Description of problem: It looks like that support for RHEL/CentOS 7 ciphers are incomplete. Version-Release number of selected component (if applicable): python2-paramiko-1.16.1-2.el7.noarch When connecting from CentOS7 to CentOS7 it will fails with: Unable to negotiate with X.X.X.X port XXXX: no matching key exchange method found. Their offer: diffie-hellman-group1-sha1,diffie-hellman-group14-sha1,diffie-hellman-group-exchange-sha1,diffie-hellman-group-exchange-sha256 [preauth] on the server side. This was found using pgadmin4 which will use python2-paramiko from epel.
Paramiko in RHEL/CentOS Extras and EPEL is version 2.1.1, changed some time ago when it was added to EL7 Extras. Are you not on the latest EL7?
It looks like the package was renamed from python2-paramiko to python-paramiko but without the replace tag. There exits 2 packages in EPEL python2-paramiko and python-paramiko. sudo yum info python2-paramiko: Installed Packages Name : python2-paramiko Arch : noarch Version : 1.16.1 Release : 2.el7 Size : 1.2 M Repo : installed From repo : epel Summary : SSH2 protocol library for python URL : https://github.com/paramiko/paramiko/ License : LGPLv2+ Description : : Paramiko (a combination of the esperanto words for "paranoid" and "friend") is : a module for python 2.3 or greater that implements the SSH2 protocol for secure : (encrypted and authenticated) connections to remote machines. Unlike SSL (aka : TLS), the SSH2 protocol does not require heirarchical certificates signed by a : powerful central authority. You may know SSH2 as the protocol that replaced : telnet and rsh for secure access to remote shells, but the protocol also : includes the ability to open arbitrary channels to remote services across an : encrypted tunnel. (This is how sftp works, for example.) : : Python 2 version. sudo yum info python-paramiko Available Packages Name : python-paramiko Arch : noarch Version : 2.1.1 Release : 9.el7 Size : 269 k Repo : updates/7/x86_64 Summary : SSH2 protocol library for python URL : https://github.com/paramiko/paramiko License : LGPLv2+ Description : : Paramiko (a combination of the esperanto words for "paranoid" and "friend") is : a module for python 2.3 or greater that implements the SSH2 protocol for secure : (encrypted and authenticated) connections to remote machines. Unlike SSL (aka : TLS), the SSH2 protocol does not require heirarchical certificates signed by a : powerful central authority. You may know SSH2 as the protocol that replaced : telnet and rsh for secure access to remote shells, but the protocol also : includes the ability to open arbitrary channels to remote services across an : encrypted tunnel. (This is how sftp works, for example.)
I'm not sure anything can be done now about this on the EPEL side of things.