[SSHD-589] Auto-detect max. supported DH group exchange key size

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 1.0.0, 1.1.0
• Fix Version/s: 1.1.0

Environment

Fedora
$ java -version
openjdk version "1.8.0_60"
OpenJDK Runtime Environment (build 1.8.0_60-b27)
OpenJDK 64-Bit Server VM (build 25.60-b23, mixed mode)

Gentoo
$ java -version
openjdk version "1.8.0_60"
OpenJDK Runtime Environment (IcedTea 3.0.0pre06+ra9817b9f8a21) (Gentoo icedtea-3.0.0_pre06)
OpenJDK 64-Bit Server VM (build 25.60-b23, mixed mode)

Oracle
NOTE1: Disable SunEC provider at jre/lib/security/java.security to reproduce.
NOTE2: Install UnlimitedJCEPolicyJDK8
$ java -version
java version "1.8.0_65"
Java(TM) SE Runtime Environment (build 1.8.0_65-b17)
Java HotSpot(TM) 64-Bit Server VM (build 25.65-b01, mixed mode)

$ sshd -V
OpenSSH_6.9p1, OpenSSL 1.0.1k-fips 8 Jan 2015

Reproduce server: dev.gentoo.org (Kex only)

• Assignee: Lyor Goldstein
• Reporter: Alon Bar-Lev
• Created: 16/Nov/15 12:41
• Updated: 24/Nov/15 07:39
• Resolved: 22/Nov/15 05:21

Description

Using:
1. Same JVM to run test of 1.x and 0.x
2. The SunEC provider is not available.
3. BouncyCastle is not used.
4. The same Fedora-22 remote is accessed.

Using sshd-core-0.14 works, using sshd-core-1.0.1(master, and any 1.x) produces:
java.lang.IllegalStateException: Unable to negotiate key exchange for kex algorithms (client: diffie-hellman-group-exchange-sha1,diffie-hellman-group1-sha1 / server: [e-mail],ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha1)
at org.apache.sshd.common.session.AbstractSession.negotiate(AbstractSession.java:1334)
at org.apache.sshd.common.session.AbstractSession.handleKexInit(AbstractSession.java:478)
at org.apache.sshd.common.session.AbstractSession.doHandleMessage(AbstractSession.java:412)
at org.apache.sshd.common.session.AbstractSession.handleMessage(AbstractSession.java:361)

Per Lyor request, added some more debug information into master.

Attached:
1. Full test environment (test1.tar.gz) a directory per version, test using:
JAVA_OPTS="-Djava.util.logging.config.file=./logging.properties" ./ssh-test.sh --host=XXXX --password=XXXX --command="echo hello"
2. Full debug log of 0.14 and master.
3. Diff of logging.

This is a behaviour change in 1.x, so far we have failed to nail it.

Issue Links

• is broken by: SSHD-436 Use as much as possible common code for client and server KEX
• relates to: SSHD-567 Connection to Cisco caused java.security.InvalidAlgorithmParameterException
• relates to: SSHD-596 Support dhg14 by runtime DH key size detection similar to dhgex