Linux Networking #2 Dr. Michael L. Collard 1

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 netmask broadcast gateway # dhcp iface eth1 inet dhcp

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)

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

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

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

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)

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