1 #SSH Server on DragonFly
3 This document is very detailed so that a new user can be familiar with the environment.
5 If you try to ssh to a newly installed dfly from another system you will get this error
8 $ ssh root@172.16.50.62
9 ssh: connect to host 172.16.50.62 port 22: Connection refused
11 This is because sshd is not up and running on dfly.
12 At this point if you check /etc/ssh you will only have the following files
16 blacklist.DSA-1024 blacklist.RSA-2048 ssh_config
17 blacklist.DSA-2048 blacklist.RSA-4096 sshd_config
18 blacklist.RSA-1024 moduli
20 You don't have any SSH host keys generated for the system yet!
22 When you start sshd for the first time it is best to start it through the <b>"/etc/rc.d/sshd"</b> script which will automatically generate the host keys. For this to work right you need to do the following steps
24 1) Enable sshd in rc.conf
26 #echo "sshd_enable=yes" >> /etc/rc.conf
28 2) Start the sshd server using the rc script
31 # /etc/rc.d/sshd start
32 Generating public/private rsa1 key pair.
33 Your identification has been saved in /etc/ssh/ssh_host_key.
34 Your public key has been saved in /etc/ssh/ssh_host_key.pub.
35 The key fingerprint is:
37 Generating public/private dsa key pair.
38 Your identification has been saved in /etc/ssh/ssh_host_dsa_key.
39 Your public key has been saved in /etc/ssh/ssh_host_dsa_key.pub.
40 The key fingerprint is:
44 Now if you go back and look in /etc/ssh you will find the SSH host key files too.
48 blacklist.DSA-1024 moduli ssh_host_key.pub
49 blacklist.DSA-2048 ssh_config ssh_host_rsa_key
50 blacklist.RSA-1024 ssh_host_dsa_key ssh_host_rsa_key.pub
51 blacklist.RSA-2048 ssh_host_dsa_key.pub sshd_config
52 blacklist.RSA-4096 ssh_host_key
55 At this point if you try to ssh to the dfly you will get the following error
58 $ ssh sgeorge@172.16.50.62
59 The authenticity of host '172.16.50.62 (172.16.50.62)' can't be established.
60 RSA key fingerprint is 46:77:28:c2:70:86:93:1a:23:32:5f:01:2c:80:de:de.
61 Are you sure you want to continue connecting (yes/no)? yes
62 Warning: Permanently added '172.16.50.62' (RSA) to the list of known hosts.
63 Permission denied (publickey).
65 This is because of the following configuration option in the default **"/etc/ssh/sshd_config"** file.
68 # To disable tunneled clear text passwords, change to no here!
69 # We disable cleartext passwords by default
70 PasswordAuthentication no
75 PasswordAuthentication yes
78 and reload **sshd** configuration
81 # /etc/rc.d/sshd reload
82 Reloading sshd config files.
84 Nowyou can login to the dragonfly system as a normal user.
86 $ ssh sgeorge@172.16.50.62
87 sgeorge at 172.16.50.62's password:
88 Last login: Tue Oct 19 04:17:47 2010
89 Copyright (c) 1980, 1983, 1986, 1988, 1990, 1991, 1993, 1994
90 The Regents of the University of California. All rights reserved.
92 DragonFly v2.7.3.1283.gfa568-DEVELOPMENT (GENERIC.MP) #3: Thu Oct 14 12:01:24 IST 2010
96 But if you try to login by SSH as root you will get the following error.
98 $ ssh root at 172.16.50.62
99 root at 172.16.50.62's password:
100 Permission denied, please try again.
102 If you investigate the log of the dragonfly system <b>"/var/log/auth.log"</b> you will find a line similar to
105 Oct 19 07:29:36 dfly-vmsrv sshd[17269]: Failed password for root from 172.16.2.0 port 56447 ssh2
107 even if you typed the right password for root.
109 It is because of the following configuration option in the default **"/etc/ssh/sshd_config"** file
111 # only allow root logins via public key pair
112 PermitRootLogin without-password
114 which allowes only SSH key based authentication as root.
121 and reload **sshd** configuration
123 # /etc/rc.d/sshd reload
124 Reloading sshd config files.
126 you can login as **root**
128 $ ssh root@172.16.50.62
129 root at 172.16.50.62's password:
130 Last login: Fri Oct 8 12:22:40 2010
131 Copyright (c) 1980, 1983, 1986, 1988, 1990, 1991, 1993, 1994
132 The Regents of the University of California. All rights reserved.
134 DragonFly v2.7.3.1283.gfa568-DEVELOPMENT (GENERIC.MP) #3: Thu Oct 14 12:01:24 IST 2010
136 Welcome to DragonFly!
139 Now in the **"/var/log/auth.log" ** you will find a line similar to
142 Oct 19 07:30:32 dfly-vmsrv sshd[17894]: Accepted password for root from 172.16.2.0 port 56468 ssh2
146 ** 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"****.
148 Oct 18 18:54:54 cross sshd[9783]: Invalid user maryse from 218.248.26.6
149 Oct 18 18:54:54 cross sshd[9781]: input_userauth_request: invalid user maryse
150 Oct 18 18:54:54 cross sshd[9783]: Failed password for invalid user maryse from 218.248.26.6 port 34847 ssh2
151 Oct 18 18:54:54 cross sshd[9781]: Received disconnect from 218.248.26.6: 11: Bye Bye
152 Oct 18 18:54:55 cross sshd[27641]: Invalid user may from 218.248.26.6
153 Oct 18 18:54:55 cross sshd[3450]: input_userauth_request: invalid user may
154 Oct 18 18:54:55 cross sshd[27641]: Failed password for invalid user may from 218.248.26.6 port 34876 ssh2
155 Oct 18 18:54:55 cross sshd[3450]: Received disconnect from 218.248.26.6: 11: Bye Bye
156 Oct 18 18:54:56 cross sshd[8423]: Invalid user admin from 218.248.26.6
157 Oct 18 18:54:56 cross sshd[3131]: input_userauth_request: invalid user admin
158 Oct 18 18:54:56 cross sshd[8423]: Failed password for invalid user admin from 218.248.26.6 port 34905 ssh2
159 Oct 18 18:54:56 cross sshd[3131]: Received disconnect from 218.248.26.6: 11: Bye Bye
160 Oct 18 18:54:57 cross sshd[7373]: Invalid user admin from 218.248.26.6
161 Oct 18 18:54:57 cross sshd[28059]: input_userauth_request: invalid user admin
162 Oct 18 18:54:57 cross sshd[7373]: Failed password for invalid user admin from 218.248.26.6 port 34930 ssh2
163 Oct 18 18:54:57 cross sshd[28059]: Received disconnect from 218.248.26.6: 11: Bye Bye
164 Oct 18 18:54:58 cross sshd[12081]: Invalid user admin from 218.248.26.6
165 Oct 18 18:54:58 cross sshd[22416]: input_userauth_request: invalid user admin
166 Oct 18 18:54:58 cross sshd[12081]: Failed password for invalid user admin from 218.248.26.6 port 34958 ssh2
167 Oct 18 18:54:58 cross sshd[22416]: Received disconnect from 218.248.26.6: 11: Bye Bye