I was recently installing Oracle 19c RAC on a pair of servers running OEL8 UEK.

During the install of Grid Infrastructure the installer repeatedly failed the verification check stating that:

“[INS-06006] Passwordless SSH connectivity not set up between the following nodes(s)”

It is worth remembering that Oracle offers a relatively simple method to set up passwordless ssh connections between machines, which I had used prior to trying to install RAC:

In the Grid Infrastructure directory there is a script called sshUserSetup.sh

And you can use it as follows:

./sshUserSetup.sh -user oracle -hosts "dsib0251 dsib0252" -noPromptPassphrase -confirm -advanced

I had also used the runcluvfy.sh script to check that Oracle thought that the system was ready for a RAC install:

[oracle@dsib0251 grid]$ ./runcluvfy.sh comp nodecon -n dsib0251,dsib0252 -verbose

Verification of node connectivity was successful.

CVU operation performed: node connectivity
Date: Jun 7, 2022 3:17:26 PM
CVU home: /u01/app/19c/grid
User: oracle

MOS Note 2555697.1 ended up being the most helpful in solving this problem.

But since the problem impacted both installed Grid Infrastructure, and the database software, I ended up using two approaches.

The problem apparently is caused by OpenSSH being upgraded to 8.x which I assume is the default with OEL8. You can verify your system as follows:

[oracle@dsib0251]$ ssh -V
OpenSSH_8.0p1, OpenSSL 1.1.1k FIPS 25 Mar 2021

To solve the GI installer issue I decided to apply patch 30159782. Of course, Oracle being Oracle, this is not a simple process, as you have to patch the patching software before you can apply the patch. So first, we need to download a newer release of OPatch using MOS note 274526.1 otherwise known as patch 6880880.

We now have to apply this patch to the unzipped GI home before we launch gridSetup.sh:

cd $ORACLE_HOME
mv OPatch OPatch.bkp
unzip /download/oracle/p6880880_122010_Linux-x86-64.zip
cd OPatch

Next download the patch we really need. In this case it was patch 33803476 which was downloaded and staged on the first RAC node. Now we can launch gridSetup.sh and apply the patch to the GI home as part of running the setup script:

./gridSetup.sh -applyRU /download/oracle/19.15/33803476

That approach worked for installing Grid Infrastructure.

But when installing the database software the error appeared again.

This time I tried the second approach, which is to change the behavior of the scp executable in Linux:

The scp executable is renamed to scp.orig. Then a script named /usr/bin/scp is created containing the following:

/usr/bin/scp.orig -T $*

The new script is made executable by all.

[root@dsib0252]# cd /usr/bin
[root@dsib0252 bin]# mv scp scp.orig
[root@dsib0252 bin]# echo "/usr/bin/scp.orig -T \$*" > /usr/bin/scp
[root@dsib0252 bin]# chmod 555 /usr/bin/scp
[root@dsib0252 bin]# cat scp
/usr/bin/scp.orig -T $*

This change might have worked for the error from the Grid Infrastructure as well, but in the end I used both approaches.