Hot answers tagged tcpip
42
It's not MS it is the ISOC ;-)
Have a look at reserved IP address RFC 5735 under special use IPv4:
here
169.254.0.0/16 - This is the "link local" block. As described in
[RFC3927], it is allocated for communication between hosts on a
single link. Hosts obtain these addresses by auto-configuration,
such as when a DHCP server cannot be ...
37
The short answer
An Internet spec called RFC 1918 reserved a few blocks of addresses for "private" networks, which is what you should use when you don't have enough public, routable IP addresses to go around. 192.168/16 was one of those blocks.
The long answer (and then some)
Back in the good old days, everything on the Internet got its own public, ...
33
The use of 169.x.x.x addresses are defined within a standard colloquially known as APIPA - Automatic Private IP Addressing.
In a nutshell, if a network device has not been assigned a fixed (static) address and cannot obtain one by asking (DHCP), the device says to itself, "Well, I'd better make up an address of my own so I can communicate on this network", ...
22
A port isn't open if something isn't listening for a connection on it.
The reason it is bad form to have all ports open to everywhere is that it exposes those services that are listening on those ports to exploits. That is why firewalls exist, to limit what is allowed to connect to certain ports, to reduce the surface area exposed by services.
EDIT
To ...
16
For Windows 7, Windows Vista and Windows XP, the MTU for various interfaces is available from Windows itself using netsh.
Windows 7, Windows Vista
To show current MTU on Windows 7 or Windows Vista, from a command prompt:
C:\Users\Ian>netsh interface ipv6 show subinterfaces
MTU MediaSenseState Bytes In Bytes Out Interface
---------- ...
15
In IPv4: Nope. They will see the MAC of the device which forwarded the packet to the server, likely their border router.
In IPv6, the 64 bit "host" part of the full 128 bit address is often automatically generated from the MAC address, and hence might be visible to the server one connects to. See also How to avoid exposing my MAC address when using IPv6?
14
The TCP connection limit is not enforced, but it may be bound by legal agreement to not permit more than 10 clients.
See this from Microsoft: Inbound connections limit in Windows XP
In a command prompt type:
net config server
This shows max allowed logged on users, and max open files per session
13
If you are on a Windows machine, open a command box (Start...run...cmd), PING the target machine so you have made contact with it and then issue the command arp -a to view your local arp table, which will list IP addresses and their corresponding MAC addresses eg:
C:\Users\L3K>arp -a
Interface: 192.168.200.128 --- 0xb
Internet Address Physical ...
12
The TCP protocol guarantees accurate delivery regardless of underlying mechanisms. There is no guarantee that every protocol that it might run over will do any sort of integrity checking. SLIP, for example, has no error detection.
11
Due to the way TCP/IP works connections can not be closed immediately. Packets may arrive out of order or be retransmitted after the connection has been closed. CLOSE_WAIT indicates that the other side of the connection has closed the connection. TIME_WAIT indicates that this side has closed the connection. The connection is being kept around so that any ...
10
Skynet is a rootkit, not good. It is difficult to detect and remove.
Download and run Stubware
http://www.thestubware.com/malware_removal/skynet/
After you have rebooted to remove the skynet driver with Stubware, download and run MBAM, do a full system scan, when it is done scanning, allow it to remove anything it finds.
2 . Download, install and Update ...
10
You may be thinking of number of ports. There are 65536 ports available in the TCP in the current versions of IPv4. This is not just a Linux limitation, its part of the protocol. Your IP address identifies your machine, and the port identifies a program on your machine.
But, the number of connections isn't limited by that. A connection consists of 5 ...
10
It is a private block of IPs that aren't allowed to be routed on the public Internet and are reserved for internal use to be NATed to the outside world. The document that defines this is RFC 1918, which is enforced by IANA.
The blocks of private-use IPv4 addresses are:
10.0.0.0 /8 (any address beginning with 10.x.x.x)
192.168.0.0 /16 (any address ...
9
One easy way to edit the hosts file is using the freeware Windows program HostsMan.
HostsMan is a freeware application that lets you manage your Hosts file with ease
In Vista / Windows 7 it needs to run with administrative privileges, but it doesn't require going into safe mode.
9
Translation from a string to an address is usually performed by the POSIX function getaddrinfo(). This function first checks for a numeric IP address using inet_addr(), and if that fails it will then attempt to resolve the string as a domain name. inet_addr() interprets numbers with a leading 0 as octal, so for example 010 would become 8, and 019 would be ...
8
IPv6 is a "new" (for various definitions of "new") protocol. It has no physical manifestation, so doesn't need new wires etc.
It's quite old (in computing terms), but has only recently become mainstream due to the imminent exhaustion of IPv4 addresses. It took a while to take off as IPv4 was "good enough" for virtually all cases until now.
It needs new ...
8
One word: Netcat
Netcat is the go-to tool for this sort of thing.
You can thrash whatever port you choose with udp packets with something like:
nc -u host.example.com 53 << /dev/random
(53 is your port number)
Or you can send an actual file, or tell it to bind that port and listen as a service, or whatever you like.
8
The Windows Sysinternals Suite contains a tool called TcpView. TcpView will show you all of the connections on your machine similar to netstat. It will also allow you to close the connection or kill the process hosting the connection.
7
You could put together a script which calls whatismyip.com or similar and returns the interesting part (although such websites might not like you doing that). Generally, you're going to have to ask someone else (other computer) what your IP is, since your computer does not know. You could also possibly ask your router, but the parsing will probably be ...
7
To state Dave M's answer in another terms, your DHCP server has a problem and cannot allocate an IP address. When Windows and any other OS is configured to get an IP via DHCP and they don't get any, they automatically assign 169.254.xxx.xxx IP
6
To answer your question.
127.0.0.1 is not just a different ip address to the machine ip address, it's a different
interface as well. 127.0.0.1 should not be seen on the local network. It's a special
internal IP address for the loopback adapter.
x.x.x.x will be your ethernet card.
by the way 'localhost' is simply an entry in your hosts file that points ...
6
First, what you say is not factually correct:
Linux up to kernel version 2.6.18 uses BIC by default.
Linux kernel 2.6.19 and later uses CUBIC by default.
Linux's TCP congestion control mechanisms are pluggable, e.g. you can change them on the fily.
Windows XP and earlier uses TCP Reno (or New Reno)
Windows Vista and later also has Compound TCP, which is ...
6
Those are open DNS servers - i.e. they're on the public internet. They belong to Level 3 so are probably safe to use.
OpenDNS (note no space) is another DNS provider which has different addresses for it's public servers, which are in harrymc's post.
6
Use the -b switch as well:
-b Displays the executable involved in creating each connection or
listening port. In some cases well-known executables host
multiple independent components, and in these cases the
sequence of components involved in creating the connection
or listening ...
6
No. Having multiple network adapters on the same subnet is a totally valid configuration assuming that both the adapters connect to the same network. That's why we have subnets, after all.
So, as far as the operating system is concerned, you just have two NICs on the same network. There's no reason for it to complain about that.
You'll need to take one of ...
6
The private IP addresses were reserved in the early 1990's. IPv4 link-local addresses weren't added until 2005.
The block chosen, 169.254.0.0/16, was obtained simply by requesting a block from IANA and having one allocated through the normal allocation process. So it was essentially random, rather than engineered.
5
The first thing I do when I find connections I don't recognize is trace them.
PS C:\Users\self> tracert 212.192.255.240
Tracing route to 212.192.255.240 over a maximum of 30 hops
1 10 ms 10 ms 12 ms ... (omitted)
2 8 ms 8 ms 8 ms 110.ge-0-0-0.cr1.wdc1.speakeasy.net [69.17.83.57]
3 8 ms 8 ms 7 ms ...
5
First of all, neither it is a crisis (a replacement is readily available) and it will happen this year already. That is, the last /8 subnet will be allocated then.
Anyway, IPv4 and IPv6 can coexist quite well and for the most part this is transparent to the user. In fact, at least on Windows all recent versions actually have both IPv4 and IPv6 enabled and ...
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