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59 Cards in this Set
- Front
- Back
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PLIP
PPP HIPPI |
PLIP - Parallel Line Interface Protocol
PPP - point to point protocol HIPPI - High-Performance Parallel Interface |
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protocol stack def
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protocol stack is a set of software that converts and encapsulates data between layers of abstraction.
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IP def
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IP - internet protocol
The core on TCP/IP Provides best effort delivery IP handles addresses |
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ICMP def
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ICMP - internet control message protocol
used for sending messages between computers relies upon IP |
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UDP def
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UDP - user datagram protocol
layer 3 UDP faster than TCP DNS and NFS are build upon IDP |
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TCP def
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TCP - transport control protocol
TCP creates full connection with error checking and correction as well as other feature Small performance penelty |
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MAC address
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Media Access Control address
16 bytes in length |
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What is specific for network devices in linux
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they dont have entries in /dev
instead low-level network utilities take the device names and down and work with then directly |
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NDP abr
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NDP - neighbor Discovery Protocol
ARP for IPv6 |
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CIDR
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CIDR Classless Inter-Domain Routing
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IPv6 site local address begin with hex ? (4)
and usage |
IPv6 site-local addresses may be routed within a site but not off-site.
fec fed fee fef |
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Link-local addresses def/list
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restricted to a single network segment, they should not be routed at all
begin with fe8 fe9 fea feb |
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nslookup cmd
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performs DNS lookup and returns result
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host cmd
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replacement for the simpler use nslookup - lacks interactive mode
host target.name |
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dig cmd
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perfors a more complex DNS lookup
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whois cmd
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information on a domain
whois sybex.com -H omits legal disclimer |
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file that contain mappings of IP addresses to hostnames
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/ect/hosts
127.0.0.1 localhost 192.168.7.23 apollo.luna.edu apollo |
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Linux normally performs lookups in /etc/hosts before it uses DNS, you can modify this behavior by editing the _____________ file
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/etc/nsswitch.conf
line lists the order of the files and dns options, which stand for /etc/hosts and DNS, respectively: hosts: files dns |
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What is the name of the file that works much like /etc/hosts but applies to network addresses
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/etc/networks
loopback 127.0.0.0 mynet 192.168.7.0 This example sets up two linkages: the loopback name to the 127.0.0.0/8 network and mynet for the 192.168.7.0/24 network. It’s seldom necessary to edit this file. |
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port and protocol
DCHP Portmapper auth/ident NNTP |
DCHP - 67 -- UDP
Portmapper - 111 -- TCP/UDP auth/ident - 113 -- TCP NNTP - 119 -- TCP |
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port and protocol
NetBIOS Session IMAP SNMP XDMCP X Window System |
NetBIOS Session - 139 -- TCP
IMAP - 143 -- TCP SNMP - 161 -- UDP XDMCP - 177 - UDP X Window System - 6000/6007 - TCP |
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port and protocol
LDAP MS Dir.Service SMTP over SSL IPP IMAP over SSL |
LDAP - 389 -- TCP
MS Dir.Service - 445 -- TCP SMTP over SSL - 465 -- TCP IPP - 631 -- TCP IMAP over SSL - 993 - TCP |
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Where you configure the system to link the servers to the correct port
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/etc/services
ssh 22/tcp # SSH Remote Login Protocol ssh 22/udp # SSH Remote Login Protocol telnet 23/tcp smtp 25/tcp |
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If your network hardware isn’t correctly detected to correct the problem, you must load your network hardware driver with the _____ cmd
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modprobe tulip
You must know the name of your network hardware’s kernel module (tulip in this example). |
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Three DHCP clients are in common use on Linux (list)
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pump
dhclient dhcpcd |
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Ideally the DHCP client runs at system boot-up this is usual handled by either ________ or by __________
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by its own SysV start-up file or by
part of the main network configuration start-up file called network or networking |
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The system often uses a line in a config file to determine whether to run a DHCP
in Red Hat/Fedora __________ in Ubuntu |
in Red Hat/Fedora
/etc/sysconfig/network-scripts/ifcfg-eth0 with line like BOOTPROTO=dhcp in Ubuntu /etc/network/interfaces iface eth0 inet dhcp |
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If you need to manually run a DHCP client type its name as root followed by a network identifier as in _________
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dhclient eth0
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long term config files for network configuration (2)
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/etc/sysconfig/network-scripts/ifcfg-eth0
/etc/network/interfaces |
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typical ifcfg-eth0
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DEVICE=eth0
BOOTPROTO=static IPADDR=192.168.29.39 NETMASK=255.255.255.0 NETWORK=192.168.29.0 BROADCAST=192.168.29.255 GATEWAY=192.168.29.1 ONBOOT=yes |
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You can manually set the gateway via the
To set it permanently you need to adjust a config file |
route cmd
/etc/sysconfig/network.routes |
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In order for Linux to use DNS to translate between IP addresses adn host-name you must specify at least one DNS server in the __________ config file
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/etc/resolv.conf
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in Ubuntu, you would edit __________________ for the network configuration
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/etc/network/interfaces
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program to display current ip config
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ifconfig
+ you can set them with the same command ifconfig eth0 up 192.168.29.39 netmask 255.255.255.0 |
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set up a route for traffic beyond your current network cmd
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# route add default gw 192.168.29.1
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view interface configuration cmd (for interface eth0)
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ifconfig eth0
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route cmd output
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#route
Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 192.168.29.0 * 255.255.255.0 U 0 0 0 eth0 127.0.0.0 * 255.0.0.0 U 0 0 0 lo default 192.168.29.1 0.0.0.0 UG 0 0 0 eth0 last line shows the default route, which describes what to do with everything that doesn’t match any other entry in the routing table11 |
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simplifi ed version of the route syntax is as follows:
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route {add | del} [-net | -host] target [netmask nm] [gw gw]. [reject] [[dev] interface]
-net and -host options force route to interpret the target as a network or computer address, respectively reject keyword installs a blocking route, which refuses all traffic destined for the specified network |
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example, consider a network in which packets destined for the 172.20.0.0/16 subnet should be passed through the 172.21.1.1 router, which isn’t the default gateway system. You can set up this route with the following command:
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# route add -net 172.20.0.0 netmask 255.255.0.0 gw 172.21.1.1
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If Linux is to act as a router it must accept packets and send them on to the destination network. To enable his feature you must modify
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/proc/sys/net/ipv4/ip_forward
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Permanently setting ip forwarding requires modifying ________________ config file
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/etc/sysctl.conf
with net.ipv4.ip_forward = 1 |
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after this cmd eth0 will be fully configured, including all routing info assuming you've properly configure it by DHCP or editing /etc/netowrk/interface and /etc/sysconfig/network-scripts/ifcfg-eth0
Bring the interface down |
ifup eth0
ifdown eth0 |
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tool for setting your hostname locally
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hostname nessus.expample.com
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domain name cd
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set the domain nae as used by NIS
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dnsdomainname cmd
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sets the domain name as used by DNS
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Fedora looks at _____________ for hostname config to be used at boot
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/etc/sysconfig/network
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Most Linux distros use _______________ and __________________ for hostname config to be used at boot
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/etc/hostname or /etc/HOSTNAME
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Cmd to display your computer’s routing table information
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route -n
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Bring down the local Ethernet connection by typing
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ifconfig eth0 down
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in linux ping continues sending packets once every second until its interrupted by what cmd key combination
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Ctrl + C
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How can you specify ping limit
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-c
ping -c 4 speaker |
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$ traceroute -n 10.1.0.43
traceroute to 10.1.0.43 (10.1.0.43), 30 hops max, 52 byte packets what -n does |
The -n option to this command tells it to display target computers’ IP addresses rather
than their hostnames. |
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tracepath program expl
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an alternative to traceroute. In basic operation, it’s similar, although it produces one line of output for each test packet and so yields longer outputs than traceroute.
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netstat options
--interface / -i --route / -r |
--interface / -i
obtains info about network interfaces like ifconfig --route / -r obtains routing table info |
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netstat options
--masquerade / -M --program / -p |
--masquarade / -M
obtain info about connections mediate by the Linux's NAT feature --program / -p attempts to provide info about the programs that are using network connections |
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netstat options
without any options --all / -a |
netstat without any options returns information about open ports and the system to which they connect
--all / -a causes netstat to display info about the ports that server programs open to listen for network connection usually used with the other options |
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tcpdump program expl
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this utility is a packet sniffer, intercepts network packets and log them or display them on the scree
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output of # tcpdump
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tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 96 bytes 19:31:55.503759 IP speaker.example.com.631 > 192.168.1.255.631: UDP,. length: 139 19:31:55.505400 IP nessus.example.com.33513 > speaker.example.com.domain:. 46276+ PTR? 255.1.168.192.in-addr.arpa. (44) 19:31:55.506086 IP speaker.example.com.domain > nessus.example.com.33513:. 46276 NXDomain* 0/1/0 (110) |
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tcpdump options
-A -D -n -v -w |
-A - displays packet content in ASCII
-D - list of interfaces tcpdump can listen -n - displays all addresses numerically -v - additional packet info -w file - writes the captured packets to a file |
