telnet - user interface to the TELNET protocol
You can use this command for check the connection of a application.
telnet IPADDRESS PORT curl -v telnet://<host>:<port> telnet 192.168.0.10 80 <- http telnet 192.168.0.10 25 <- smtp
Check Connection and Close Connection.
# telnet localhost 25 Trying 127.0.0.1... Connected to localhost.localdomain (127.0.0.1). Escape character is '^]'. 220 office-sv1 ESMTP Sendmail 8.13.8/8.13.8; Mon, 28 Mar 2011 08:01:08 +0900 ^] <- Ctrl ] telnet> quit Connection closed.
GET / HTTP/1.0 <- http://HOST/index.html GET / HTTP/1.1 GET /test/sample.html HTTP/1.0 <- http://HOST/test/sample.html
# telnet localhost 80 Trying 127.0.0.1... Connected to localhost.joeswebhosting.net (127.0.0.1). Escape character is '^]'. GET / HTTP/1.0 <- Enter 2 times (http://localhost/index.html) HTTP/1.1 200 OK Date: Wed, 29 Jul 2009 15:16:50 GMT Server: Apache/1.3.37 (Unix) mod_fastcgi/2.4.6 mod_auth_passthrough/1.8 mod_log_bytes/1.2 mod_bwlimited/1.4 PHP/4.4.7 abbr. Last-Modified: Mon, 05 Feb 2007 11:04:57 GMT ETag: "1b200-b2c-45c70f59" Accept-Ranges: bytes Content-Length: 2860 Connection: close Content-Type: text/html <html> <html> <title>TEST</title> abbr. </body> </html> Connection closed by foreign host. #
# telnet localhost 25 Trying 127.0.0.1... Connected to test-server.test-server (127.0.0.1). Escape character is '^]'. 220 test-server.example-sec.local ESMTP helo localhost 250 test-server.example-sec.local mail from:user01@example-sec.jp 250 ok rcpt to:user02@example-sec.jp 250 ok 502 unimplemented (#5.5.1) data 354 go ahead From: user01@example-sec.jp To: user02@example-sec.jp Subject: test this is test. . 250 ok 1184072108 qp 20747 502 unimplemented (#5.5.1) quit 221 test-server.example-sec.local Connection closed by foreign host.