Enable Legacy Cipher in Linux for SecureCRT

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SecureCRT version 3.1.2 has a limited selection of available ciphers. It is an old version of the client. In the past when the selections

  • Cipher: 3DES
  • MAC: MD5

where used, the client connected to the linux system sshd server (OpenSSH). SecureCRT is actually using the cipher "3des-cbc" specifically.

Supporting legacy ciphers for backwards compatibility is necessary to connect "ssh" with SecureCRT. The ssh server "sshd" ciphers can be configured via the file: 

vi /etc/ssh/sshd_config

See what ciphers are available on your system: 

ssh -Q cipher localhost

Even though 3des-cbc is enabled in the configuration, the client using 3des-cbc is rejected, as evidence in the log 

cat /var/log/auth.log

It turns out that number of version 2 ciphers have been disabled in the 6.7p1-1 release of openssh. Lets see what version of OpenSSH we have. 

dpkg-query -l|grep -i openssh

Debian Linux Jessie reports openssh-server 1:6.7p1-5+deb8u3 which has the following ciphers disabled: 3des-cbc,blowfish-cbc,cast128-cbc,arcfour,arcfour128,arcfour256,aes128-cbc,aes192-cbc,aes256-cbc,rijndael-cbc@lysator.liu.se

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