Network service troubleshooting and port scanning

At a former workplace, the DB2 team were furious because they couldn’t connect to the database remotely. They have been constantly trying to telnet into a port on the server and they couldn’t. They server wasn’t listening on the port they were trying to telnet into. They have rebooted the server twice and nobody thought of checking the listening ports. The solution was a simple restart of the DB service.

Ping the server. If the server does not respond to ping, access the server locally by way of RDP, IMM , RSA ,CIMC or UCS Manager KVM Console and troubleshoot from there. If the server does reply to ping, scan the port. Continue reading

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df does not show all NFS mounts in RHEL 7.1

This is due to a bug in coreutils. It is fixed in coreutils-8.22-12.el7_1.2. df is a part of coreutils package.

# rpm -qf `which df`
coreutils-8.22-11.el7.x86_64

As a workaround, use

    #  df -t nfs -a

    #  grep nfs /etc/mtab

    #  cat /proc/mounts | grep nfs