Weitere Beispiele und Screenshots 20.11.2024

20241120/dbs-20241120.tex

@@ -205,11 +205,14 @@
 
   \textbf{UDP-Protokolle}
   \begin{itemize}
+    \item
+      Video- und Audio-Übertragung (z.\,B.\ \file{mumble})
+    \smallskip
     \item
       \textbf{DNS} (auch TCP)\\
       Schnelle Abfrage von Informationen, insbesondere:\\
       Die zu einem Rechner-Namen gehörige IP-Adresse herausfinden
-    \medskip
+    \smallskip
     \item
       \textbf{DHCP}\\
       benutzbare IP-Adresse (und weitere Informationen) bei einem Server erfragen
@@ -221,6 +224,7 @@
   \begin{itemize}
     \item
       Informationsaustausch zwischen Rechnern zur Verwaltung des Netzwerks selbst
+    \smallskip
     \item
       Beispiel: \lstinline[style=cmd]{ping}
   \end{itemize}
@@ -320,7 +324,9 @@
       \lstinline[style=cmd]{ssh -X},
       \lstinline[style=cmd]{ssh -Y}: X11-Forwarding\\
       Warnung: Der entfernte Rechner bekommt Zugriff auf den X-Server\\
-      und kann insbesondere Tastatureingaben mitlesen!
+      und kann insbesondere Tastatureingaben mitlesen!\\
+      Für Details siehe: X11-SECURITY-Erweiterungen:\\
+      \url{https://www.x.org/wiki/Development/Documentation/Security/}
     \pause
     \bigskip
     \item

20241120/dns-01.txt

+cassini/home/peter/bo/2024ws/dbs/20241120> ping ngc224.gerwinski.de
+PING m31.gerwinski.de (88.198.170.60) 56(84) bytes of data.
+64 bytes from mx1.gerwinski.de (88.198.170.60): icmp_seq=1 ttl=55 time=12.6 ms
+64 bytes from mx1.gerwinski.de (88.198.170.60): icmp_seq=2 ttl=55 time=15.0 ms
+64 bytes from mx1.gerwinski.de (88.198.170.60): icmp_seq=3 ttl=55 time=13.3 ms
+^C
+--- m31.gerwinski.de ping statistics ---
+3 packets transmitted, 3 received, 0% packet loss, time 2002ms
+rtt min/avg/max/mdev = 12.649/13.646/14.958/0.968 ms
+cassini/home/peter/bo/2024ws/dbs/20241120> cat /etc/resolv.conf
+# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
+#     DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
+# 127.0.0.53 is the systemd-resolved stub resolver.
+# run "resolvectl status" to see details about the actual nameservers.
+
+nameserver 10.128.2.2
+nameserver 10.128.2.3
+search hs-bochum.de
+cassini/home/peter/bo/2024ws/dbs/20241120> host ngc224.gerwinski.de
+ngc224.gerwinski.de is an alias for m31.gerwinski.de.
+m31.gerwinski.de has address 88.198.170.60
+m31.gerwinski.de mail is handled by 10 mx2.gerwinski.de.
+cassini/home/peter/bo/2024ws/dbs/20241120> host mx2.gerwinski.de
+mx2.gerwinski.de has address 88.198.170.58
+mx2.gerwinski.de has IPv6 address 2a01:4f8:192:4405::170:58
+cassini/home/peter/bo/2024ws/dbs/20241120>

20241120/dns-02.txt

+cassini/home/peter/bo/2024ws/dbs/20241120> host mx2.gerwinski.de
+mx2.gerwinski.de has address 88.198.170.58
+mx2.gerwinski.de has IPv6 address 2a01:4f8:192:4405::170:58
+cassini/home/peter/bo/2024ws/dbs/20241120> 

20241120/ssh-01.txt

+cassini/home/peter/bo/2024ws/dbs/20241120> ssh main-0.cvh-server.de
+Linux main-0 6.1.0-22-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.94-1 (2024-06-21) x86_64
+
+The programs included with the Debian GNU/Linux system are free software;
+the exact distribution terms for each program are described in the
+individual files in /usr/share/doc/*/copyright.
+
+Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
+permitted by applicable law.
+Last login: Wed Nov 20 12:06:40 2024 from 195.37.15.82
+pgerwinski@main-0:~$
+logout
+Connection to main-0.cvh-server.de closed.
+cassini/home/peter/bo/2024ws/dbs/20241120> ssh -v main-0.cvh-server.de
+OpenSSH_9.2p1 Debian-2+deb12u3, OpenSSL 3.0.15 3 Sep 2024
+debug1: Reading configuration data /home/peter/.ssh/config
+debug1: /home/peter/.ssh/config line 28: Applying options for main-0.cvh-server.de
+debug1: Reading configuration data /etc/ssh/ssh_config
+debug1: /etc/ssh/ssh_config line 19: include /etc/ssh/ssh_config.d/*.conf matched no files
+debug1: /etc/ssh/ssh_config line 21: Applying options for *
+debug1: Connecting to main-0.cvh-server.de [88.99.194.201] port 22.
+debug1: Connection established.
+debug1: identity file /home/peter/.ssh/id_rsa type 0
+debug1: identity file /home/peter/.ssh/id_rsa-cert type -1
+debug1: identity file /home/peter/.ssh/id_ecdsa type -1
+debug1: identity file /home/peter/.ssh/id_ecdsa-cert type -1
+debug1: identity file /home/peter/.ssh/id_ecdsa_sk type -1
+debug1: identity file /home/peter/.ssh/id_ecdsa_sk-cert type -1
+debug1: identity file /home/peter/.ssh/id_ed25519 type -1
+debug1: identity file /home/peter/.ssh/id_ed25519-cert type -1
+debug1: identity file /home/peter/.ssh/id_ed25519_sk type -1
+debug1: identity file /home/peter/.ssh/id_ed25519_sk-cert type -1
+debug1: identity file /home/peter/.ssh/id_xmss type -1
+debug1: identity file /home/peter/.ssh/id_xmss-cert type -1
+debug1: identity file /home/peter/.ssh/id_dsa type 1
+debug1: identity file /home/peter/.ssh/id_dsa-cert type -1
+debug1: Local version string SSH-2.0-OpenSSH_9.2p1 Debian-2+deb12u3
+debug1: Remote protocol version 2.0, remote software version OpenSSH_9.2p1 Debian-2+deb12u3
+debug1: compat_banner: match: OpenSSH_9.2p1 Debian-2+deb12u3 pat OpenSSH* compat 0x04000000
+debug1: Authenticating to main-0.cvh-server.de:22 as 'pgerwinski'
+debug1: load_hostkeys: fopen /home/peter/.ssh/known_hosts2: No such file or directory
+debug1: load_hostkeys: fopen /etc/ssh/ssh_known_hosts: No such file or directory
+debug1: load_hostkeys: fopen /etc/ssh/ssh_known_hosts2: No such file or directory
+debug1: SSH2_MSG_KEXINIT sent
+debug1: SSH2_MSG_KEXINIT received
+debug1: kex: algorithm: sntrup761x25519-sha512@openssh.com
+debug1: kex: host key algorithm: ecdsa-sha2-nistp256
+debug1: kex: server->client cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: none
+debug1: kex: client->server cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: none
+debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
+debug1: SSH2_MSG_KEX_ECDH_REPLY received
+debug1: Server host key: ecdsa-sha2-nistp256 SHA256:kkDVI02KLySNK2cu0kHvDGXqakeIeJ3EWzF3cBL/WU8
+debug1: load_hostkeys: fopen /home/peter/.ssh/known_hosts2: No such file or directory
+debug1: load_hostkeys: fopen /etc/ssh/ssh_known_hosts: No such file or directory
+debug1: load_hostkeys: fopen /etc/ssh/ssh_known_hosts2: No such file or directory
+debug1: Host 'main-0.cvh-server.de' is known and matches the ECDSA host key.
+debug1: Found key in /home/peter/.ssh/known_hosts:30
+debug1: ssh_packet_send2_wrapped: resetting send seqnr 3
+debug1: rekey out after 134217728 blocks
+debug1: SSH2_MSG_NEWKEYS sent
+debug1: expecting SSH2_MSG_NEWKEYS
+debug1: ssh_packet_read_poll2: resetting read seqnr 3
+debug1: SSH2_MSG_NEWKEYS received
+debug1: rekey in after 134217728 blocks
+debug1: get_agent_identities: bound agent to hostkey
+debug1: get_agent_identities: agent returned 2 keys
+debug1: Skipping ssh-dss key /home/peter/.ssh/id_dsa - corresponding algo not in PubkeyAcceptedAlgorithms
+debug1: Will attempt key: /home/peter/.ssh/id_rsa RSA SHA256:pWPaC1MmdzZzGE6Sgi6LH9g9Bj4xiegwAMXdYfSXQFI agent
+debug1: Will attempt key: /home/peter/.ssh/id_ecdsa
+debug1: Will attempt key: /home/peter/.ssh/id_ecdsa_sk
+debug1: Will attempt key: /home/peter/.ssh/id_ed25519
+debug1: Will attempt key: /home/peter/.ssh/id_ed25519_sk
+debug1: Will attempt key: /home/peter/.ssh/id_xmss
+debug1: SSH2_MSG_EXT_INFO received
+debug1: kex_input_ext_info: server-sig-algs=<ssh-ed25519,sk-ssh-ed25519@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,sk-ecdsa-sha2-nistp256@openssh.com,webauthn-sk-ecdsa-sha2-nistp256@openssh.com,ssh-dss,ssh-rsa,rsa-sha2-256,rsa-sha2-512>
+debug1: kex_input_ext_info: publickey-hostbound@openssh.com=<0>
+debug1: SSH2_MSG_SERVICE_ACCEPT received
+debug1: Authentications that can continue: publickey
+debug1: Next authentication method: publickey
+debug1: Offering public key: /home/peter/.ssh/id_rsa RSA SHA256:pWPaC1MmdzZzGE6Sgi6LH9g9Bj4xiegwAMXdYfSXQFI agent
+debug1: Server accepts key: /home/peter/.ssh/id_rsa RSA SHA256:pWPaC1MmdzZzGE6Sgi6LH9g9Bj4xiegwAMXdYfSXQFI agent
+Authenticated to main-0.cvh-server.de ([88.99.194.201]:22) using "publickey".
+debug1: channel 0: new session [client-session] (inactive timeout: 0)
+debug1: Requesting no-more-sessions@openssh.com
+debug1: Entering interactive session.
+debug1: pledge: filesystem
+debug1: client_input_global_request: rtype hostkeys-00@openssh.com want_reply 0
+debug1: client_input_hostkeys: searching /home/peter/.ssh/known_hosts for main-0.cvh-server.de / (none)
+debug1: client_input_hostkeys: searching /home/peter/.ssh/known_hosts2 for main-0.cvh-server.de / (none)
+debug1: client_input_hostkeys: hostkeys file /home/peter/.ssh/known_hosts2 does not exist
+debug1: client_input_hostkeys: host key found matching a different name/address, skipping UserKnownHostsFile update
+debug1: Remote: /home/pgerwinski/.ssh/authorized_keys:5: key options: agent-forwarding port-forwarding pty user-rc x11-forwarding
+debug1: Remote: /home/pgerwinski/.ssh/authorized_keys:5: key options: agent-forwarding port-forwarding pty user-rc x11-forwarding
+debug1: Sending environment.
+debug1: channel 0: setting env LANG = "de_DE.UTF-8"
+debug1: pledge: fork
+Linux main-0 6.1.0-22-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.94-1 (2024-06-21) x86_64
+
+The programs included with the Debian GNU/Linux system are free software;
+the exact distribution terms for each program are described in the
+individual files in /usr/share/doc/*/copyright.
+
+Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
+permitted by applicable law.
+Last login: Wed Nov 20 12:08:49 2024 from 195.37.15.82
+pgerwinski@main-0:~$

20241120/ssh-02.txt

+cassini/home/peter/bo/2024ws/dbs/20241120> ssh 127.0.0.1
+The authenticity of host '127.0.0.1 (127.0.0.1)' can't be established.
+ED25519 key fingerprint is SHA256:GVxACWdsipZpAUCkggWoUssXdOiXyPWec5nMMqsxZ6M.
+This host key is known by the following other names/addresses:
+    ~/.ssh/known_hosts:484: [hashed name]
+Are you sure you want to continue connecting (yes/no/[fingerprint])? ^C
+cassini/home/peter/bo/2024ws/dbs/20241120> ssh-keygen -l -f /etc/ssh/ssh_host_ed25519_key.pub
+256 SHA256:GVxACWdsipZpAUCkggWoUssXdOiXyPWec5nMMqsxZ6M root@cassini (ED25519)
+cassini/home/peter/bo/2024ws/dbs/20241120> ssh 127.0.0.1                                     The authenticity of host '127.0.0.1 (127.0.0.1)' can't be established.
+ED25519 key fingerprint is SHA256:GVxACWdsipZpAUCkggWoUssXdOiXyPWec5nMMqsxZ6M.
+This host key is known by the following other names/addresses:
+    ~/.ssh/known_hosts:484: [hashed name]
+Are you sure you want to continue connecting (yes/no/[fingerprint])? SHA256:GVxACWdsipZpAUCkggWoUssXdOiXyPWec5nMMqsxZ6M
+Warning: Permanently added '127.0.0.1' (ED25519) to the list of known hosts.
+Linux cassini 6.1.0-26-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.112-1 (2024-09-30) x86_64
+
+The programs included with the Debian GNU/Linux system are free software;
+the exact distribution terms for each program are described in the
+individual files in /usr/share/doc/*/copyright.
+
+Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
+permitted by applicable law.
+You have mail.
+Last login: Wed Nov 20 12:21:44 2024 from ::1
+cassini/home/peter>

20241120/ssh-03.txt

+cassini/home/peter/bo/2024ws/dbs/20241120> sudo cat /etc/ssh/sshd_config.d/no-passwords.conf
+PasswordAuthentication no
+cassini/home/peter/bo/2024ws/dbs/20241120> sudo systemctl reload sshd
+cassini/home/peter/bo/2024ws/dbs/20241120>
+