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This package describes important Cygwin specific stuff concerning OpenSSH.
The binary package is usually built for recent Cygwin versions and might
not run on older versions. Please check for information
about current Cygwin releases.
Build instructions are at the end of the file.
Important change since 3.7.1p2-2:
The ssh-host-config file doesn't create the /etc/ssh_config and
/etc/sshd_config files from builtin here-scripts anymore, but it uses
skeleton files installed in /etc/defaults/etc.
Also it now tries hard to create appropriate permissions on files.
Same applies for ssh-user-config.
After creating the sshd service with ssh-host-config, it's advisable to
call ssh-user-config for all affected users, also already exising user
configurations. In the latter case, file and directory permissions are
checked and changed, if requireed to match the host configuration.
Important note for Windows 2003 Server users:
2003 Server has a funny new feature. When starting services under SYSTEM
account, these services have nearly all user rights which SYSTEM holds...
except for the "Create a token object" right, which is needed to allow
public key authentication :-(
There's no way around this, except for creating a substitute account which
has the appropriate privileges. Basically, this account should be member
of the administrators group, plus it should have the following user rights:
Create a token object
Logon as a service
Replace a process level token
Increase Quota
The ssh-host-config script asks you, if it should create such an account,
called "sshd_server". If you say "no" here, you're on your own. Please
follow the instruction in ssh-host-config exactly if possible. Note that
ssh-user-config sets the permissions on 2003 Server machines dependent of
whether a sshd_server account exists or not.
Important change since 3.4p1-2:
This version adds privilege separation as default setting, see
/usr/doc/openssh/README.privsep. According to that document the
privsep feature requires a non-privileged account called 'sshd'.
The new ssh-host-config file which is part of this version asks
to create 'sshd' as local user if you want to use privilege
separation. If you confirm, it creates that NT user and adds
the necessary entry to /etc/passwd.
On 9x/Me systems the script just sets UsePrivilegeSeparation to "no"
since that feature doesn't make any sense on a system which doesn't
differ between privileged and unprivileged users.
The new ssh-host-config script also adds the /var/empty directory
needed by privilege separation. When creating the /var/empty directory
by yourself, please note that in contrast to the README.privsep document
the owner sshould not be "root" but the user which is running sshd. So,
in the standard configuration this is SYSTEM. The ssh-host-config script
chowns /var/empty accordingly.
Important change since 3.0.1p1-2:
This version introduces the ability to register sshd as service on
Windows 9x/Me systems. This is done only when the options -D and/or
-d are not given.
Important change since 2.9p2:
Since Cygwin is able to switch user context without password beginning
with version 1.3.2, OpenSSH now allows to do so when it's running under
a version >= 1.3.2. Keep in mind that `ntsec' has to be activated to
allow that feature.
Important change since 2.3.0p1:
When using `ntea' or `ntsec' you now have to care for the ownership
and permission bits of your host key files and your private key files.
The host key files have to be owned by the NT account which starts
sshd. The user key files have to be owned by the user. The permission
bits of the private key files (host and user) have to be at least
rw------- (0600)!
Note that this is forced under `ntsec' only if the files are on a NTFS
filesystem (which is recommended) due to the lack of any basic security
features of the FAT/FAT32 filesystems.
If you are installing OpenSSH the first time, you can generate global config
files and server keys by running
Note that this binary archive doesn't contain default config files in /etc.
That files are only created if ssh-host-config is started.
If you are updating your installation you may run the above ssh-host-config
as well to move your configuration files to the new location and to
erase the files at the old location.
To support testing and unattended installation ssh-host-config got
some options:
usage: ssh-host-config [OPTION]...
--debug -d Enable shell's debug output.
--yes -y Answer all questions with "yes" automatically.
--no -n Answer all questions with "no" automatically.
--cygwin -c <options> Use "options" as value for CYGWIN environment var.
--port -p <n> sshd listens on port n.
--pwd -w <passwd> Use "pwd" as password for user 'sshd_server'.
Additionally ssh-host-config now asks if it should install sshd as a
service when running under NT/W2K. This requires cygrunsrv installed.
You can create the private and public keys for a user now by running
under the users account.
To support testing and unattended installation ssh-user-config got
some options as well:
usage: ssh-user-config [OPTION]...
--debug -d Enable shell's debug output.
--yes -y Answer all questions with "yes" automatically.
--no -n Answer all questions with "no" automatically.
--passphrase -p word Use "word" as passphrase automatically.
Install sshd as daemon via cygrunsrv.exe (recommended on NT/W2K), via inetd
(results in very slow deamon startup!) or from the command line (recommended
on 9X/ME).
If you start sshd as deamon via cygrunsrv.exe you MUST give the
"-D" option to sshd. Otherwise the service can't get started at all.
If starting via inetd, copy sshd to eg. /usr/sbin/in.sshd and add the
following line to your inetd.conf file:
ssh stream tcp nowait root /usr/sbin/in.sshd sshd -i
Moreover you'll have to add the following line to your
${SYSTEMROOT}/system32/drivers/etc/services file:
ssh 22/tcp #SSH daemon
Please note that OpenSSH does never use the value of $HOME to
search for the users configuration files! It always uses the
value of the pw_dir field in /etc/passwd as the home directory.
If no home diretory is set in /etc/passwd, the root directory
is used instead!
You may use all features of the CYGWIN=ntsec setting the same
way as they are used by Cygwin's login(1) port:
The pw_gecos field may contain an additional field, that begins
with (upper case!) "U-", followed by the domain and the username
separated by a backslash.
CAUTION: The SID _must_ remain the _last_ field in pw_gecos!
BTW: The field separator in pw_gecos is the comma.
The username in pw_name itself may be any nice name:
domuser::1104:513:John Doe,U-domain\user,S-1-5-21-...
Now you may use `domuser' as your login name with telnet!
This is possible additionally for local users, if you don't like
your NT login name ;-) You only have to leave out the domain:
locuser::1104:513:John Doe,U-user,S-1-5-21-...
Note that the CYGWIN=ntsec setting is required for public key authentication.
SSH2 server and user keys are generated by the `ssh-*-config' scripts
as well.
If you want to build from source, the following options to
configure are used for the Cygwin binary distribution:
--prefix=/usr \
--sysconfdir=/etc \
--libexecdir='${sbindir}' \
--localstatedir=/var \
--datadir='${prefix}/share' \
--mandir='${datadir}/man' \
If you want to create a Cygwin package, equivalent to the one
in the Cygwin binary distribution, install like this:
mkdir /tmp/cygwin-ssh
cd ${builddir}
make install DESTDIR=/tmp/cygwin-ssh
cd ${srcdir}/contrib/cygwin
make cygwin-postinstall DESTDIR=/tmp/cygwin-ssh
cd /tmp/cygwin-ssh
find * \! -type d | tar cvjfT my-openssh.tar.bz2 -
You must have installed the following packages to be able to build OpenSSH:
- zlib
- openssl-devel
If you want to build with --with-tcp-wrappers, you also need the package
- tcp_wrappers
If you want to build with --with-libedit, you also need the package
- libedit-devel
Please send requests, error reports etc. to
Have fun,
Corinna Vinschen
Cygwin Developer
Red Hat Inc.