You signed in with another tab or window. Reload to refresh your session.You signed out in another tab or window. Reload to refresh your session.You switched accounts on another tab or window. Reload to refresh your session.Dismiss alert
It is a FREE version of the SSH protocol suite of network connectivity tools. OpenSSH encrypts all traffic (including passwords) to effectively eliminate eavesdropping, connection hijacking, and other network-level attacks. Additionally, OpenSSH provides a plethora of secure tunneling capabilities, as well as a variety of authentication methods.
615
615
616
-
It helps to provide secure encrypted communications between two untrusted hosts over an insecure network (such as the internet).
616
+
It helps to provide secure encrypted communications between two un-trusted hosts over an insecure network (such as the internet).
617
617
618
618
It includes both the server-side components and the client-side suite of programs
619
619
@@ -623,12 +623,12 @@ The server side includes the secure shell daemon (`sshd`). `sshd` is the daemon
623
623
624
624
It forks a new daemon for each incoming connection. The forked daemons handle key exchange, encryption, authentication, command execution, and data exchange. According to sshd’s man page, `sshd` works as follows:
625
625
626
-
The OpenSSH SSH daemon supports SSH protocol 2 only. Each host has a host-specific key, used to identify the host. Whenever a client connects, the daemon responds
627
-
with its public host key. The client compares the host key against its own database to verify that it has not changed. Forward security is provided through a Diffie-Hellman key agreement. This key agreement results in a shared session key. The rest of the session is encrypted using a symmetric cipher.
626
+
The OpenSSH SSH daemon supports SSH protocol 2 only. Each host has a host-specific key, used to identify the host. Whenever a client connects, the daemon responds
627
+
with its public host key. The client compares the host key against its own database to verify that it has not changed. Forward security is provided through a Diffie-Hellman key agreement. This key agreement results in a shared session key. The rest of the session is encrypted using a symmetric cipher.
628
628
629
-
The client selects the encryption algorithm to use from those offered by the server. Additionally, session integrity is provided through a cryptographic message authentication code (hmac-md5, hmac-sha1, umac-64, umac-128, hmac-sha2-256 or hmac-sha2-512).
629
+
The client selects the encryption algorithm to use from those offered by the server. Additionally, session integrity is provided through a cryptographic message authentication code (hmac-md5, hmac-sha1, umac-64, umac-128, hmac-sha2-256 or hmac-sha2-512).
630
630
631
-
Finally, the server and the client enter an authentication dialog. The client tries to authenticate itself using host-based authentication, public key authentication,
631
+
Finally, the server and the client enter an authentication dialog. The client tries to authenticate itself using host-based authentication, public key authentication,
632
632
GSSAPI authentication, challenge-response authentication, or password authentication.
633
633
634
634
The SSH2 protocol implemented in OpenSSH is standardized by the “IETF secsh” working group
@@ -639,7 +639,7 @@ The client's suite of programs include `ssh`. This is a program used for logging
639
639
640
640
## Exercise 5
641
641
642
-
### sshd
642
+
### `sshd`
643
643
644
644
Some exercises covering the `sshd` server daemon.
645
645
@@ -669,7 +669,7 @@ Most Linux systems out of the box already have the OpenSSH server configured and
669
669
670
670
### `sshd_config`
671
671
672
-
1. Open up the ssh server’s config file with any pager and study it. Type:
672
+
1. Open up the SSH server’s configuration file with any pager and study it. Type:
673
673
674
674
```
675
675
[root@serverXY root]# less /etc/ssh/sshd_config
@@ -967,7 +967,7 @@ The public is store in a file with the same file name as the private key but wit
967
967
Created directory '/home/ying/.ssh'.
968
968
```
969
969
970
-
You'll be prompted twice to enter a passphrase. Input a good and reasonably difficult to guess passphrase. Press <kbd>ENTER</kbd> afte
970
+
You'll be prompted twice to enter a passphrase. Input a good and reasonably difficult to guess passphrase. Press <kbd>ENTER</kbd> after each prompt.
971
971
972
972
```bash
973
973
Enter passphrase (empty for no passphrase): *****
@@ -983,7 +983,7 @@ The public is store in a file with the same file name as the private key but wit
983
983
...<SNIP>...
984
984
```
985
985
986
-
After successful completion, you'll see a message stating that your identififcation and public keys have been saved under the `/home/ying/.ssh/` directory.
986
+
After successful completion, you'll see a message stating that your identification and public keys have been saved under the `/home/ying/.ssh/` directory.
987
987
988
988
3. cd to your `~/.ssh/` directory. List the files in the directory.
989
989
@@ -1067,15 +1067,15 @@ In this exercise you will learn how to configure the agent such that you wont ha
1067
1067
1068
1068
Take note of the value of the process ID (PID) of the agent in your output.
1069
1069
1070
-
3. Run the ssh-add program to list the fingerprints of all [public/private] identities currently
1070
+
3. Run the `ssh-add` program to list the fingerprints of all [public/private] identities currently
1071
1071
represented by the agent. TYpe:
1072
1072
1073
1073
```bash
1074
1074
[ying@localhost ~]$ ssh-add -l
1075
1075
The agent has no identities.
1076
1076
```
1077
1077
1078
-
You shoudn't yet have any identities listed.
1078
+
You shouldn't yet have any identities listed.
1079
1079
1080
1080
4. Use the `ssh-add` program without any options to add your keys to the agent you launched above. Type:
1081
1081
@@ -1089,26 +1089,26 @@ In this exercise you will learn how to configure the agent such that you wont ha
6. Now as the user *ying*, try connecting remotly to serverPR and run a simple test command.
1100
-
1101
-
Assuming you've done everything correctly till this point regarding setting up and storing the relevant keys, has done correctly till this point you should NOT be prompted for a password or passphrase. Type:
1099
+
6. Now as the user *ying*, try connecting remotely to serverPR and run a simple test command.
1102
1100
1101
+
Assuming you've done everything correctly till this point regarding setting up and storing the relevant keys, has done correctly till this point you should NOT be prompted for a password or passphrase. Type:
1102
+
1103
1103
```
1104
1104
[ying@serverXY .ssh]$ ssh serverPR 'ls /tmp'
1105
1105
```
1106
-
1107
-
7. If you are done and no longer in need of the services of the ssh-agent or you simply want to revert back to key based authentication you can delete all the [private/public] identities from the agent. Type:
1106
+
1107
+
7. If you are done and no longer in need of the services of the `ssh-agent` or you simply want to revert back to key based authentication you can delete all the [private/public] identities from the agent. Type:
0 commit comments