~ubuntu-branches/ubuntu/feisty/openssh/feisty-security

1. Prerequisites

----------------

You will need working installations of Zlib and OpenSSL.

Zlib 1.1.4 or 1.2.1.2 or greater (ealier 1.2.x versions have problems):

http://www.gzip.org/zlib/

OpenSSL 0.9.6 or greater:

http://www.openssl.org/

(OpenSSL 0.9.5a is partially supported, but some ciphers (SSH protocol 1

Blowfish) do not work correctly.)

OpenSSH can utilise Pluggable Authentication Modules (PAM) if your system

supports it. PAM is standard on Redhat and Debian Linux, Solaris and

HP-UX 11.

NB. If you operating system supports /dev/random, you should configure

OpenSSL to use it. OpenSSH relies on OpenSSL's direct support of

/dev/random. If you don't you will have to rely on ssh-rand-helper, which

is inferior to a good kernel-based solution.

PAM:

http://www.kernel.org/pub/linux/libs/pam/

If you wish to build the GNOME passphrase requester, you will need the GNOME

libraries and headers.

GNOME:

http://www.gnome.org/

Alternatively, Jim Knoble <jmknoble@pobox.com> has written an excellent X11

passphrase requester. This is maintained separately at:

http://www.jmknoble.net/software/x11-ssh-askpass/

PRNGD:

If your system lacks Kernel based random collection, the use of Lutz

Jaenicke's PRNGd is recommended.

http://www.aet.tu-cottbus.de/personen/jaenicke/postfix_tls/prngd.html

EGD:

The Entropy Gathering Daemon (EGD) is supported if you have a system which

lacks /dev/random and don't want to use OpenSSH's internal entropy collection.

http://www.lothar.com/tech/crypto/

S/Key Libraries:

If you wish to use --with-skey then you will need the library below

installed.  No other S/Key library is currently known to be supported.

http://www.sparc.spb.su/solaris/skey/

LibEdit:

sftp now supports command-line editing via NetBSD's libedit.  If your

platform has it available natively you can use that, alternatively

you might try these multi-platform ports:

http://www.thrysoee.dk/editline/

http://sourceforge.net/projects/libedit/

2. Building / Installation

--------------------------

To install OpenSSH with default options:

./configure

make

make install

This will install the OpenSSH binaries in /usr/local/bin, configuration files

in /usr/local/etc, the server in /usr/local/sbin, etc. To specify a different

installation prefix, use the --prefix option to configure:

./configure --prefix=/opt

make

make install

Will install OpenSSH in /opt/{bin,etc,lib,sbin}. You can also override

specific paths, for example:

./configure --prefix=/opt --sysconfdir=/etc/ssh

make

make install

This will install the binaries in /opt/{bin,lib,sbin}, but will place the

configuration files in /etc/ssh.

If you are using Privilege Separation (which is enabled by default)

then you will also need to create the user, group and directory used by

sshd for privilege separation.  See README.privsep for details.

If you are using PAM, you may need to manually install a PAM control

file as "/etc/pam.d/sshd" (or wherever your system prefers to keep

them).  Note that the service name used to start PAM is __progname,

which is the basename of the path of your sshd (e.g., the service name

for /usr/sbin/osshd will be osshd).  If you have renamed your sshd

executable, your PAM configuration may need to be modified.

A generic PAM configuration is included as "contrib/sshd.pam.generic",

you may need to edit it before using it on your system. If you are

using a recent version of Red Hat Linux, the config file in

contrib/redhat/sshd.pam should be more useful.  Failure to install a

valid PAM file may result in an inability to use password

authentication.  On HP-UX 11 and Solaris, the standard /etc/pam.conf

configuration will work with sshd (sshd will match the other service

name).

There are a few other options to the configure script:

--with-pam enables PAM support. If PAM support is compiled in, it must

also be enabled in sshd_config (refer to the UsePAM directive).

--with-prngd-socket=/some/file allows you to enable EGD or PRNGD

support and to specify a PRNGd socket. Use this if your Unix lacks

/dev/random and you don't want to use OpenSSH's builtin entropy

collection support.

--with-prngd-port=portnum allows you to enable EGD or PRNGD support

and to specify a EGD localhost TCP port. Use this if your Unix lacks

/dev/random and you don't want to use OpenSSH's builtin entropy

collection support.

--with-lastlog=FILE will specify the location of the lastlog file.

./configure searches a few locations for lastlog, but may not find

it if lastlog is installed in a different place.

--without-lastlog will disable lastlog support entirely.

--with-osfsia, --without-osfsia will enable or disable OSF1's Security

Integration Architecture.  The default for OSF1 machines is enable.

--with-skey=PATH will enable S/Key one time password support. You will

need the S/Key libraries and header files installed for this to work.

--with-tcp-wrappers will enable TCP Wrappers (/etc/hosts.allow|deny)

support. You will need libwrap.a and tcpd.h installed.

--with-md5-passwords will enable the use of MD5 passwords. Enable this

if your operating system uses MD5 passwords and the system crypt() does

not support them directly (see the crypt(3/3c) man page). If enabled, the

resulting binary will support both MD5 and traditional crypt passwords.

--with-utmpx enables utmpx support. utmpx support is automatic for

some platforms.

--without-shadow disables shadow password support.

--with-ipaddr-display forces the use of a numeric IP address in the

$DISPLAY environment variable. Some broken systems need this.

--with-default-path=PATH allows you to specify a default $PATH for sessions

started by sshd. This replaces the standard path entirely.

--with-pid-dir=PATH specifies the directory in which the ssh.pid file is

created.

--with-xauth=PATH specifies the location of the xauth binary

--with-ssl-dir=DIR allows you to specify where your OpenSSL libraries

are installed.

--with-4in6 Check for IPv4 in IPv6 mapped addresses and convert them to

real (AF_INET) IPv4 addresses. Works around some quirks on Linux.

--with-opensc=DIR

--with-sectok=DIR allows for OpenSC or sectok smartcard libraries to

be used with OpenSSH.  See 'README.smartcard' for more details.

If you need to pass special options to the compiler or linker, you

can specify these as environment variables before running ./configure.

For example:

CFLAGS="-O -m486" LDFLAGS="-s" LIBS="-lrubbish" LD="/usr/foo/ld" ./configure

3. Configuration

----------------

The runtime configuration files are installed by in ${prefix}/etc or

whatever you specified as your --sysconfdir (/usr/local/etc by default).

The default configuration should be instantly usable, though you should

review it to ensure that it matches your security requirements.

To generate a host key, run "make host-key". Alternately you can do so

manually using the following commands:

    ssh-keygen -t rsa1 -f /etc/ssh/ssh_host_key -N ""

    ssh-keygen -t rsa -f /etc/ssh/ssh_host_rsa_key -N ""

    ssh-keygen -t dsa -f /etc/ssh/ssh_host_dsa_key -N ""

Replacing /etc/ssh with the correct path to the configuration directory.

(${prefix}/etc or whatever you specified with --sysconfdir during

configuration)

If you have configured OpenSSH with EGD support, ensure that EGD is

running and has collected some Entropy.

For more information on configuration, please refer to the manual pages

for sshd, ssh and ssh-agent.

4. (Optional) Send survey

-------------------------

$ make survey

[check the contents and make sure there's no sensitive information]

$ make send-survey

This will send configuration information for the currently configured

host to a survey address.  This will help determine which configurations

are actually in use, and what valid combinations of configure options

exist.  The raw data is available only to the OpenSSH developers, however

summary data may be published.

5. Problems?

------------

If you experience problems compiling, installing or running OpenSSH.

Please refer to the "reporting bugs" section of the webpage at

http://www.openssh.com/

$Id: INSTALL,v 1.70 2005/04/24 07:52:23 dtucker Exp $