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Operating Systems Linux Red Hat Kernel thinks tcp port in use but isnt Post 302590852 by skkool22 on Tuesday 17th of January 2012 08:24:52 PM
Old 01-17-2012
Kernel thinks tcp port in use but isnt

I have a RHEL 5.5 system that i see this behavior on:

# uname -a
Linux myhost 2.6.18-194.17.4.0.1.el5 #1 SMP Tue Oct 26 20:10:33 EDT 2010 x86_64 x86_64 x86_64 GNU/Linux

#using netcat to listen to a port tells me its in use.
$ nc -l myhostip 33371
nc: Address already in use
$

# trying to telnet to the port
$ telnet myhostip 33371
Trying myhostip...
telnet: connect to address myhostip: Connection refused
telnet: Unable to connect to remote host: Connection refused

# lsof doesn't agree. returns nothing
$ lsof | grep 33371
$

# another option to lsof thats supposed to find sockets. returns nothing.
$ lsof -i :33371
$

# netstat -an doesn't show the port listening or in time_wait or in close_wait state.
$ netstat -an | grep 33371
$

Anyone have any idea on how to figure out what is using that port? I don't want to just reboot to fix.
 

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telnetrc(4)						     Kernel Interfaces Manual						       telnetrc(4)

NAME
telnetrc, .telnetrc - Specifies setup commands for a telnet session SYNOPSIS
$HOME/.telnetrc DESCRIPTION
The .telnetrc file contains the setup information for a telnet session. It is a hidden file in your home directory and must be readable by the user logging in. The file can consist of multiple entries for each remote host to which a user can connect. A remote host entry consists of multiple lines. The first line is the name of a remote host. The subsequent lines must begin with blank spaces, and contain telnet subcommands. These sub- commands are processed as though they were typed in manually. Lines beginning with a number sign (#) are comment lines. See telnet(1) for a complete list of telnet subcommands. To specify subcommands that apply to all systems, create an entry, using the word "DEFAULT" as the system name, and specify the telnet sub- commands in the subsequent lines. EXAMPLES
The following shows a sample .telnetrc file: # Beginning of telnetrc file # Default subcommands that apply to all systems DEFAULT environ undefine USER # First system entry system1 set echo toggle crlf # Second system entry system2 set echo mode line toggle crlf FILES
User-customized telnet startup values. RELATED INFORMATION
Commands: telnet(1). delim off telnetrc(4)
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