1. Linux Networking #2 Dr. Michael L. Collard www.sdml.info/collard www.sdml.info/collard/linux collard@cs.kent.edu 1

2. Network Configuration /etc/network/interfaces Used by ifup, ifdown NetworkManager replaces this # The loopback interface auto lo iface lo inet loopback # The first network card auto eth0 iface eth0 inet static address 131.123.42.38 netmask 255.255.255.224 broadcast 131.123.42.63 gateway 131.123.42.33 # dhcp iface eth1 inet dhcp

3. Routing Typically use a dedicated router as a gateway Computer as a gateway: – routed daemon – Uses RIP (Routing Information Protocol) – GNU Zebra – Uses RIP, OSPF (Open Shortest Path First), and BGP (Border Gateway Protocol)

4. Name Service Translates names to IP addresses DNS (Domain Name System) BIND (Berkerly Internet Name Domain) name server – de facto standard open source name server – named BIND server Clients: – dig – host

5. NFS (Network File System) Distributed file system Server – nfsd – exportfs, /etc/export – exported directories – /etc/hosts.allow, /etc/hosts.deny – nfsd Client – mounts exported directory mount servername:/projects /mnt/nfs/projects – Typically automounted

6. NIS (Network Information System) Client-server directory service protocol for distributing system configuration data (user and host names) Originally called: Yellow Pages (YP) ypserv – server daemon ypbind – client program Integrated into system password operations

7. NIS+ Sun replacement for NIS, implementation different from NIS – hierarchical – based Secure RPC (servers must authenticate clients and vice-versa) – may be replicated read-only – finer-grained permissions on data and operations Sun recommends to switch to LDAP (Lightweight Directory Access Protocol)

8. Firewalls Secure computer between an internal network and an external network Set of rules – chains netfilter – hooks in Linux kernel for filtering packets iptables – set up, maintain, and list IP packet filter rules