[SSHD-852] Verification fails for hashed known host entry on non standard port generated by OpenSSH client

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.2.0
• Fix Version/s: 2.2.0
• Environment: Linux Mint 19
• Assignee: Lyor Goldstein
• Reporter: Stefan Verhoeven
• Created: 17/Oct/18 18:04
• Updated: 08/Jun/20 13:34
• Resolved: 19/Oct/18 17:29

Description

The Apache SshClient is unable to verify a known host entry that was made by the OpenSSH client when the entry is on a port other than 22.

 

I get the following exception

org.apache.sshd.common.SshException: Server key did not validate

 at org.apache.sshd.client.session.AbstractClientSession.checkKeys(AbstractClientSession.java:440)
...

 

The OpenSSH client will create a hash for `[host]:port` while Apache SshClient will check hashed entries for `host` (see https://git-wip-us.apache.org/repos/asf?p=mina-sshd.git;a=blob;f=sshd-common/src/main/java/org/apache/sshd/client/config/hosts/KnownHostEntry.java;h=91d61842373bb322b09198f551d6dfd095554677;hb=HEAD#l130[).|https://git-wip-us.apache.org/repos/asf?p=mina-sshd.git;a=blob;f=sshd-common/src/main/java/org/apache/sshd/client/config/hosts/KnownHostEntry.java;h=91d61842373bb322b09198f551d6dfd095554677;hb=HEAD#l130.] This difference will cause the correct known host entry to be marked as not a match which in turn causes the exception.

 

The error can be reproduced by setting up the a SSH server

rm ~/.ssh/known_hosts
docker run -d -p 2222:22 nlesc/xenon-ssh 
# Prime known hosts with hash entry, password=javagat
ssh xenon@localhost -p 10022 hostname

and then running the attached test.

 

I created a fix and tests at https://github.com/apache/mina-sshd/compare/master...NLeSC:hashed-known-host-port