Search results “Ip options flags”
Wireshark 101: Transmission Control Protocol, HakTip 126
This week on HakTip, Shannon Morse explains the Transmission Control Protocol (or TCP) within Wireshark. Today we are breaking down the Transmission Control Protocol or TCP for short, which runs in Layer 4 of the OSI model and runs on top of IP. TCP basically makes sure your data gets to where it's supposed to go in a reliable way. Consider that IP is the pizza, and TCP is the pizza delivery guy (or girl), she ensures your pizza gets to you on time. Let's check out a TCP Header Packet. The first part will be the Source Port, used to transmit the packet, then you have the Destination Port which is the port to where the packet will be transmitted. Next up is the Sequence Number. This ensures that part of the data stream isn't missing from the whole packet. It identifies the TCP segment. The Acknowledgment Number is the sequence # for the next packet. Flags can include URG, ACH, PSH, RST, SYN, and FIN for type of TCP packet. Window Size is the size of the TCP receiver buffer in bytes. Checksum ensures the contacts are intact and legit. Urgent Pointer is if the URG flag is there, this part will give extra instructions about where the CPU should begin reading data in the packet. And options are extra info. Let's take a look at a TCP Packet header so we can point these out. TCP works by transmitting data on ports, which range between 1-65,535. Ports 1-1023 are Standard Ports (like Port 80 for HTTP falls within this category), and ports 1024-65535 are ephemeral ports, which are randomly selected when a device needs to find an open port. Both the destination and the client need to know what port the other is listening on to be able to transmit data between them. Oftentimes, a source port will be chosen at random when TCP sends a packet. TCP packets start with a handshake that ensures the host and destination are up and ready to communicate, checks the open port, and sends a sequence number so data stays in line. The host will send a SYN packet to the destination, the destination will send a SYN/ACK packet, then the Host will send an ACK packet back. During this handshake, the Sequence Number will go up by one each time. The TCP Teardown is the last thing that happens between the two devices before their communication is over, and it's signified by a FIN flag. The host sends the destination a FIN/ACK packet, then the destination sends the host an ACK packet, then a FIN/ACK, and the host responds with an ACK. Let's see if we can find a teardown packet header. Lastly, sometimes a TCP packet will need to send something called a RESET, or RST as it would be called in the Flag section. If a connection is halted all of a sudden by accident, the TCP packet will try to reset with this flag. This will halt all traffic during the sequence and close out the packet. Let me know what you think. Send me a comment below or email us at [email protected] And be sure to check out our sister show, Hak5 for more great stuff just like this. I'll be there, reminding you to trust your technolust. -~-~~-~~~-~~-~- Please watch: "Bash Bunny Primer - Hak5 2225" https://www.youtube.com/watch?v=8j6hrjSrJaM -~-~~-~~~-~~-~-
Views: 36236 Hak5
Total Length, ID, Flags, and Fragment Offset
Cisco CCIE Security Addressing and Protocols Tutorial (Complete Course Lecture No.20) TCP, UDP, and IP Protocols Length, ID, Flags, and Fragment Offset
IP Header: Networking & TCP/IP Tutorial. TCP/IP Explained
IP Header: Networking & TCP/IP Tutorial. TCP/IP Explained TRANSCRIPT: Today we examine the IP Header in great detail. So 1st lets look at the location of IP in the TCP/IP Stack. We notice that its in the Network Layer, which is layer 3. Now let’s examine the fields in detail. Version (4 Bits) Defines the version of the IP Protocol. Currently version you have mostly vers 4, ie IPv4 with Ipv6 coming in. Vers 6 could totally replace 4, probably around the same time porn is totally eliminated from the internet. Header Length (4 bits) This is the total length of the header in 4 byte words (that’s 32 bits for you n00bs). Meaning it points to the beginning of the data.With no options the header length is 20 bytes, so the value of the field is 5 (20 / 4). Add options and guess what: value increases. Service Type (8 bits) This was originally TOS, to indicate the QOS (Quality of Service) desired in networks that offer service precedence. So high precedence traffic got the royal treatment. Just for fun they changed it to Differentiated Services, still concerned precedence, but with a different interpretation. But it’s still compatiblewith the original TOS. Total Length (16 bit) This is the total length of the IP datagram, in bytes including header and the data. Do the math: 16 bits allows for a total length of up to 65,535. Try sending a 65,000 byte datagram over your production network just for fun Identification (16 bits) If the datagram is fragmented, all the fragments will have same unique identification value. This way the receiving end knows that all fragments with same identification value need to be assembled back into one datagram Flags (3 bit) Bit 0: Reserved (for what, nobody knows) Bit 1: Do not Fragment. If set to 1, may not be fragmented. So if MTU is too small, datagram is dropped. Remember MTU = Maximum Transfer Unit Bit 2: More fragments. If set to 1, then the datagram is not the last fragment OK, we just came across 2 important terms, Fragmentation & MTU. Let’s discuss them now before proceeding What’s Fragmentation? LANs & WANs have a limit on the amount of data that can be carried in a frame (at layer 2), which is usually Ethernet. That limit is called the MTU = Maximum Transfer Unit. But the datagram prepared at the network layer, may be larger the MTU, due to the large amount of that needs to be sent. In this case, the datagram needs to be fragmented to smaller unit before being passed to the data link layer. Fragmentation offset (13 bits) Indicates the relative position of each particular frag when a datagram is fragmented. It’s the offset of the original datagram in 8 byte units. Note carefully - 8 byte units. Example - Datagram of 3200 bytes is split into3 frags1st Frag: Carries the 1st 1400 bytes. Being the 1st frag it’s offset is always 0.2nd Frag: Carries the next 1400 bytes. It’s offset is 175. Why? It’s the bytes in theprior frag, divided by 8.Last Frag: Carries the next 800 bytes. It’soffset is 350. Why? It’s the bytes in the prior 2 frags (2800) divided by 8 Time to live (8 Bits) Prevents the datagram from hanging around endlessly, like unwanted guests, should routing tables get screwy. Each router it hits decrements the TTL by 1, & when TTL gets to 0, the datagram is unceremoniously discarded. Use of TTL is what makes Traceroute work Protocol (8 bits) Defines the upper layer Protocol. A value of 6 indicates TCP sits on top of the IP datagram. Value of 17 indicates UDP. 1 indicates ICMP. There’s over a 100 more, some important, most obscure. Header checksum (16 bits) Purpose of checksum is to detect corruption in transit. For IP, the checksum covers the header but not the data. The sender uses analgorithm (one’s complement arithmetic, if you must know) on the header & the result is sent with the packet. Then the receiver uses same algorithm over the header, and comes up with it’s own result result. If the results don’t match the packet is rejected like a geek at senior prom. Source IP Address (32 bits) I thought long & hard about how to describe this one. In a stroke of genius I came upwith “the IP address of the source” It looks like this: Not this: 68-A3-C4-3F-52-53 Destination IP Address (32 bits) This one should be pretty muchself explantory after reading my brilliant explanation on Source IP address Options + Padding (32 bits) Options don’t seem to be used too much solet’s blow it off for now. If your do use em,you add enough padding so that the field is exactly 32 bits.Seems like fertile ground for crafted packethacks This has been Huckleberry. Please mash down that LIKE button right now before you forget.
Views: 13377 Packethacks.com
TCP: Transmission control protocol | TCP Header | Transport layer | part -1
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Views: 47200 Gate Smashers
TCP/IP Training  IPv4 Header
An overview of the fields in the IPv4 header. Using Wireshark to examine TCP/IP SIP packets.
Views: 22939 TrainingCity
IP header format and explanation in hindi By Prince Tiwari
Like Subscribe and share video. For Notes Visit My Blog : https://cciegamer.blogspot.com/ Version(4 bits) : This is the first field in the protocol header. This field occupies 4 bits. This signifies the current IP protocol version being used. Most common version of IP protocol being used is version 4 while version 6 is out in market and fast gaining popularity. Header Length(4 bits) : This field provides the length of the IP header. The length of the header is represented in 32 bit words. This length also includes IP options (if any). Since this field is of 4 bits so the maximum header length allowed is 60 bytes. Usually when no options are present then the value of this field is 5. Here 5 means five 32 bit words ie 5 *4 = 20 bytes. Type of service(8 bits) : The first three bits of this field are known as precedence bits and are ignored as of today. The next 4 bits represent type of service and the last bit is left unused. The 4 bits that represent TOS are : minimize delay, maximize throughput, maximize reliability and minimize monetary cost. Total length(16 bits): This represents the total IP datagram length in bytes. Since the header length (described above) gives the length of header and this field gives total length so the length of data and its starting point can easily be calculated using these two fields. Since this is a 16 bit field and it represents length of IP datagram so the maximum size of IP datagram can be 65535 bytes. When IP fragmentation takes place over the network then value of this field also changes. There are cases when IP datagrams are very small in length but some data links like ethernet pad these small frames to be of a minimum length ie 46 bytes. So to know the exact length of IP header in case of ethernet padding this field comes in handy. Identification(16 bits): This field is used for uniquely identifying the IP datagrams. This value is incremented every­time an IP datagram is sent from source to the destination. This field comes in handy while reassembly of fragmented IP data grams. Flags(3 bits): This field comprises of three bits. While the first bit is kept reserved as of now, the next two bits have their own importance. The second bit represents the ‘Don’t Fragment’ bit. When this bit is set then IP datagram is never fragmented, rather its thrown away if a requirement for fragment arises. The third bit represents the ‘More Fragment’ bit. If this bit is set then it represents a fragmented IP datagram that has more fragments after it. In case of last fragment of an IP datagram this bit is not set signifying that this is the last fragment of a particular IP datagram. Fragment offset(13 bits): In case of fragmented IP data grams, this field contains the offset( in terms of 8 bytes units) from the start of IP datagram. So again, this field is used in reassembly of fragmented IP datagrams. Time to live(8 bits) : This value represents number of hops that the IP datagram will go through before being discarded. The value of this field in the beginning is set to be around 32 or 64 (lets say) but at every hop over the network this field is decremented by one. When this field becomes zero, the data gram is discarded. So, we see that this field literally means the effective lifetime for a datagram on network. Protocol(8 bits) : This field represents the transport layer protocol that handed over data to IP layer. This field comes in handy when the data is demultiplex­ed at the destination as in that case IP would need to know which protocol to hand over the data to.12/18/2016 IP Protocol Header Fundamentals Explained with Diagrams Header Checksum(16 bits) : This fields represents a value that is calculated using an algorithm covering all the fields in header (assuming this very field to be zero). This value is calculated and stored in header when IP data gram is sent from source to destination and at the destination side this checksum is again calculated and verified against the checksum present in header. If the value is same then the datagram was not corrupted else its assumed that data gram was received corrupted. So this field is used to check the integrity of an IP datagram. Source and destination IP(32 bits each) : These fields store the source and destination address respectively. Since size of these fields is 32 bits each so an IP address os maximum length of 32 bits can be used. So we see that this limits the number of IP addresses that can be used. To counter this problem, IP V6 has been introduced which increases this capacity
Views: 9560 CCIE Gamer
03 05 TCP Flags
Views: 4869 bisdakTECH
TCP Header: Networking & TCP/IP Tutorial. TCP/IP Explained
TCP Header: Networking & TCP/IP Tutorial. TCP/IP Explained Today we examine the TCP header in great detail let’s look at the location of TCP in the TCP/IP stack resides in the transport layer which is layer 4 note the transport layer contains UDP and TCP you going to either use TCP or UDP but not both. TCP is much more complex because it’s connection oriented Let’s examine the fields in detail source port destination port sequence number acknowledgment number HLEN Reserved URG ACK PSH RST SYN FIN window size checksum urgent pointer options+ padding
Views: 34135 Packethacks.com
How TCP Works -  No Operation Option
In this video we will take a look at the No Operation option in the TCP Handshake. This field acts as a filler to pad out the header size to a multiple of 4 bytes. Let's see why that is important. Subscribe for more tips and tricks using Wireshark! Got network problems or want some training? Let's get in touch www.packetpioneer.com/contact
Views: 2748 Chris Greer
Analyzing DNS with Wireshark
tons of info at www.thetechfirm.com When you get to the task of digging into packets to determine why something is slow, learning how to use your tool is critical. I’ve been using and training analysts how to use Wireshark for over 10 years, and enjoy sharing tips and tricks to make your life easier. As a protocol analyst, you should be aware of which protocols your application use. When I state that point many people think of the usual protocols, like IPv4, IPv6, TCP, TCP, HTTP, etc. Not only should you be aware of which protocols your application uses but you should also consider other additional protocols that your application depends on for proper operation. .. Read the rest at networkcomputing.com
Views: 27860 The Technology Firm
Introduction to TCPDUMP
Twitter: @davidmahler LinkedIn: https://www.linkedin.com/in/davidmahler Links: reference: www.tcpdump.org reference: tcpdump man page! tcpdump options used in this video: Version check: -h List interfaces: -D Capture on eth0: -i eth0 Stop at 500 (or any #) of packets: -c500 No name resolution: -n Change capture size (ex 96 Bytes): -s96 Max capture size: -s0 save to file capture.pcap: -w capture.pcap -v Read from a capture file: -r capture.pcap Filters: IP: host (ip addr) Source IP: src host (ip addr) Dest. IP: dst host (ip addr) port: port 80 MAC address: ether host (mac address) protocol filters: tcp, udp, icmp, arp, rarp, ip6, (others) SYN flag: "tcp[tcpflags] & tcp-syn != 0" RST flag: "tcp[tcpflags] & tcp-rst != 0" Output options: View MAC info: -e Include hex and ASCII: -XX ASCII only: -A max verbosity: -vvv ignore checksum errors: -K quiet: -q timestamp options: -t, -tt, -ttt, etc...
Views: 65864 David Mahler
CCIE R&S: Understanding Transmission Control Protocol (TCP) : TCP Push Function
CCIE R&S: Understanding Transmission Control Protocol (TCP) : TCP Push Function At first glance, the Transmission Control Protocol might seem fairly easy. Data gets transmitted, and then an acknowledgment is returned. But as one takes the time to research this protocol, it quickly becomes quite more complex than previously assumed. This course will go deep into the functioning of TCP at a level that you will be hard-pressed to find anywhere else. You will not only learn details about how TCP develops it system of sequencing segments and providing acknowledgments, but you’ll also learn the nitty-gritty details of things like the Sliding Window, the MSS, the Receive Window, and the TCP “Urgent” and “Push” functions. You’ll learn the differences between TCP “Passive” and “Active” Opens, and how these affect the creation of TCBs. You’ll learn about Nagle’s Algorithm, the “TCP_NoDelay” option, and how both of these affect how-and-when TCP segments are created. In addition, this course also goes into details about TCP’s congestion avoidance mechanisms of Slow Start, the Congestion Avoidance Algorithm, Fast Retransmit, and TCP Fast Recovery, and much, much more. If you would like to view the entire course, visit www.ine.com to sign up for an All Access Pass! https://streaming.ine.com/c/ccie-rs-understaning-tcp
Views: 11125 INEtraining
Top 10 Wireshark Filters
The syntax for setting display filters in Wireshark can be difficult to remember. In this video, we cover the top 10 Wireshark display filters in analyzing network and application problems. In short, the filters are here: ip.addr == tcp or dns tcp.port == 443 tcp.analysis.flags !(arp or icmp or dns) follow tcp stream tcp contains facebook http.response.code == 200 http.request tcp.flags.syn == 1 If there is one missing from the list that you like to use, please comment below. www.packetpioneer.com
Views: 280655 Chris Greer
Building a Better Redstone Computer Tutorial 9: Tweaks & Flags
Previous Part: https://youtu.be/DlTZuUaM-x4 In this video, we make a few small improvements, fix a few small problems, and start working on the flags system. This and my other videos are done on the Open Redstone Engineering or ORE server. Anyone is welcome to come on: There's a lot of awesome redstone builds, and a lot of brilliant redstone engineers who'd love to talk redstone with you. There's even a school of redstone where you can learn redstone from the best. Open Redstone Engineer's server: ip: mc.openredstone.org Website: http://openredstone.org/ Youtube: https://www.youtube.com/user/OpenRedstone
Views: 1487 bennyscube
Wireshark 101: The Dynamic Host Configuration Protocol, HakTip 128
Today on HakTip, Shannon explains DHCP and how it relates to Wireshark. DCHP stands for Dynamic Host Configuration Protocol, and it's a common upper-layer protocol. DHCP makes it super easy for devices to get an IP address automatically. DHCP's goal is to assign address to clients during this thing called a 'renewal process'. In Wireshark, first we have OpCode - to show you if it's a reply or a request. Then Hardware type (like if it's Ethernet), the hardware length of the hardware address, Hops (which are used by relay agents to assist in finding a DHCP server), a Transaction ID to pair requests and responses, Seconds Elapsed (which shows you how long it's been since the client first requested the address from a DHCP server), then we have Flags (which shows what kind of traffic this DHCP client can accept), Client IP address (you!), Your IP address (which becomes the Client), the Server IP address, Gateway IP address, Client hardware address (MAC), the Server Host Name, Boot File, and Options. The Renewal Process, mentioned earlier, has four parts, called DORA for short, which include: Discover, Offer, Request, and Acknowledgement. The Discover part of this packet list is called that because you as the client are trying to 'discover' a DHCP server by sending out a big ping to your entire network. You'll also notice at this stage that you don't have an IP address - it'll just be Your discover packet will say Boot request 1 in the Message type area, address fields will say, and there's a bunch of info in the Options area. It says it's a DHCP Discover packet, then you have a client identifier, the requested IP address, and a Parameter request which will list other items the client wants to know from the DHCP server, like the IP addresses of other stuff on the network. The next packet, the Offer, is from the DHCP server coming to the client. It's as if the server is 'offering to communicate and give the client an IP address'. But how does it find the client? With it's hardware MAC address! Yay ARP! This time the packet is a reply. Under Options, you'll see it's listed as a DHCP Offer, with a subnet mask, a renewal time, rebinding time, an IP address lease time, and an identifier for the server. From here you will send out a request packet. This packet tells the server that the client approves the info offered up. This one still has as the client ip address because you haven't completed the acceptance yet, and the Options will say DHCP request. Finally, you'll see an acknowledgement packet, which is sent from the server with the new IP address for the client, and then that new IP address is finally recorded in it's database. Back when we mentioned that lease time thing, that has to do with a packet called an "In-Lease Renewal". When the client has used an IP address for an allotted amount of time, it must tell the server it wants an in-lease renewal. This'll start a truncated version of the DORA packets. Lastly, a note on the DHCP options. You can find a listing of these at the IANA.org website along with Bootstrap protocol parameters (bootstrap was used back in the day to assign IP's to devices before DHCP was created). If you scroll down to Options, there are mainly 8 of them that you might see in Wireshark. These are pretty self-explanatory so I won't go into details. Let me know what you think. Send me a comment below or email us at [email protected] And be sure to check out our sister show, Hak5 for more great stuff just like this. I'll be there, reminding you to trust your technolust. -~-~~-~~~-~~-~- Please watch: "Bash Bunny Primer - Hak5 2225" https://www.youtube.com/watch?v=8j6hrjSrJaM -~-~~-~~~-~~-~-
Views: 13144 Hak5
Network Signatures
Summary Signature analysis, brief introduction to the Snort IDS, analysis of ICMP packet capture, common TCP/UDP ports, network baselining, the TCP 3-way handshake, and review of TCP flags. 3:26 - Example of Snort IDS rules 9:45 - md5sum usage 14:45 - ifconfig command in Linux 15:22 - Using tcpdump for packet capturing 17:05 - Viewing packet captures with tcpdump 20:09 - Examining ICMP packet captures 20:54 - Using ipconfig in Windows 23:20 - Well known port numbers 27:19 - Examining the TCP 3-way handshake in packet captures Reference Materials Guide to Network Defense and Countermeasures - Chapter 4 Wireshark 1.9 manual: https://cet4663c.pbworks.com/w/file/62450910/4663_Wireshark_manual.pdf The Great Debate: Network vs Protocol Analysis: http://www.symantec.com/connect/articles/great-ids-debate-signature-analysis-versus-protocol-analysis
TCP Flags for Wireshark
How to install my TCP Flags dissector for Wireshark http://blog.didierstevens.com/2014/04/28/tcp-flags-for-wireshark/
Views: 8965 dist67
Counter-Strike AMXModX Plugin - IP Shower [Hide Admins|Flag Control|IP Menu]
Direct download: http://adf.ly/1mhfZS This plugin adds commands, which you can use to see the IP addresses of other players. The plugin automatically hides the IPs of administrators, because nowadays players often use the so called "flood", especially against the admins. The option for IP hiding can be disabled by a cvar. A menu can be used to check the IP of a specific player. Some forums require date and time when reporting players, so this plugin will automatically display them when using a command. The commands are amx_showip and /showip. Tags: counter-strike plugins counter-strike plugin counter-strike fun plugins counter-strike ip shower plugin counter-strike ip shower counter-srtike amxmodx ip shower counter-strike amxmodx amxmodx amxmodx plugins amxmodx ip shower plugin amxmodx ip shower ocixcrom crom
Views: 1975 OciXCrom
Minecraft - Worldguard Tutorial - Professionelles protecten - Worldguard Flags - GERMAN
IP vom Server: Ts3: Soulcraft-premium.de Forum: http://soulcraft-cracked.de/forum2/ Jetzt joinen! Immer auf neuster Version! Viele Plugins, viele Update und viele Events! Seid dabei!
Views: 12853 marcohoffi
How to Hang a Tapestry in 3 Easy Ways
How to hang a tapestry on the wall in three different and easy ways, including damage-free methods for those who live in dorms or apartments. Find quality bohemian tapestries + more dorm decor at: https://shoplunarose.com/ (tapestries coming soon) Song: Forever Believe by Audionautix is licensed under a Creative Commons Attribution license (https://creativecommons.org/licenses/by/4.0/) Artist: http://audionautix.com/
Views: 265627 Amanda Love Santos
hping: installation, verbose, TCP flags, intervals
hping: installation, verbose output, setting TCP flags, traffic intervals
Views: 109 AskFrank15
Minecraft: WorldGuard Tutorial - Protect Regions, Disable PvP, and More!
Ultimate WorldGuard Tutorial! If you have any additional questions just ask :D Server IP - OmegaRealm.com Required - WorldGuard - http://dev.bukkit.org/server-mods/worldguard/ WorldEdit - http://dev.bukkit.org/server-mods/worldedit/ Bukkit - bukkit.org
Views: 814480 ZexyZek
Minecraft - World Guard Tutorial - Flags
here is the list of flags - http://wiki.sk89q.com/wiki/WorldGuard/Regions/Flags server IP - sc3.servercraft.co:6977
Views: 32957 MegaZombie101
ping tcp command in the Cisco ASA firewall
Follow our channel at http://vid.io/xomJ Visit our web page at http://vid.io/xomQ I have just realized how powerful the "ping tcp"-command is in the Cisco ASA firewall. This command really has nothing to do with pings. What the command does is to send a TCP ACK-packet to a certain destination on a specific destination port. And wait for a SYN-ACK-packet in return. in its most simple form you can run ping tcp, a destination, and a port. In my example here I send a ping tcp to www.google.com on port 443. Like other pings in Cisco devices it defaults to 5 packets sent, but this can be changed with the repeat-parameter. As we can see here we got 5 exclamation marks which means that the firewall received 5 tcp SYN-ACKS from google. But it doesn´t stop there. The command can also spoof the source adress to emulate a packet sent thru the firewall. This firewall has two interfaces, one outside and one inside. The inside is addresses In this topology there is currently no hosts on the inside. The outside is connected to internet and there is a dynamic NAT configured to hide the internal 10-network behinde the outside interface IP address. Let´s try the ping tcp-command with specifying a non-existant host on the inside. I run the command "ping tcp inside www.google.com 443 source 12345". I specify the inside interface in the command to tell the firewall that the packet comes from the inside interface. The 12345 in the end is the source port of the packet, the port number that in most cases is randomly selected by the source device. I run the command and get 5 replies back. That is good. But what really happened? I have a packet-capture running in the background recording packets on the outside interface. If we look at the result from the capture we can see that there was packet sent out, and received. Note that the source address of our outbound tcp-packets are the outside interface address of the firewall, because of the NAT. I have also verified with a packet-capture on the inside interface of the firewall that the SYN-ACK packets are not sent out on the inside interface. So what this commands does is to spoof the source address of the outbound TCP SYN-packet. It recognizes and presents the return-packet and do NOT send the return packet back to the spoofed source address. If I break the NAT-configuration of the firewall I can see that the ping does not get any replies back. Looking at the packet-capture on the outside shows that this is because the NAT-configuration is really used. Now the source-address is really the private 10-address and that´s why the return packet cannot find its way back to the firewall. The conclusion I draw from this is that the outbound packet is actually injected in the traffic flow bEFORE the NAT and access-list filtering instances. So it can be used to troubleshoot all kind of issues with the traffic flow, including bad ACL and NAT configuration. I really recommend you to play around with this command and have is as one of your troubleshooting tools. I will! Thanks for watching this video. Please visit my web site nat0.net for more network security related topics. See you!
Views: 4066 nat0.net
TCP Connection Management Part 1 | IIT Lecture Series
TCP is a unicast connection-oriented protocol. Before either end can send data to the other, a connection must be established between them. TCP detects and repairs essentially all the data transfer problems that may be introduced by packet loss, duplication, or errors at the IP layer (or below). Because of its management of connection state (information about the connection kept by both endpoints), TCP is a considerably more complicated protocol than UDP. During connection establishment, several options can be exchanged between the two endpoints regarding the parameters of the connection. Some options are allowed to be sent only when the connection is established, and others can be sent later. The TCP header has a limited space for holding options (40 bytes).
Views: 37264 CSE Technical Videos
EXPLAINED: TCPDUMP and How to Sniff and Analyse tcp packet (Step-by-step Guide)
TCPDUMP is a very powerful command-line packet sniffer tool used to sniff and analyse packets moving through the network. In this video how can we use this tool and also how to analyse tcp traffic. TCPDUMP is available by default in kali linux OS. If you are using some other distro of Linux and do not have tcpdump installed, you can install it by typing the following command into the terminal: sudo apt-get install tcpdump TCPDUMP even capture username/password that a user provide to a "http" website i.e without SSL or TLS.
Views: 37548 XPSTECH
Packets in Networking (Part 2) - Example of IP Datagram
Following the intro to packets in the previous part, I give an example of a real packet, and IP datagram, looking at the structure of the header. Given on 2 September 2013 at Bangkadi, Pathumthani, Thailand by Steven Gordon. http://sandilands.info/sgordon/teaching
Views: 39144 Steven Gordon
ifconfig - linux
ifconfig (short for interface configuration) is a system administration utility in Unix-like operating systems to configure, control, and query TCP/IP network interface parameters from a command line interface (CLI) or in system configuration scripts. Ifconfig originally appeared in 4.2BSD as part of the BSD TCP/IP suite. Ifconfig is used to configure the kernel-resident network interfaces. It is used at boot time to set up interfaces as necessary. After that, it is usually only needed when debugging or when system tuning is needed. If no arguments are given, ifconfig displays the status of the currently active interfaces. If a single interface argument is given, it displays the status of the given interface only; if a single -a argument is given, it displays the status of all interfaces, even those that are down. Otherwise, it configures an interface.
Views: 16974 Edik Mkoyan
IPv4 Header Format| Explained Every field of Header |  Computer Networks
IPv4 Header Format| Explained Every field of Header | Computer Networks This video explains the IPv4 header format. Every field of header is explained in detail. Internet Protocol version 4 (IPv4) is the fourth revision in the development of the Internet Protocol (IP) and the first version of the protocol to be widely deployed. Together with IPv6, it is at the core of standards-based internetworking methods of the Internet Internet Protocol being a layer-3 protocol (OSI) takes data Segments from layer-4 (Transport) and divides it into packets. IP packet encapsulates data unit received from above layer and add to its own header information. Version: Version no. of Internet Protocol used (e.g. IPv4). IHL: Internet Header Length; Length of entire IP header. DSCP: Differentiated Services Code Point; this is Type of Service. ECN: Explicit Congestion Notification; It carries information about the congestion seen in the route. Total Length: Length of entire IP Packet (including IP header and IP Payload). Identification: If IP packet is fragmented during the transmission, all the fragments contain same identification number. to identify original IP packet they belong to. Flags: As required by the network resources, if IP Packet is too large to handle, these ‘flags’ tells if they can be fragmented or not. In this 3-bit flag, the MSB is always set to ‘0’. Fragment Offset: This offset tells the exact position of the fragment in the original IP Packet. Time to Live: To avoid looping in the network, every packet is sent with some TTL value set, which tells the network how many routers (hops) this packet can cross. At each hop, its value is decremented by one and when the value reaches zero, the packet is discarded. Protocol: Tells the Network layer at the destination host, to which Protocol this packet belongs to, i.e. the next level Protocol. For example protocol number of ICMP is 1, TCP is 6 and UDP is 17. Header Checksum: This field is used to keep checksum value of entire header which is then used to check if the packet is received error-free. Source Address: 32-bit address of the Sender (or source) of the packet. Destination Address: 32-bit address of the Receiver (or destination) of the packet. Options: This is optional field, which is used if the value of IHL is greater than 5. These options may contain values for options such as Security, Record Route, Time Stamp, etc.
How Checksum is calculated in IP packets at Network Layer
A checksum is a simple error-detection scheme in which each transmitted message that results in a numerical value based on the value of the bytes in a message. The sender places the calculated value in the message (usually in the message header) and sends the value with the message. The receiver applies the same formula to each received message and checks to make sure the accompanying numerical value is the same. If not, the receiver can assume that the message has been corrupted in transmission. This video will show you how checksum is calculated for IP packets at network layer.
Views: 13982 HowTo
How to practice your hacking skills with Capture the Flags VM's
Visit https://bugcrowd.com/jackktutorials to get started in your security research career! Visit JackkTutorials.com for more content! Including Blogs, Forums and Downloads. In this video we take a look at practicing our hacking skills with Capture the Flag VM's and websites set up specifically to be broken ▂▃▅▆▇█ Resources used in this video █▇▆▅▃▂ VulnHub - https://www.vulnhub.com/ BugCrowd Researcher Resources - http://bit.ly/2aJHhqB HackSplaning - https://www.hacksplaining.com/exercises amanhardikar - http://www.amanhardikar.com/mindmaps/Practice.html ▂▃▅▆▇█Contact Details █▇▆▅▃▂ Email (Jackk): [email protected] Website: http://www.jackktutorials.com Forums: http://www.jackktutorials.com/forums Remember to Like, Comment and Subscribe if you enjoyed the video! Also share if you know someone who would also like this video! Please disable Adblock to help me and other YouTubers out!
Views: 192188 JackkTutorials
Minecraft - How To Make A Flag
Minecraft - How To Make A Flag! Today I'm going to show you how to make a nice and easy Minecraft Flag. This Minecraft Flag will look great in all of your houses and should look a lot better than the standard Minecraft Flag designs you are used to. In this Minecraft Tutorial series, I will be showing you cool things to build in Minecraft and clearly breaking it down step by step, showing how to make nice/cool designs just like the Minecraft Flag design in this video. The Minecraft Flag should work for all versions of Minecraft such as XBOX, PS4, PS3, MCPE, Wii U & PC. If you have any questions about this Minecraft Flag tutorial or have a Minecraft Flag design of your own, please feel free to put it in the comment section down below. Also, I would like to give a Big thank you to Epica for working with me with this Minecraft Flag Design. I hope you enjoy this tutorial of Minecraft - How To Make Flag :) ● Facing East ► /summon armor_stand ~0.625 ~-2 ~-0.25 {Invisible:1b,NoBasePlate:1b,NoGravity:1b,ShowArms:1b,Rotation:[180f],Pose:{LeftArm:[360f,0f,0f]}} ● Facing West ► /summon armor_stand ~-0.625 ~-2 ~0.25 {Invisible:1b,NoBasePlate:1b,NoGravity:1b,ShowArms:1b,Pose:{LeftArm:[360f,0f,0f]}} ● Facing South ►/summon armor_stand ~0.25 ~-2 ~0.625 {Invisible:1b,NoBasePlate:1b,NoGravity:1b,ShowArms:1b,Rotation:[270f],Pose:{LeftArm:[360f,0f,0f]}} ● Facing North ► /summon armor_stand ~-0.25 ~-2 ~-0.625 {Invisible:1b,NoBasePlate:1b,NoGravity:1b,ShowArms:1b,Rotation:[90f],Pose:{LeftArm:[360f,0f,0f]}} ● Remove Armor Stands ► /kill @e[type=armor_stand,c=1] ● Command Block Command ► /give (name) minecraft:command_block ● Join Team Biggs! ► http://bit.ly/TeamBiggs ● Minecraft Flag Playlist ► https://www.youtube.com/playlist?list=PLATczsrjFTph28NHbyIgCNvLOyMWOdvih ------------------------------------ .:My Info:. ● 2nd Channel ► https://www.youtube.com/RickyandZai ● Snapchat: itsbiggs87x ● Twitter: http://twitter.com/biggs87x ● Facebook: http://www.facebook.com/Biggs87x ● Instagram: http://instagram.com/biggs87x/# ● TwitchTV: http://www.twitch.tv/biggs87x ----------------------------------- .:Minecraft Server Info:. ● Fan Server IP ► mc.kaoshkraft.net ● Kaoshkraft Website ► http://www.kaoshkraft.net/ ● Get 70% a Minecraft server when you use code "kaoshkraft" ► http://bit.ly/Envious_Host --------------------------------------- Title ► Minecraft - How To Make A Flag ------------------------------------ Thanks for all your support on this Minecraft - How To Make A Flag. Rating the video and leaving a comment is always appreciated! - Biggs87x ------------------------------------- What is Minecraft? Minecraft is an online virtual playground and workshop, where kids of all ages can safely interact, create, have fun, and learn. It’s unique in that practically everything on Minecraft is designed and constructed by members of the community. Minecraft is designed for 8 to 18 year old, but it is open to people of all ages. Each player starts by choosing an avatar and giving it an identity. They can then explore Minecraft — interacting with others by chatting, playing games, or collaborating on creative projects. Each player is also given their own piece of undeveloped real estate along with a virtual toolbox with which to design and build anything — be it a navigable skyscraper, a working helicopter, a giant pinball machine, a multiplayer “Capture the Flag” game or some other, yet ­to ­be ­dreamed-up creation. There is no cost for this first plot of virtual land. By participating and by building cool stuff, Minecraft members can earn specialty badges as well as Minecraft dollars (“Minecraft”). In turn, they can shop the online catalog to purchase avatar clothing and accessories as well as premium building materials, interactive components, and working mechanisms.
Views: 69361 Biggs87x
Quick Configs - IPv6 DHCPv6 (stateful, stateless, relay, managed-config-flag, other-config-flag)
This CCIE oriented episode of quick configs goes into the Dynamic Host Configuration Protocol for IPv6 (DHCPv6). See http://bit.ly/1VZYkFi for all CCIE notes.
Views: 9918 Ben Pin
Analyzing the tcpdump data
This video is part of the Udacity course "Networking for Web Developers". Watch the full course at https://www.udacity.com/course/ud256
Views: 3250 Udacity
Explicación de FLAGS y protocolo tcp
Views: 111 Sebastian Molina S
2b BW BibleWorks Option Flags, cont
Watch in HD, fullscreen. Continued from 2 BW, now 'Command Line Configuration Options' through 'Verse List Checkboxes', going straight down the list of options in the Option Flags listing. Sidetrips taken on searching and basics on tab storage.
Views: 91 Brain Outy
Drop port scanners with MikroTik
Drop port scanners with MikroTik Блокирование ip адресов сканирующи сеть с помощью микротика. Для этого необходимо добавить несколько правил в фильтры. add chain=input protocol=tcp psd=21,3s,3,1 action=add-src-to-address-list address-list="port scanners" address-list-timeout=2w comment="Port scanners to list " disabled=no add chain=input protocol=tcp tcp-flags=fin,!syn,!rst,!psh,!ack,!urg action=add-src-to-address-list address-list="port scanners" address-list-timeout=2w comment="NMAP FIN Stealth scan" add chain=input protocol=tcp tcp-flags=fin,syn action=add-src-to-address-list address-list="port scanners" address-list-timeout=2w comment="SYN/FIN scan" add chain=input protocol=tcp tcp-flags=syn,rst action=add-src-to-address-list address-list="port scanners" address-list-timeout=2w comment="SYN/RST scan" add chain=input protocol=tcp tcp-flags=fin,psh,urg,!syn,!rst,!ack action=add-src-to-address-list address-list="port scanners" address-list-timeout=2w comment="FIN/PSH/URG scan" add chain=input protocol=tcp tcp-flags=fin,syn,rst,psh,ack,urg action=add-src-to-address-list address-list="port scanners" address-list-timeout=2w comment="ALL/ALL scan" add chain=input protocol=tcp tcp-flags=!fin,!syn,!rst,!psh,!ack,!urg action=add-src-to-address-list address-list="port scanners" address-list-timeout=2w comment="NMAP NULL scan" add chain=input src-address-list="port scanners" action=drop comment="dropping port scanners" disabled=no
Views: 2184 Mik Sys
Polylang Multilingual WordPress Plugin 2017 Step-by-Step Install and Setup
Grab Your Free 17-Point WordPress Pre-Launch PDF Checklist: http://vid.io/xqRL Create a Multilingual WordPress site with Polylang tutorial - https://youtu.be/YpFdmzWCFRc Exclusive for WPLearningLab viewers, up to 50% off hosting: https://wplearninglab.com/wordpress-hosting-offer/ Polylang multilingual WordPress plugin allows you to convert your website into a multi-language WordPress site. This will allow you to reach a wider audience with your content. You will have to the translations yourself or you can hirer translators that integrate directly with the plugin. First things first, let's install the plugin. To install this plugin please log into your WordPress dashboard, hover over Plugins and then click on Add New. On the next page type "Polylang" into the search bar. The plugin we want should be the first one in the top left. The image looks like a parrot's head facing to the right. Click on the Install Now button and then click Activate after it's installed. There are a lot of add-ons for the Polylang plugin. I encourage you to check those out if you need additional multi-language functionality. This plugin allows you to add languages to your site in the plugin settings. By adding a language, it adds functionality to translate any post to that language and adds that language to the sidebar widget. To add languages click on Languages in the lefthand admin menu. On the next page is a simple form that will allow you to add more languages. Add as any as you want. But keep in mind the plugin does not automatically translate your content. All translations are manual. Now that you've added languages click on Posts or Pages in the left side admin menu to those lists. You will see new columns with the country flags of the languages you chose in the header row. In each post or page row you will see either a check mark, a plus sign or a pencil under any given specific country flag. The check mark means that the post in that row is in that language. The pencil means a translation in that language exists and you click on the pencil to edit it. The plus sign means that a translation does not yet exist in that language. You can click the plus sign to create a version for that language. It's important to keep in mind that when a post is translated into all the languages you chose, there will be a separate post for each language. For example, if you have 3 different languages set for your site, if you translate a post into all of those languages you will 3 different posts. One for each language. Once you have some posts translated you'll want to add the sidebar widget to your site so that people can switch between languages. Go to Appearance, then Widgets. In the Available Widgets section there will be one called Language Switcher. Drag it to your sidebar and then customize it. Once you're done, go to a blog post on your site and switch languages using the switcher to see how it works. It's pretty cool. By default, the plugin will detect the visitor's browser's language and pick that language on your site if it exists. You can change that behavior if you go to Languages, then Settings. There is more to the Polylang plugin but this will get you started on the right foot. I hope this information helps you! If you have any questions leave a comment below or ping me @WPLearningLab on Twitter. -------------- If you want more excellent WordPress information check out our website where we post WordPress tutorials daily. https://wplearninglab.com/ Connect with us: WP Learning Lab Channel: http://www.youtube.com/subscription_center?add_user=wplearninglab Facebook: https://www.facebook.com/wplearninglab Twitter: https://twitter.com/WPLearningLab Google Plus: http://google.com/+Wplearninglab Pinterest: http://www.pinterest.com/wplearninglab/
TCP connection walkthrough | Networking tutorial (13 of 13)
Walk through TCP connection and termination packet by packet. Support me on Patreon: https://www.patreon.com/beneater This video is part 13 of an intro to networking tutorial: https://www.youtube.com/playlist?list=PLowKtXNTBypH19whXTVoG3oKSuOcw_XeW Want to see more? Leave a comment!
Views: 201269 Ben Eater
tcpdump: filters: tcp three-way handshake
tcpdump: packet captures using TCP flags such as SYN, SYN-ACK, and ACK
Views: 544 AskFrank15
Banner Stakes Magnetic Wall Mounts
Banner Stakes Wall Mount Retractable Barriers Provide Barricade Options For Indoor Applications Including Construction, Industrial, Commercial And More. Banner Stakes Wall Mount Retractable Barriers are made of polyester and plastic for long lasting durability. Barriers are surface mounted for blockade use in hallways, restrooms, elevators and more. Available types are 7' Magnetic Wall Mount Barrier, 30' Magnetic Wall Mount Barrier, Plus Wall Mount Set and Wall Mount. Messages include Authorized Personnel Only, Caution, Caution - Do Not Enter, Cleaning In Progress, Danger - Forklift Traffic, Danger - Keep Out, Danger High Voltage Keep Out, Do Not Enter - Arc Flash Boundary and more. Available colors include Orange, Red and Yellow. OSHA compliant. Dimensions vary per model. http://goo.gl/NS3qnH
Views: 748 Global Industrial
Introduction to Crafting Network Packets with Scapy
Author: Jeremy Druin Twitter: @webpwnized Thank you for watching. Please support this channel. Up vote, subscribe or even donate by clicking "Support" at https://www.youtube.com/user/webpwnized! Description: Recorded at the KY ISSA November 2016 Lunch and Learn meeting. This video is a quick introduction to crafting network packets with the Python Scapy tool in Kali Linux. It is intended to help beginners get up to speed using Scapy so they can explore Scapy from that point.
Views: 10287 webpwnized
Minecraft WorldGuard Tutorial (How To Protect Your Spawn, Enable PVP, & More!)
How do you setup WorldGuard to protect your spawn, get a PVP area, and much more? Well, that is exactly what I show you in the video. I go through everything from how to define a WorldGuard region to how to add spawn protection to your Minecraft server. I cover it all! Setup Your Server with ApexMinecraftHosting! https://TheBreakdown.xyz/ApexNetwork Download WorldGuard: https://TheBreakdown.xyz/WorldGuard Download World Edit: https://TheBreakdown.xyz/WorldEditPlugin World Guard Flags: https://TheBreakdown.xyz/WorldGuardFlags -------------------------------------------------------- ★ Minecraft Server IP: Play.BreakdownCraft.com ► Store: http://Store.BreakdownCraft.com/ ★ Join BreakdownCraft on Discord!: https://BreakdownCraft.com/Discord -------------------------------------------------------- ► Subscribe!: https://TheBreakdown.xyz/YTSub -------------------------------------------------------- Start A Network Server!: https://TheBreakdown.xyz/StartAServerNetwork Get A 1.13.2 Server w/ Plugins: https://youtu.be/fFz57jhMxB0 -------------------------------------------------------- **FOLLOW US ON SOCIAL MEDIA** Our Website: https://TheBreakdown.xyz Facebook: https://Facebook.com/BreakdownHowTo Twitter: https://Twitter.com/BreakdownHowTo Email: [email protected] -------------------------------------------------------- ★ Recommended Gear Get your C920 Webcam: https://TheBreakdown.xyz/c920 Get your #Minecraft Server: https://TheBreakdown.xyz/MCServer Get your Blue Snowball: https://TheBreakdown.xyz/Snowball -------------------------------------------------------- Music From EpidemicSound: http://TheBreakdown.xyz/EpidemicSound About this video: In this video, I show you everything from how to download and install World Guard in Minecraft to how to get WorldGuard setup on your server. Everything is covered here, so no matter what you are looking to do with WorldGuard, This video will show you exactly how to do it! First things first, we need to download and install #WorldGuard on our #MinecraftServer. This is very easy. You can find the WorldGaurd Download link above. You will also need to download WorldEdit as World Guard needs World Edit for it to work. After you have these downloaded and installed on your server, jump on in the game. Once you are in game, you need to use WorldEdit to make a section this can be anything you want just make sure to expand the region vertically with //expand vert if you want bedrock to world height protected. After you have your region selected and expanded, you need to create a WorldGuard region. To do this, just do /region define [regionname]. This will create a World Guard region and in doing so protect the entire region from other players breaking blocks. Now, we have our spawn protected with World Guard. What about creating a PVP area? You can use WorldGuard to do this too. First things first, you will need to create another region using the steps above. Then, we need to set a region flag. You can find a link to all of the WorldGaurd region flags above. The command to set a region flag is /region flag [regionname] [regionflag] [allow/deny]. Once you have setup your region flags, for PVP, for example, you will have used World Guard to its fullest! And there you have it. That is our complete guide to setting up WorldGuard on your Minecraft server. If you have any questions, please let us know if the comment section down below, and be sure to give this video a thumbs up if you haven't already. It really helps us out, and it means a ton to me. Thank you very, very much in advance! Note: Some of the above links are affiliate links. I may receive a commission at no additional cost to you if you go to these sites and make a purchase.
Views: 819 The Breakdown
Netstat for Tracking Detailed Network Statistics (6/14)
Let's take a look at the netstat command on Linux and how to use it effectively.
Views: 2916 Joseph Delgadillo
Query DNS Server using DIG
Query DNS Server using DIG This tutorial will show you how to query a Domain Name System (DNS) name servers for records, and how to specify which DNS server to query, using the DIG (domain information groper) command-line tool. Using the DIG command-line tool, you can find DNS records for different domain names, such as google.com, bing.com, and hotmail.com, and you can query different DNS servers, such as Google's public DNS server." From the DIG command-line tool prompt, run "dig google.com." You will see the DIG command output. Look at the "ANSWER SECTION," which shows you the answer (it displays "A" records of google.com) Unless otherwise specified, the DIG command-line tool displays "A" records by default. You can also query specific records using DIG command, for example, a MX record. From the command prompt run "dig google.com MX." You will see that the ANSWER SECTION displays the MX records and the "ADDITIONAL SECTION" displays "A" records of Google's MX hosts. You can also query Name Servers or (NS) records. Simply use the NS type in your query. Run "dig google.com NS" at the command prompt. The output is displayed in the "ANSWER SECTION," and the "ADDITIONAL SECTION" displays "A" records of Google's name servers. If you, for example, want to know the name of some host and all you have is its external IP address, you can do it by performing a reverse DNS lookup, using "dig x". In the command prompt, run "dig x" The "ANSWER SECTION" will display the host name that belongs to the IP address, which is one of Google's public DNS servers. If you want to use a different DNS server to perform the query, you can do it by specifying the DNS server in the command line. By default, DIG uses servers defined in the /etc/resolv.conf configuration file. If you run, "dig @ bing.com," the "ANSWER SECTION" displays an "A" record for bing.com domain. In the stats section below that, "SERVER:" displays what DNS server you queried directly. You can use this method to find answers for any type of DNS records For example, you can query Google's public DNS server for a TXT record of hotmail.com domain. In the command prompt, if you run [email protected] hotmail.com TXT, the "ANSWER SECTION" will display hotmail's TXT records. For more information about the DIG command-line tool and a list of detailed options available, at the command prompt, run "man dig."
Views: 2177 Superb Marketing
REACHING 2000 CAPS! - Capture the Flag #4
In this episode, I reach a milestone of 2,000 captured flags on MCC! Something only achieved by a handful of people! I hope you guys enjoy this episode, make sure to leave a like, and subscribe please! :) MC-Central IP: mc-central.net
Views: 551 tylertacobell
CLSID Scam Phone Call Trolling
So I received a call from the "help and support centre" stating that my ip address is giving warning flags. They claim that there are warning flags because my computer is infected with malware that is preventing certain "services" to work. I knew this was complete bullcrap, so I placed my phone on speaker beside my microphone and recorded it. Note: The CLSID Scam is based on tactics of fear, where first they would lead you to a log that Windows keeps of errors. They would claim that these errors are from the malware preventing Windows from working properly. However these errors would probably have occurred anyways if there wasn't any malware. (I prevented them from doing this step to me) Second, they would lead me to access "assoc" through "cmd (Command Prompt)". "assoc" is meant to edit what file extensions associate with what file type. For example, a .txt would associate to a plain text file and a .jpeg would associate to a type of image file called Joint Photographic Experts Group. More importantly, they want to confirm your "computer-id" through the CLSID which is at the end of the command prompt if you type "assoc" into it. It usually looks like this: .zfsendtotarget=CLSID\{ 888DCA60-FC0A-11CF-8F0F-00C04FD7D062}. Now if your CLSID is the same as mine, don't worry for this CLSID number is not as unique as the scammer claims it is. However the scammer tactic is to make you think that they are legit by magically reciting that common number. People that aren't that familiar with computers would probably fall into this trap. Then the damage starts. Once the scammer believes that you have been fooled, he (in my case she) transfers you to a "rescue department with "Microsoft Certified" technicians to screw you - I mean - help you with your non-existent malware problems. They make you give him (English is strange where him also can be her) remote access with AMMYY or LetMeIn. God knows what happens you let this happen. If you enjoyed the video, leave a like or comment!
Views: 14183 Legendofham
3.2 Network port scanning
Module 3 – Network scanning. Section 3.2: Port scanner A port scanner is an application designed to probe a server or host for open ports. • This is used by admins to verify security policies of a network and by attackers to identify network services running on a host and exploit vulnerabilities. • Portsweep is to scan multiple hosts for a specific listening port. Well-known port numbers • 21: FTP 22: SSH 23: Telnet • 25: SMTP 110: POP3 • 143: IMAP 53: DNS service • 123: NTP 161: SMP • 80: HTTP 443: HTTP Secure (HTTPS) Scan results In TCP/IP network services are referenced using two components: a host address and a port number. Ex. (host:port) The result of a scan on a port is usually generalized into one of three categories: – Open or Accepted – Closed or Denied or Not Listening – Filtered, Dropped or Blocked Ports threats • Open ports present two vulnerabilities: – Security and stability concerns associated with the program responsible for delivering the service - Open ports. – Security and stability concerns associated with the operating system that is running on the host - Open or Closed ports. • Filtered ports do not tend to present vulnerabilities. Scanning types – TCP scanning – SYN scanning – UDP scanning – ACK scanning – Window scanning – FIN scanning – Other scan types TCP scanning • TCP scan completes the TCP three-way handshake, and the port scanner closes the connection to avoid performing a Denial-of-service attack. Otherwise an error code is returned. • The services can log the sender IP address and Intrusion detection systems (IDS) can raise an alarm. • Nmap calls this mode connect scan, named after the Unix connect() system call. Scanning SYN scan is TCP scanning also known as "half-open scanning". • The port scanner generates a SYN packet. If the target port is open, it will respond with a SYN-ACK packet. The scanner host responds with an RST packet, closing the connection before the handshake is completed. • If the port is closed but unfiltered, the target will instantly respond with an RST packet. UDP Scanning • UDP port scanners send a UDP packet to a port and if that port is not open, the system will respond with an ICMP port unreachable message. • The absence of a response is considered that port is open. • If a port is blocked by a firewall, this method will falsely report that the port is open. • Example, sending a DNS query to port 53 will result in a response, if a DNS server is present. ACK Scanning ACK scanning does not exactly determine whether the port is open or closed, but whether the port is filtered or unfiltered. • This is especially good when attempting to probe for the existence of a firewall and its rulesets. Window scanning Window scanning is rarely used and is untrustworthy in determining whether a port is opened or closed. – It generates the same packet as an ACK scan, but checks whether the window field of the packet has been modified. FIN scanning Firewalls block generally SYN packets. FIN packets can bypass firewalls without modification. Closed ports reply to a FIN packet with the appropriate RST packet, whereas open ports ignore the packet on hand. This is typical TCP behavior and is in some ways a loophole. Other scan types • X-mas and Null Scan • Protocol scan • Proxy scan • Idle scan • CatSCAN • ICMP scan Port filtering by ISPs • Many ISPs restrict their customers' ability to perform port scans to destinations outside of their home networks. • Some ISPs implement packet filters or transparent proxies that prevent outgoing service requests to certain ports.
Views: 3463 CBTUniversity
mcpe indonesia server capture the flag
Ip server:ctf.lbsg.net Mohon like dan subscribe
Views: 87 Ardine Craft
IP Datagram
Views: 253 Anc Chaimongkon

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