From 6fe4b2523e5f5591167c1e8a8e7574cfc34dac8d Mon Sep 17 00:00:00 2001 From: sgeorge Date: Tue, 19 Oct 2010 03:29:16 -0700 Subject: [PATCH] first edit --- docs/docs/newhandbook/sshserver/index.mdwn | 190 +++++++++++++++++++++ 1 file changed, 190 insertions(+) create mode 100644 docs/docs/newhandbook/sshserver/index.mdwn diff --git a/docs/docs/newhandbook/sshserver/index.mdwn b/docs/docs/newhandbook/sshserver/index.mdwn new file mode 100644 index 00000000..2154feba --- /dev/null +++ b/docs/docs/newhandbook/sshserver/index.mdwn @@ -0,0 +1,190 @@ +#SSH Server on DragonFly + +This document is very detailed so that a new user can be familiar with the environment. + +If you try to ssh to a newly installed dfly from another system you will get this error + +
+$ ssh root@172.16.50.62
+ssh: connect to host 172.16.50.62 port 22: Connection refused
+
+ +This is because sshd is not up and running on dfly. +At this point if you check /etc/ssh you will only have the following files + +
+# ls /etc/ssh
+blacklist.DSA-1024      blacklist.RSA-2048      ssh_config
+blacklist.DSA-2048      blacklist.RSA-4096      sshd_config
+blacklist.RSA-1024      moduli
+
+ +You don't have any SSH host keys generated for the system yet! + +When you start sshd for the first time it is best to start it through the "/etc/rc.d/sshd" script which will automatically generate the host keys. For this to work right you need to do the following steps + +1) Enable sshd in rc.conf + +
+#echo "sshd_enable=yes" >> /etc/rc.conf
+
+ +2) Start the sshd server using the rc script + +
+# /etc/rc.d/sshd start
+Generating public/private rsa1 key pair.
+Your identification has been saved in /etc/ssh/ssh_host_key.
+Your public key has been saved in /etc/ssh/ssh_host_key.pub.
+The key fingerprint is:
+........
+Generating public/private dsa key pair.
+Your identification has been saved in /etc/ssh/ssh_host_dsa_key.
+Your public key has been saved in /etc/ssh/ssh_host_dsa_key.pub.
+The key fingerprint is:
+........
+Starting sshd.
+
+ +Now if you go back and look in /etc/ssh you will find the SSH host key files too. + +
+# ls /etc/ssh
+blacklist.DSA-1024      moduli                  ssh_host_key.pub
+blacklist.DSA-2048      ssh_config              ssh_host_rsa_key
+blacklist.RSA-1024      ssh_host_dsa_key        ssh_host_rsa_key.pub
+blacklist.RSA-2048      ssh_host_dsa_key.pub    sshd_config
+blacklist.RSA-4096      ssh_host_key
+
+ +At this point if you try to ssh to the dfly you will get the following error + +
+$ ssh sgeorge@172.16.50.62
+The authenticity of host '172.16.50.62 (172.16.50.62)' can't be established.
+RSA key fingerprint is 46:77:28:c2:70:86:93:1a:23:32:5f:01:2c:80:de:de.
+Are you sure you want to continue connecting (yes/no)? yes
+Warning: Permanently added '172.16.50.62' (RSA) to the list of known hosts.
+Permission denied (publickey).
+
+ +This is because of the following configuration option in the default /"etc/ssh/sshd_config" file. + +
+# To disable tunneled clear text passwords, change to no here!
+# We disable cleartext passwords by default
+PasswordAuthentication no
+
+ +Change it to + +
+PasswordAuthentication yes
+
+
+and reload sshd configuration
+
+
+# /etc/rc.d/sshd reload
+Reloading sshd config files.
+

+
+Nowyou can login to the dragonfly system as a normal user.
+
+
+$ ssh sgeorge@172.16.50.62
+sgeorge at 172.16.50.62's password:
+Last login: Tue Oct 19 04:17:47 2010
+Copyright (c) 1980, 1983, 1986, 1988, 1990, 1991, 1993, 1994
+        The Regents of the University of California.  All rights reserved.
+
+DragonFly v2.7.3.1283.gfa568-DEVELOPMENT (GENERIC.MP) #3: Thu Oct 14
+12:01:24 IST 2010
+
+....
+

+
+But if you try to login by SSH as root you will get the following error.
+
+
+$ ssh root at 172.16.50.62
+root at 172.16.50.62's password:
+Permission denied, please try again.
+

+
+If you investigate the log of the dragonfly system "/var/log/auth.log" you will find a line similar to
+
+
+Oct 19 07:29:36 dfly-vmsrv sshd[17269]: Failed password for root from 172.16.2.0 port 56447 ssh2
+

+
+even if you typed the right password for root.
+
+It is because of the following configuration option in the default /"etc/ssh/sshd_config" file
+
+
+# only allow root logins via public key pair
+PermitRootLogin without-password
+

+
+which allowes only SSH key based authentication as root.
+
+If you change it to
+
+
+PermitRootLogin yes
+

+
+and reload sshd configuration
+
+
+# /etc/rc.d/sshd reload
+Reloading sshd config files.
+

+
+you can login as root
+
+
+$ ssh root@172.16.50.62
+root at 172.16.50.62's password:
+Last login: Fri Oct  8 12:22:40 2010
+Copyright (c) 1980, 1983, 1986, 1988, 1990, 1991, 1993, 1994
+        The Regents of the University of California.  All rights reserved.
+
+DragonFly v2.7.3.1283.gfa568-DEVELOPMENT (GENERIC.MP) #3: Thu Oct 14
+12:01:24 IST 2010
+
+Welcome to DragonFly!
+......
+

+
+Now in the "/var/log/auth.log" you will find a line similar to
+
+
+Oct 19 07:30:32 dfly-vmsrv sshd[17894]: Accepted password for root from 172.16.2.0 port 56468 ssh2
+

+
+
WARNING :
  It is not advisable to allow Root Login with password especially if your System is connected to the Internet unless you use Very Strong Passwords. You could be a victim of [ssh password based brute force attacks](http://en.wikipedia.org/wiki/Password_cracking#Brute_force_attack). If you are victim of one such attack you can find entries like the following in your "/var/log/auth.log file".
+
+
+Oct 18 18:54:54 cross sshd[9783]: Invalid user maryse from 218.248.26.6
+Oct 18 18:54:54 cross sshd[9781]: input_userauth_request: invalid user maryse
+Oct 18 18:54:54 cross sshd[9783]: Failed password for invalid user maryse from 218.248.26.6 port 34847 ssh2
+Oct 18 18:54:54 cross sshd[9781]: Received disconnect from 218.248.26.6: 11: Bye Bye
+Oct 18 18:54:55 cross sshd[27641]: Invalid user may from 218.248.26.6
+Oct 18 18:54:55 cross sshd[3450]: input_userauth_request: invalid user may
+Oct 18 18:54:55 cross sshd[27641]: Failed password for invalid user may from 218.248.26.6 port 34876 ssh2
+Oct 18 18:54:55 cross sshd[3450]: Received disconnect from 218.248.26.6: 11: Bye Bye
+Oct 18 18:54:56 cross sshd[8423]: Invalid user admin from 218.248.26.6
+Oct 18 18:54:56 cross sshd[3131]: input_userauth_request: invalid user admin
+Oct 18 18:54:56 cross sshd[8423]: Failed password for invalid user admin from 218.248.26.6 port 34905 ssh2
+Oct 18 18:54:56 cross sshd[3131]: Received disconnect from 218.248.26.6: 11: Bye Bye
+Oct 18 18:54:57 cross sshd[7373]: Invalid user admin from 218.248.26.6
+Oct 18 18:54:57 cross sshd[28059]: input_userauth_request: invalid user admin
+Oct 18 18:54:57 cross sshd[7373]: Failed password for invalid user admin from 218.248.26.6 port 34930 ssh2
+Oct 18 18:54:57 cross sshd[28059]: Received disconnect from 218.248.26.6: 11: Bye Bye
+Oct 18 18:54:58 cross sshd[12081]: Invalid user admin from 218.248.26.6
+Oct 18 18:54:58 cross sshd[22416]: input_userauth_request: invalid user admin
+Oct 18 18:54:58 cross sshd[12081]: Failed password for invalid user admin from 218.248.26.6 port 34958 ssh2
+Oct 18 18:54:58 cross sshd[22416]: Received disconnect from 218.248.26.6: 11: Bye Bye
+

-- 
2.41.0