1. 2/26/2003 Lecture 4 Computer System Administration Lecture 4 Networking Startup/DNS

2. 2/26/2003 Lecture 4 Networking Initialization: IRIX ● Hostname – /etc/sys_id ● IP Address – /etc/hosts ● nsswitch.conf ● Netmask – /etc/config/ifconfig-1.options ● Default route – /etc/config/static-route.options

3. 2/26/2003 Lecture 4 /etc/config/ifconfig-1.options ● Appended to ifconfig command for first interface – netmask 0xffffff00 ● 255.255.255.0 ● /24

4. 2/26/2003 Lecture 4 /etc/config/static-route.options ● Script file, multiple routing commands can be added – $ROUTE $QUIET add default 128.213.30.1

5. 2/26/2003 Lecture 4 IRIX: Multiple Interfaces ● Hostname-INTERFACE – /etc/hosts ● irix-1-ec0.sysadmin.cs.rpi.edu – /etc/config/ifconfig-#.options ● Netmasks, etc.. for additional controllers – /etc/config/static-route.options ● Add additional $ROUTE lines

6. 2/26/2003 Lecture 4 Solaris: Networking Startup ● Hostname – /etc/hostname.INTERFACE ● Machine hostname from primary interface ● IP Address – /etc/hosts ● /etc/nsswitch.conf ● Netmask – /etc/netmasks ● Default Route – /etc/defaultrouter

7. 2/26/2003 Lecture 4 Solaris: Multiple Interfaces ● Hostnames – /etc/hostname.INTERFACE ● Only primary interface sets global hostname ● IP Address – /etc/hosts ● Netmask – /etc/netmasks ● Static routes – Create your own startup script using route(1)

8. 2/26/2003 Lecture 4 FreeBSD: Networking Startup ● All in /etc/rc.conf ● Hostname – hostname=”hostname” ● IPAddress/Netmask – ifconfig_INTERFACE=”inet address netmask netmask” ● Default Route – defaultrouter=”address”

9. 2/26/2003 Lecture 4 FreeBSD: Multiple Interfaces ● All in /etc/rc.conf – No need to reset hostname ● IP addresses – Additional ifconfig_INTERFACE lines ● Static routes – static_routes=”name1 name2...” – route_name1=”route(8) args” ● route add ${route_name1}

10. 2/26/2003 Lecture 4 DNS: Client Configuration ● /etc/nsswitch.conf – IRIX/Solaris/FreeBSD5+/Many Linux Distributions – hosts: ● files – /etc/hosts ● dns – DNS ● nis – YP/NIS – Man(1)-page!

11. 2/26/2003 Lecture 4 DNS: Resolver ● /etc/resolv.conf – domain ● Default appended to end of most requests. – search ● List of possible extensions to requests – Mutually exclusive – nameserver ● Can be listed multiple times ● Adds additional servers to the ones queried

12. 2/26/2003 Lecture 4 Libresolv and state ● resolver library is stateless/unshared – Failed nameservers keep being tried, with delay ● Name Service Caching – Keeps state of servers – Solaris ● nscd – Name Service Cache Daemon – Irix ● nsd – Name Service Daemon

13. 2/26/2003 Lecture 4 DNS: 2 Databases ● Name to address (Forward) – Registrars ● Verisign, EDUCause, etc... – edu/com/net/org/biz/cc/... ● Address to name (reverse) – NICs ● ARIN/APNIC/RIPE – in-addr.arpa.

14. 2/26/2003 Lecture 4 DNS Hierarchies (forward)

15. 2/26/2003 Lecture 4 IP Delegations (reverse)

16. 2/26/2003 Lecture 4 Forward ● Forward – Delegated on “.” boundaries – Bottom up ● edu is the most broad ● then rpi is more specific ● then cs ● Etc.

17. 2/26/2003 Lecture 4 vs. Reverse ● Reverse – Delegated on “.” boundaries – Top down. ● 128.213 is the most broad (classes!) ● 30 is more specific ● 2 is a given host.

18. 2/26/2003 Lecture 4 IP Classes ● Class based IP routing – A ● 127 class A addresses, each address has 16.7million IPs – /8 – All addresses begin (bitwise) 0 – B ● ~50,000 class B addresses, each address has 65536 Ips – /16 – All Addresses begin (bitwise) 10 – C ● Many, 256 Ips, /24, begin “110”

19. 2/26/2003 Lecture 4 Classless Routing ● Poor utilization of IP addresses – Class A addresses largely wasted. ● Allows for almost arbitrary sized networks – 24.a.b.c no longer 1 network ● 24.5.7.x/24 ● 24.6.x.y/16 ● 24.8.0.0-24.9.255.255/17 ● 128.213.30.16-128.213.30.31/28 ● Much more load on routers

20. 2/26/2003 Lecture 4 DNS: Start of Authority ● SOA – Required to delegate a domain – Fields to specify maintainership of a domain ● Authoritative server ● Authoritative email (in DNS format) ● Serial number ● Refresh ● Retry ● Expire (TTL) ● Minimum

21. 2/26/2003 Lecture 4 DNS: Other records ● NS: NameServer – IN NS name ● A:Address – IN NS IP_Address ● MX:Mail Exchange – IN MX priority name ● TXT:Text – INTXT “data” ● RP: Responsible Person, points to a TXT

22. 2/26/2003 Lecture 4 DNS: Other Records ● CNAME (alias) – IN CNAME name – Cannot be combined with types other than A and PTR ● PTR (Pointer) (reverse DNS) – IN PTR name ● AAAA/A6 – 2 types of IPv6 address ● AAAA: raw, undelegated. A6: delegated

23. 2/26/2003 Lecture 4 Reverse Lookup ● Reverse (literally) lookup – IP Address must be reversed so it too is in bottom-up order. – Name-to-address: ● monica.cs.rpi.edu 128.213.7.2 – Address-to-name: ● 2.7.213.128.in-addr.arpa monica.cs.rpi.edu

24. 2/26/2003 Lecture 4 DNS: Forward Example @ INSOAturing.cs.rpi.edu. labstaff.cs.rpi.edu. ( 200302253;Serial 86400 ;Refresh 3600;Retry 604800;Expire (TTL) 86400 ) ;Minimum labstaffINTXT“Department of Computer Science” INNSturing.cs.rpi.edu. INNSstumble.cs.rpi.edu. INNSnetserv1.its.rpi.edu. turingINA128.213.1.1 INMX1mumble.cs.rpi.edu. stumbleINA128.213.8.7 INMX1mumble.cs.rpi.edu. netserv1.its.rpi.edu.INA128.113.1.5 wwwINCNAMEstumble

25. 2/26/2003 Lecture 4 DNS: Reverse Example @INSOAturing.cs.rpi.edu. labstaff.cs.rpi.edu. ( 200302213 86400 3600 604800 86400 ) INNSturing.cs.rpi.edu. INNSstumble.cs.rpi.edu. INNSnetserv1.its.rpi.edu. 2.7INPTRmonica.cs.rpi.edu. 1.1INPTRturing.cs.rpi.edu. 18.30INPTRirix-1.sysadmin.cs.rpi.edu.

26. 2/26/2003 Lecture 4 DNS: Forward Delegation delegateINNStheir.name.server. INNStheir- secondary.name.server. their.name.serverINAaddress their-secondary.name.serverINA address

27. 2/26/2003 Lecture 4 DNS: Reverse Delegation 24INNStheir.name.server. ;must be in fwd INNStheir-secondary.name.server. ;must be in fwd

28. 2/26/2003 Lecture 4 DNS: Classless Reverse Delegation ● Delegating reverse DNS when not on “.” boundaries – RFC 2317 – Clever and painfull use of CNAMEs(aliases) – Create new level of DNS in reverse and alias all reverse IPs to that.

29. 2/26/2003 Lecture 4 DNS: Classless Reverse Delegation, Delegator ; using delegation of 128.213.30.16/28 as an example 16/28INNSgroup-1-dns.sysadmin.cs.rpi.edu. INNSgroup-1-secondary- dns.sysadmin.cs.rpi.edu. 16INCNAME 16.16/28.30.213.128.in- addr.arpa. 17INCNAME 17.16/28.30.213.128.in- addr.arpa. 18INCNAME 18.16/28.30.213.128.in- addr.arpa. 19INCNAME 19.16/28.30.213.128.in- addr.arpa. 20INCNAME 20.16/28.30.213.128.in- addr.arpa. 21INCNAME 21.16/28.30.213.128.in- addr.arpa.

30. 2/26/2003 Lecture 4 DNS: Classless Reverse Delegation, Delegate-ed $ORIGIN 16/28.30.213.128.in-addr.arpa 16INPTRnet.group1.sysadmin.cs.rpi.edu. 17INPTRrouter.group1.sysadmin.cs.rpi.edu. 18INPTRirix.group1.sysadmin.cs.rpi.edu. 19INPTRsolaris.group1.sysadmin.cs.rpi.edu. 20INPTRfreebsd.group1.sysadmin.cs.rpi.edu.

31. 2/26/2003 Lecture 4 DNS: Server Configuration ● Type of server – Master – Slave – Cache ● Zone Config files – Forward – Reverse – hints

32. 2/26/2003 Lecture 4 named.conf acl transferers { 128.213.0.0/16; 128.113.0.0/16; 1.2.3.4; }; acl local {128.213.0.0/16; 128.113.0.0/16}; acl evil {2.3.4.5;}; options { directory “/etc/namedb”; allow-transfer { transferers; }; allow-recursion { local; }; blackhole { evil; }; recursion no; }; zone “vassar.edu” { type slave; file “slave/vassar.edu”; masters { 143.229.1.6; }; };

33. 2/26/2003 Lecture 4 Named.conf (cont) Zone “.” { /* sets the default $ORIGIN */ type hint; file “named.root”; /*file of root “.” name servers. }; zone “213.128.in-addr.arpa” { type master; file “master/cs.rpi.edu.rev”; also-notify { 128.213.8.7; 128.113.1.3; } }; zone “cs.rpi.edu” { type master; file “master/cs.rpi.edu”; also-notify { 128.213.8.7; 128.113.1.3; } };

34. 2/26/2003 Lecture 4 named/bind operations ● $ORIGIN – Changes suffix appended to all unqualified names ● $GENERATE – Used to make series of hosts – Forward ● $GENERATE 100-200 d11-$.dyn IN A 128.213.11.$ – Reverse ● $GENERATE 100-200 $.11 IN PTR d11- $.cs.rpi.edu.

35. 2/26/2003 Lecture 4 Name-Server Packages ● Solaris – bind8 ● SUNWcsu – Core System Utilities – Already installed – Bind9 ● http://www.sunfreeware.com/programlistsparc9.html#bind 9 ● SGI/Irix – Bind8 included – Bind9 ● http://www.sunfreeware.com/programlistsparc9.html#bind 9

36. 2/26/2003 Lecture 4 Name Server Packages(cont) ● FreeBSD – Bind8: Included – Bind9 ● pkg_add -r bind9 ● Remember to make sure it starts automatically!

37. 2/26/2003 Lecture 4 Group Names ● foo.group-name.sysadmin.cs.rpi.edu ● Existing names will be going away

38. 2/26/2003 Lecture 4 Next Lecutre ● NIS!