SSH cannot connect to old servers/devices/switches/routers/Cisco/Juniper Unable to negotiate with 192.168.20.2 port 22: no matching key exchange method found. Their offer: diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hell
A lot of older devices either support telnet or very old SSH keyx algorithms which are insecure and disabled by all newer/modern SSH clients for security reasons. However, sometimes you may be on a LAN via VPNor some other secured network or for whatever reason, absolutely, need to connect to this device and sometimes old/embedded devices may not be possible to update to a newer SSH server.
If you run into this you may be using a modern/newer SSH client and get thi........
Unable to negotiate with 192.168.1.99 port 22: no matching host key type found. Their offer: ssh-dss Solution
ssh rtt@192.168.1.199
Unable to negotiate with 192.168.1.99 port 22: no matching host key type found. Their offer: ssh-dss
It looks like the DSS option is not considered secure so when connecting from newer Linux systems to an older one you will get the above error.
It can be fixed (but you should consider upgrading your SSH daemon):
ssh -oHostKeyAlgorithms=+ssh-dss rtt@192.168.1.199........
Avocent 8020 KVM Java Icedtea Viewer
This command in Debian/Ubuntu/Mint will get everything need installed for most Java based KVM viewers:
sudo apt install icedtea-netx
The following additional packages will be installed:
ca-certificates-java icedtea-netx-common openjdk-8-jre openjdk-8-jre-headless
It seems every other updated version of Java or Icedtea breaks things and I will save the frustration of Java for another post.........