modify. It works great for the Cisco routers I need to configure. http://www.codeproject.com/KB/IP/MinimalisticTelnet.aspx
There are two methods you can sometimes use to determine if a recipient actually exists: You can connect to the server, and issue a VRFY command. Very few servers support this command, but it is intended for exactly this. If the server responds with a 2.0.0 DSN, the user exists. VRFY user You can issue … Read more