95 lines
1.9 KiB
Markdown
95 lines
1.9 KiB
Markdown
---
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description: >-
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this week we configured dhcp01-nathan to run the dhcp server. now wks01 uses
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dhcp rather than static IP assignment
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---
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# Lab04 - DHCP
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## DHCP configuration
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* connect to dhcp01-nathan via puTTY
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* `sudo yum install dhcp`
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* configure `/etc/dhcp/dhcpd.conf` file
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* start\&enable dhcp
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* configure dhcp on firewall
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* configure wks01-nathan to use DHCP instead of static IP
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#### to start dhcp
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`systemctl start dhcpd`
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#### to check status of dhcp
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`systemctl status dhcpd`
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#### configure dhcp to start on boot
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`systemctl enable dhcpd`
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#### configure dhcp on firewall
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* `firewall-cmd --add-service=dhcp --permanent`
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* `firewall-cmd --reload`
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* `firewall-cmd --list-all`
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#### search for dhcp logs from wks01-nathan
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`sudo cat /var/log/messages | grep wks01-nathan`
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#### release dhcp
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`ipconfig /release`
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#### renew dhcp
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`ipconfig /renew`
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#### filtering dhcp messages in wireshark
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`udp.port==67`
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## Disable root access via ssh
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* `nano /etc/ssh/sshd_config`
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* change `PermitRootLogin` from yes to no and uncomment
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* `systemctl restart sshd`
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## File Permissions
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#### how to create a group
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`groupadd [groupname]`
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#### how to add a user to a group
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`usermod -aG [groupname] [username]`
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#### how to change the owner of a file
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`chown filename [username]`
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#### how to change the group of file
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`chgrp filename [groupname]`
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## Changing file permissions
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#### Method 1: using bit values
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* Read: 4
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* Write: 2
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* Execute: 1 Add up the numbers to set permissions for each accessor (owner/group/everyone else)
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example: `chmod 640 file.txt` give read/write to owners, read to group members, and no access to everyone else
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#### Method 2: adding/removing file permissions individually
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* `chmod u+/-(r/w/x) [filename]` - users (owner)
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* `chmod g+/-(r/w/x) [filename]` - group
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* `chmod o+/-(r/w/x) [filename]` - others (everyone else)
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example: `chmod g+w file.txt` gives write permissions to the group of `file.txt`
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