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Linux and network security

Feb 25, 2016




A short two-part talk introducing: Basic Linux/Unix system administration ( CentOS /RHEL5) General Computer/Network security … for the G53SEC module. Nick Reynolds. Linux and network security. CentOS 5. Adding Accounts. Need entry in /etc/ passwd Need password in /etc/shadow - PowerPoint PPT Presentation

Setting Up TCP/IP Services

Linux and network securityA short two-part talk introducing:

Basic Linux/Unix system administration (CentOS/RHEL5)General Computer/Network security

for the G53SEC module.

Nick Reynolds.CentOS 5Adding AccountsNeed entry in /etc/passwdNeed password in /etc/shadowNeed home directory /home/[username]Correct Permissions

$ man adduser$ adduser

$ man passwd$ passwd Gui Alternative:redhat-config-usersThe Telnet Server (telnetd)Runs on receiving a connection man xintedStart with: chkconfig krb5-telnet onStop with:chkconfig krb5-telnet off

Configuring the Telnet ServerRead manual page:man telnetdSet up accounts using:adduserChange account shell:chsh

(Tip: man ssh, chkconfig sshd on/off)Other Servicesftp serverhttpd server (apache)ssh serverNetwork Configuration (Optional)redhat-config-network-gui

6Pages, DocumentRoot in config. Cgi-bin ScriptAlias /var/www/cgi-binSoftware Installs DistributionSearching:yum search [string]Installing:yum install [package]Staying up to date:yum updateLots more!:man yum man yum.conf

Monitoring The SystemCheck logs:/var/log/*Monitor network activity:tcpdumpMonitor processes:pstopUseful CommandsMove between accounts:/bin/su [username]Permissions and ownership:chmod chgrp chown Manual pages:man Useful ResourcesCentOS5 (RedHat EE) Documentation Documentation Project Engines!Final CentOS NotesMany ways to achieve the same result.Experiment within a user account.Dont make to many changes in one go.Stay up to date (yum update)Advanced methods to configure servers:man pam

General Network/Computer SecurityEncryptionAccess PermissionsWho/what do you trust?Network InfrastructureEncryptionEncryptionUse secure Protocols


telnetsshftpscpimapimapshttphttpsAccess PermissionsAccess PermissionsFile/directory permissions

FirewallsWho/What do you trust?Who/What do you trust?DHCP?

IP Addresses?Network InfrastructureNetwork InfrastructureWhere does your data go?

Switches? Hubs? Which route?

Wi-fiThe End!

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