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Internet Protocol, Transport Control Protocol, Network protocols, Routing, Routers, IP aliases, Routes, Ethernet

 [ Total topics 58 Go to page 1, 2, 3, 4, 5, 6

 Post subject: Problem pinging and using server with mobile hotspot
PostPosted: Mon Oct 23, 2017 10:19 pm 
I have eliminated the cost of Isp by getting an unlimited mobile sprint ZTE hotspot. I used a WiFi bridge to connect to my home router. Everything works fine for appleTV, web surfing and Echo. However I have Tablo and some home servers which I can not access remotely. I am trying to diagnose the issue. Simply using the hotspot. My IP address shows different ip addresses. One is, another site shows ipv6 address. ...

Read more : Problem pinging and using server with mobile hotspot | Views : 2073 | Replies : 0

 Post subject: TCP ack after two packets
PostPosted: Mon Jun 13, 2016 5:14 pm 
im using wireshark for tcp project.
when ACK is sent i get window size of 65536 but every two pockets in the list are followed by ACK send
isnt ACK sent after receiving 65536 bytes?
some times the window sie jump and the goes back to 63k
what cause it to happend?

bloody hell tcp

Read more : TCP ack after two packets | Views : 2594 | Replies : 2

 Post subject: IP Subnetting Raneg Assigning...?
PostPosted: Tue May 31, 2016 12:02 pm 
Hi All,

I'm a bit confused about assigning IP address from IP Ranges.

I am using this scenario below to understand.

Scenario an international IT solutions company, is launching 12 new branches in a new country where they currently have no existing branches. The sWin CIO has asked that each subnet should host at least 1000 devices.

sWin has obtained a network address of This address needs to be subnetted further. The internal ...

Read more : IP Subnetting Raneg Assigning...? | Views : 1831 | Replies : 0

 Post subject: TCP receive window size doesnt change
PostPosted: Wed May 25, 2016 3:36 pm 
im about to make experiment in TCP receive window size as chours project.
i im trying to check receive window size behaivior as function of number of current download
unluckily... the calculated window size didnt change at all...
after i lost my sane i connected my pc to my smartphone by hotspot and then window size changed in every pocket
my questions is:
1) what was the diffrent between the two download ways that ...

Read more : TCP receive window size doesnt change | Views : 1734 | Replies : 0

 Post subject: TCP Ack Flooding
PostPosted: Tue Mar 22, 2016 4:27 am 
Please let me know what is expected from router when TCP - ACK packets are pumped with some random sequence number into it without establishing any connection.

Read more : TCP Ack Flooding | Views : 2169 | Replies : 1

 Post subject: PTP/IP. Picture transfer protocol
PostPosted: Sun Nov 29, 2015 6:38 pm 
Hi Folks,
I'm new to all this complicated stuff so I'm not sure if this is the right place to ask my pile of stupid questions..... First one being. What differentiates tcp and ptp The first part of a packet is tcp so what makes it different. Just its length ???


Read more : PTP/IP. Picture transfer protocol | Views : 2215 | Replies : 0

 Post subject: Understanding pcap-filter/tcpdumps 'localnet' background
PostPosted: Thu Oct 01, 2015 3:10 pm 
Hello !
In all tcpdump docs, one can find this - or a similar - line:

To select traffic neither sourced from nor destined for local hosts (if you gateway to one other net, this stuff should never make it onto your local net).

ip and not net localnet

I really needed some time to find out, that the mentioned 'localnet' must be in '/etc/networks' - which was not the case for me, ...

Read more : Understanding pcap-filter/tcpdumps 'localnet' background | Views : 1833 | Replies : 0

 Post subject: ERROR: trying to remove VLAN -:791:- error: Invalid argument
PostPosted: Tue May 12, 2015 6:07 am 
Linux uses "vconfig" utility (vlan package) to add and remove vlans on interfaces in router-on-a-stick manner. Here is the vconfig help:
# vconfig
Expecting argc to be 3-5, inclusive. Was: 1

Usage: add [interface-name] [vlan_id]
rem [vlan-name]
set_flag [interface-name] [flag-num] [0 | 1]
set_egress_map [vlan-name] [skb_priority] [vlan_qos]
set_ingress_map [vlan-name] [skb_priority] [vlan_qos]
set_name_type [name-type]

* The [interface-name] is the name of the ethernet card that hosts
the VLAN you are talking about.
* The vlan_id is ...

Read more : ERROR: trying to remove VLAN -:791:- error: Invalid argument | Views : 3296 | Replies : 0

 Post subject: How to accept IPv6 Router Advertisements on interface in FreeBSD
PostPosted: Wed Apr 29, 2015 3:54 am 
# ifconfig em0 inet6 accept_rtadv

# ifconfig em0
em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
        ether 00:0c:29:d7:77:5d
        inet netmask 0xffffffe0 broadcast
        inet6 fe80::20c:29ff:fed7:775d%em0 prefixlen 64 scopeid 0x1
        media: Ethernet autoselect (1000baseT <full-duplex>)
        status: active

ifconfig em0 inet6 -ifdisabled

Notice the "ACCEPT_RTADV" in neighbor descovery ipv6 (nd6) section.

Read more : How to accept IPv6 Router Advertisements on interface in FreeBSD | Views : 3500 | Replies : 0

 Post subject: Linux script for interface network bandwidth monitoring
PostPosted: Mon Feb 09, 2015 7:05 pm 
This is a simple script that gets RX / TX values of an interface from /sys pseudo filesystem and calculate difference between current and old values displaying a bandwidth output for kilobytes per second.

INT="1" # every INT seconds

while true
RX1=`cat /sys/class/net/$1/statistics/rx_bytes`
TX1=`cat /sys/class/net/$1/statistics/tx_bytes`
sleep $INT
RX2=`cat /sys/class/net/$1/statistics/rx_bytes`
TX2=`cat /sys/class/net/$1/statistics/tx_bytes`
TXBPS=`expr $TX2 - $TX1`
RXBPS=`expr $RX2 - $RX1`
TXKBPS=`expr $TXBPS / 1024`
RXKBPS=`expr $RXBPS / 1024`
echo "TX $1: $TXKBPS kb/s ...

Read more : Linux script for interface network bandwidth monitoring | Views : 3498 | Replies : 0

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