CentOS5 Telnet Server problem

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altrom
Posts: 1
Joined: 2007/04/30 15:36:31
Location: Vancouver, BC
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CentOS5 Telnet Server problem

Post by altrom » 2007/04/30 19:05:34

Hello All,

I have a number of servers in different locations, and we were in the process of upgrading our really old SCO boxes to CentOS 4.4, which went very well. Due to the need for the users on the various servers to access other servers, we needed to use Telnet (as the old SCO boxes don't have SSH). I installed Telnet-server, changing the xinitd file and everything works fine.

I decided to try installing CentOS5 for the next server upgrade and everything appeared to be fine. Installed the telnet-server, changed xinit to enable it, tested telnet from my server, everything is fine.

I then sent it out, and a number of people can't access the new server via telnet, though many can. I have even seen where 2 people sitting side by side, with the same version of windows, one gets in, one doesn't.

The new CentOS 5 server is br15(192.168.15.100). From the server I work from, br01(192.168.1.100), I can access the new using telnet. From another server BR04(192.168.4.100), I get an error. I have tried with multiple servers and desktops and some connect, some don't. With some if the desktops that can't use Windows command line or Putty to telnet, I can use Putty and SSH and get in no problem. Everyone can see the server, everyone pings it fine.

The CentOS 5 server firewall has been disabled, SELINUX has been been disabled. Our DNS server is running on CentOS 4.4 on a seperate server. It doesn't seem to matter if the connecting computers are on the same or different sub-nets.

If anyone has any suggestions, I'd love to hear them, as this is driving me batty.

2 SCO servers set up exactly the same. Here is an example, br01 works fine, br04 and a windows telnet session crap out.

=================

#br01) uname -a
SCO_SV br01 3.2 2 i386

#br01) cat resolv.conf
;
; /etc/resolv.conf
;
; Primary Name Server is ho ( 192.168.1.101 )
;
domain altrom.com
nameserver 192.168.1.106
nameserver 192.168.1.101
hostresorder local bind

#br01) cat /etc/hosts | grep br15
192.168.15.10 br15laser1 br15laser1.altrom.com
192.168.15.100 br15 br15.altrom.com

#br01) cat /etc/hosts | grep 15.100
192.168.15.100 br15 br15.altrom.com

------


#br04) uname -a
SCO_SV br01 3.2 2 i386

#br04)cat /etc/resolv.conf
;
; /etc/resolv.conf
;
; Primary Name Server is ho ( 192.168.1.101 )
;
domain altrom.com
nammeserver 192,168.1.106
nameserver 192.168.1.101
hostresorder local bind

#br04) cat /etc/hosts | grep br15
192.168.15.10 br15laser1 br15laser1.altrom.com
192.168.15.100 br15 br15.altrom.com

#br04) cat /etc/hosts | grep 15.100
192.168.15.100 br15 br15.altrom.com


=================


#br01) telnet br15
Trying 192.168.15.100...
Connected to br15.
Escape character is '^]'.
CentOS release 5 (Final)
Kernel 2.6.18-8.1.1.el5xen on an x86_64
login: sysmgr
Password:
Last login: Mon Apr 30 12:17:56 from br15

------

#br04) telnet 192.168.15.100
Trying 192.168.15.100...
Connected to 192.168.15.100.
Escape character is '^]'.
getnameinfo: localhost: Success
Connection closed by foreign host.

------

From WINDOWS
C:\>ping br15

Pinging br15 [192.168.15.100] with 32 bytes of data:

Reply from 192.168.15.100: bytes=32 time=103ms TTL=64
Reply from 192.168.15.100: bytes=32 time=110ms TTL=64
Reply from 192.168.15.100: bytes=32 time=109ms TTL=64
Reply from 192.168.15.100: bytes=32 time=108ms TTL=64

Ping statistics for 192.168.15.100:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 103ms, Maximum = 110ms, Average = 107ms

c:\> telnet 192.168.15.100
getnameinfo: localhost: Success
Temporary failure in name resolution: Illegal see
k


Connection to host lost.
=========================================

michaelnel
Posts: 1478
Joined: 2006/05/29 16:50:11
Location: San Francisco, CA

CentOS5 Telnet Server problem

Post by michaelnel » 2007/04/30 21:22:59

[quote]
; /etc/resolv.conf
;
; Primary Name Server is ho ( 192.168.1.101 )
;
domain altrom.com
nameserver 192.168.1.106
nameserver 192.168.1.101
[/quote]

I think the line below is supposed to be in /etc/hosts.conf, not /etc/resolv.conf

hostresorder local bind

... and at least in linux, it's "order hosts,bind"

[quote]#br01) cat /etc/hosts | grep br15
192.168.15.10 br15laser1 br15laser1.altrom.com
192.168.15.100 br15 br15.altrom.com

#br01) cat /etc/hosts | grep 15.100
192.168.15.100 br15 br15.altrom.com[/quote]

Not sure if it matters, but in /etc/hosts I think the order is:

ipaddress fqdn aliases

You seem to have fqdn and aliases reversed. Again, not sure if it matters, and maybe SCO is different.

Do you have a localhost line in /etc/hosts?

Personally, I think it'd be wiser to get ssh running on the SCO boxes than to get telnetd with all its security problems working on the CentOS box.

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