X.509-SSH

This howto assumes you have a flavour of LINUX running on your machine!

SERVER (mainly intended for sysadmins and operators!)

INSTALLATION

• Download openssh sourcecode:

$ wget -c ftp://ftp.openbsd.org/pub/OpenBSD/OpenSSH/portable/openssh-5.3p1.tar.gz

• Download patch to support X.509 certificates for authenticaton:

$ wget -c http://www.roumenpetrov.info/openssh/x509-6.2.1/openssh-5.3p1+x509-6.2.1.diff.gz

• additional prerequisites:

"libc6" development packages, "zlib" development packages, "patch" binary

• On Ubuntu 8.04 LTS use:

$ sudo apt-get update $ sudo apt-get install libc6-dev zlib1g-dev patch

• On SLES10:

install "zlib-devel[-32bit]" and "openssl-devel[-32bit]"

• Extract openssh:

$ tar -xzf openssh-5.3p1.tar.gz

• Change into the new directory and apply the downloaded patch:

$ cd openssh-5.3p1 openssh-5.3p1/$ zcat <PATH_TO_PATCH>openssh-5.3p1+x509-6.2.1.diff.gz

• Configure and make:

Note: Commands enclosed in "[...]" are optional! See manpages for details.

openssh-5.3p1/$ [time] ./configure --prefix=<INSTALLATION-DIR> [2>&1 | tee configure.log] openssh-5.3p1/$ [time] make [2>&1 | tee make.log] openssh-5.3p1/$ [sudo] make install

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CLIENT (mainly intended for users)

INSTALLATION

• Download openssh sourcecode:

$ wget -c ftp://ftp.openbsd.org/pub/OpenBSD/OpenSSH/portable/openssh-5.3p1.tar.gz

• Download patch to support X.509 certificates for authenticaton from:

$ wget -c http://www.roumenpetrov.info/openssh/x509-6.2.1/openssh-5.3p1+x509-6.2.1.diff.gz

• additional prerequisites:

"libc6" development packages, "zlib" development packages, "patch" binary

• On Ubuntu 8.04 LTS use:

$ sudo apt-get update $ sudo apt-get install libc6-dev zlib1g-dev patch

• On SLES10:

install "zlib-devel[-32bit]" and "openssl-devel[-32bit]"

• Extract openssh:

$ tar -xzf openssh-5.3p1.tar.gz

• Change into the new directory and apply the downloaded patch:

$ cd openssh-5.3p1 openssh-5.3p1/$ zcat <PATH_TO_PATCH>openssh-5.3p1+x509-6.2.1.diff.gz

• Configure and make:

Note: Commands enclosed in "[...]" are optional! See manpages for details.

openssh-5.3p1/$ [time] ./configure [2>&1 | tee configure.log] openssh-5.3p1/$ [time] make [2>&1 | tee make.log]

• Take the following binaries:

openssh-5.3p1/$ cp ./ssh $HOME/bin [&& strip $HOME/bin/ssh] openssh-5.3p1/$ cp ./ssh-keygen $HOME/bin [&& strip $HOME/bin/ssh-keygen]

Note: Make sure that "$HOME/bin" is at the beginning of "$PATH" or call the created binaries directly.

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CONFIGURATION

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• Export a PKCS#12 keystore with your grid certificate and private key from your browser.

Note: This usually includes to set a password for the PKCS#12 keystore (referred to as the <KEYSTORE_PASSWD>).

• Export your certificate from the PKCS#12 keystore:

$ openssl pkcs12 -in <PKCS12_KEYSTORE> -clcerts -nokeys -out $HOME/.ssh/certificate.pem

Note: One has to enter the <KEYSTORE_PASSWD> once to unlock the PKCS#12 keystore for the export.

• Make sure the private key file is only accessible by you:

$ umask 0077

• Export private key from keystore:

$ openssl pkcs12 -in <PKCS12_KEYSTORE> -nocerts -out $HOME/.ssh/key.pem

Note: One has to enter the <KEYSTORE_PASSWD> once to unlock the PKCS#12 keystore for the export. Additionally one has to provide a password for the exported private key (two times).

• Create identity (file):

$ cat key.pem certificate.pem > $HOME/.ssh/x509_identity

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USAGE

• Log in to a remote system with X.509 SSH:

$ ssh -i $HOME/.ssh/x509_identity -l <YOUR_LOGIN_NAME> -p <PORT> <SERVER>

NOTICE:

For "laki" <PORT> is "443" and <SERVER> is "cl3fr1.hww.de". For "SX-9" <PORT> is "443" and <SERVER> is "yari.hww.de".

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PROBLEMS

• If there are problems that prevent you from login, please provide us with a full log of the authentication using the switch "-vvv":

$ ssh -vvv -i $HOME/.ssh/x509_identity -l <YOUR_LOGIN_NAME> -p <PORT> <SERVER> [&> full_auth.log]

Some common problems

• Symptom(s):
  • login impossible
  • messages in the full log of the authentication similar to the following messages:

[...]
debug2: key_type_from_name: unknown key type '-----END'
debug3: key_read: missing keytype
debug3: x509key_from_subject: 1 is not x509 key
debug3: key_from_blob(..., 279)
[...]
debug1: Next authentication method: publickey
debug1: Offering public key: x509_identity
debug3: send_pubkey_test
debug2: we sent a publickey packet, wait for reply
debug3: Wrote 368 bytes for a total of 1509
debug1: Authentications that can continue: publickey
debug2: we did not send a packet, disable method
debug1: No more authentication methods to try.
Permission denied (publickey).

• Problem:

You have created a public key out of the X.509 ssh private key using an unpatched "ssh-keygen".

• Possible solution:

You don't need to have a public key ready for accessing our systems. The public key is created automatically by your client during authentication. Therefore you can just delete this file (usually named like "x509_identity.pub").

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SEE ALSO

Readme for X.509 SSH v6.2.1