OpenBSD Journal

OpenSSH 2.5.1 released

Contributed by Dengue on from the OpenSSH dept.

A Nony Mouse writes : "It looks like OpenSSH 2.5.1 is out, which includes an sftp program and various other fixes and additions. Get it via CVS or ftp. "

OpenSSH 2.5.1 is also now in 2.8-stable. Read below for a list of new features and fixes:

Important Changes:

1) Features added to the implementation of the SSH 2 protocol:

    * agent forwarding
    * support for -R forwarding
    * RSA host and userkeys
    * extended support for older SSH 2 protocol implementations

    OpenSSH still lacks support for rekeying, so you have to turn off
    rekeying if your server tries to force this feature.

    The next release of OpenSSH will probably support rekeying.

2) Damien Miller contributed an interactive sftp client.

    The sftp client works for both SSH protocol versions.

3) David Mazieres' ssh-keyscan has been added to the OpenSSH distribution.

4) Now there are three types of keys in OpenSSH:

    RSA1 is used by the SSH 1 protocol only,
    RSA and DSA keys are used by the SSH 2 protocol implementation.

    You can generate RSA keys for use with SSH 2 protocol with:

        $ ssh-keygen -t rsa -f /etc/ssh_host_rsa_key

        To use RSA or DSA keys in SSH 2 protocol, simply
        add the public keys to the .ssh/authorised_keys2 file.

    IdentityFile2, HostDsaKey and DSAAuthentication are obsolete:

    You can use multiple IdentityFile and HostKey options instead, e.g
        HostKey /etc/ssh_host_key
        HostKey /etc/ssh_host_dsa_key
        HostKey /etc/ssh_host_rsa_key
    in /etc/sshd_config

    The option DSAAuthentication has been replaced by PubkeyAuthentication.

    Fingerprinting works for all types of keys:

        $ ssh-keygen -l -f $HOME/.ssh/{authorized_keys,known_hosts}{,2}

5) Important changes in the implementation of SSH 1 protocol:

    The OpenSSH server does not require a privileged source port for
    RhostsRsaAuthentication, since it adds no additional security.

    Interoperation with SSH 1.4 protocol

6) New option HostKeyAlias

    This option allows the user to record the host key under a
    different name. This is useful for tunneling over
    forwarded connections or if you run multiple sshd's on
    different ports on the same machine.

    Alternatively you can use the UserKnownHostsFile or 
    UserKnownHostsFile2 options to specify seperate host key
    files for the connection.

7) The ReverseMappingCheck is now optional in sshd_config.

    If you combine this with the 'sshd -u0' option the server
    will not do DNS lookups when a client connects.

8) Stricter Hostkey Checking

9) Option Change Summary:

    a) New or changed:


        HostkeyAlias        (Client only)

        Banner              (Server only)
        ReverseMappingCheck (Server only)

        PermitRootLogin     {yes,without-password,forced-commands-only,no}

        {Allow,Deny}Groups  now support supplementary groups

        sshd -D             for monitoring scripts or inittab
        ssh -t              multiple -t force tty allocation

    b) Obsolete:

        DsaAuthentication   (use PubkeyAuthentication instead)
        HostDsaKey          (use HostKey)
        Identityfile2       (use Identityfile or -i)
        SkeyAuthentication  (use ChallengeResponseAuthentication)
        TisAuthentication   (use ChallengeResponseAuthentication)

OpenSSH is brought to you by Markus Friedl, Niels Provos, Theo de Raadt,
Kevin Steves, Damien Miller and Ben Lindstrom.

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