Redhat network registration problem

Linux and Unix-Like Red Hat
1

Dear members & admins

I have 3 RHEL 5.7 servers. So I decided to upgrade them to latest version. 2 of them successfully upgraded to RHEL 5.11 and last one is the problem.

When I hit rhn_register command server shows following info :

#rhn_register
There was an SSL error: (104, 'Connection reset by peer')
A common cause of this error is the system time being incorrect. Verify that the time on this system is correct.

Below are steps I have tried.

  1. So I checked data and timezone on the server. They all correct.
    Checked /var/log/up2date log file. Following errors occured.
rhn_register A protocol error occured: Service Unavailable , attempt #1,
rhn_register A protocol error occured: Service Unavailable , attempt #2,

  1. Checked the https and http connection to xmlrpc.rhn.redhat.com with telnet tool. Successfully connected via https and http.

  2. Replaced http instead of https in /etc/sysconfig/rhn/up2date file and tried to register with rhn. But with no luck.

  3. Checked root certificates. They all fine.

Now I'm running out of ideas. Is there anything to check?
Thanks guys

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Moderator comments were removed during original forum migration.
3

Ma bad, it was network issue. Our network admin wrote wrong rule on the firewall.