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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

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 Post subject: KVM: List MAC address table and interface that learned them.
PostPosted: Sun Feb 01, 2015 6:26 am 
Kernel Virtualization Module (KVM) provides an internal switch with a physical interface or bundle as an uplink and virtual network devices (through virtio driver) as port to each virtual machine’s ethX interfaces.

List KVM mac address table:


This requires brctl command.
Quote:
brctl showmacs <brname> shows a list of learned MAC addresses for this bridge.

# brctl showmacs vmbr0
port no mac addr is local? ageing timer
1 00:00:1c:17:1c:33 no 0.11
1 00:16:c7:16:11:11 no 0.31
1 ...

Read more : KVM: List MAC address table and interface that learned them. | Views : 1472 | Replies : 0

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 Post subject: IPv6 tunnel - Debian Linux and tunnelbroker.net - IPv6 in IPv4 (ip protocol 41)
PostPosted: Sun Feb 01, 2015 4:17 am 
IPv6 tunnel between Debian Linux and tunnelbroker.net using ip protocol 41 (ipv6 encapsulation in ipv4)

There are many techniques to use IPv6 /64 or even /48 subnets when you do not own an ASN. One of them uses ipv6 tunnel brokers. These are companies that have huge ipv6 address space allocated to them and they delegate smaller blocks like the above mentioned to individual users or companies.

Tunnelbroker.net (HE) is one of these brokers that ...

Read more : IPv6 tunnel - Debian Linux and tunnelbroker.net - IPv6 in IPv4 (ip protocol 41) | Views : 1993 | Replies : 0

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 Post subject: Set up FTP PROXY via command line in Linux/FreeBSD
PostPosted: Tue Jan 20, 2015 5:01 pm 
Setting up FTP PROXY via command line in Linux/FreeBSD

Setting up FTP PROXY for command line tools in FreeBSD and Linux is the same as setting HTTP proxy: you can make use of the environment variable FTP_PROXY.

Assuming Proxy address 192.168.0.1 and port 3128, we use:

Code:
# export FTP_PROXY='http://192.168.0.1:3128'
In case the proxy requires authentication:
Code:
# export FTP_PROXY='http://username:password@192.168.0.1:3128'


To make this setting permanent, add the line to your /etc/profile or ~/.profile or ~/.(bash|sh|ksh)rc.

Removing ...

Read more : Set up FTP PROXY via command line in Linux/FreeBSD | Views : 16500 | Replies : 0

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 Post subject: Set up HTTP PROXY for shell internet access Linux/FreeBSD
PostPosted: Tue Jan 20, 2015 4:59 pm 
Setting HTTP PROXY for command line tools such as wget/fetch/pkg_add/yum/apt-get on Linux and Freebsd.

Wget/apt-get/fetch/yum/pkg_add -rv and the rest of command line tools in Linux and FreeBSD that use HTTP protocol will not use the proxy settings from your Firefox/Konqueror/Opera browsers. Instead, an environment variable "HTTP_PROXY" must be set and exported.

Assuming that your HTTP Proxy IP address is 192.168.0.1 port 3128 (standard proxy port), you must use following command (as the user you wish ...

Read more : Set up HTTP PROXY for shell internet access Linux/FreeBSD | Views : 43403 | Replies : 0

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 Post subject: Linux tso (tcp segmentation offload) - what it means and how to enable/disable it
PostPosted: Fri Jan 16, 2015 5:41 am 

Why am I seeing packets larger than MTU in tcpdump ?


You probably have seen at least one a wireshark or tcpdump showing some strange packet sizes, way over the regular legitimate MSS and MTU values ( 1460 and 1500 bytes for Ethernet).

Before you begin, read: How the Linux TCP output engine works.
Here is an example:

03:52:23.511915 IP 1.1.1.1.31586 > 2.2.2.2.80: Flags [S], seq 92802589, win 65535, options [mss 1460,nop,wscale 6,sackOK,TS val ...

Read more : Linux tso (tcp segmentation offload) - what it means and how to enable/disable it | Views : 30319 | Replies : 0

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 Post subject: DNS reverse lookup in Windows 7 and Linux using - nslookup
PostPosted: Tue Jan 13, 2015 8:31 pm 
In a previous article "Unix reverse dns lookup - using dig command" http://forum.ivorde.com/unix-reverse-dns-lookup-using-dig-command-ptr-dns-record-type-t19521.html - some of the most used dns record types and it focused on dns reverse lookups - PTR records - that return a human readable fqdn for an ip address.

Below are few examples of dns reverse lookups using "nslookup" tool available in both Linux and Windows.

First using oneline nslookup command:

C:\Users\Andrei>nslookup -querytype=ptr 8.8.8.8
Server: UnKnown
Address: 172.16.20.2

Non-authoritative answer: ...

Read more : DNS reverse lookup in Windows 7 and Linux using - nslookup | Views : 3013 | Replies : 0

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 Post subject: Fatal error: Trying to set unexisting parameter 'gmysql-host' - PowerDNS error on Debian
PostPosted: Tue Jan 13, 2015 12:03 pm 
Fatal error: Trying to set unexisting parameter 'gmysql-host' - PowerDNS error on Debian

Following error is sent to /var/log/daemon.log on debian when PowerDNS is installed with mysql backend:
Code:
Jan 13 10:59:00 pdnsserver pdns[4873]: Fatal error: Trying to set unexisting parameter 'gmysql-host'
Jan 13 10:59:01 pdnsserver pdns[4752]: Our pdns instance exited with code 1
Jan 13 10:59:01 pdnsserver pdns[4752]: Respawning


This is because because of the bindbackend being also present in /etc/powerdns/pdns.d/pdns.simplebind. To solve this ...

Read more : Fatal error: Trying to set unexisting parameter 'gmysql-host' - PowerDNS error on Debian | Views : 4234 | Replies : 0

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 Post subject: Unix reverse dns lookup - using dig command - PTR dns record type
PostPosted: Mon Jan 12, 2015 5:43 pm 
DIG is a unix dns lookup utility available in most of the distributions, Linux and FreeBSD included. Either in the package distributions or in the base systems.

For a list of dns records, best source is wiki "List of DNS record types" http://en.wikipedia.org/wiki/List_of_DNS_record_types. The main and most used DNS record types are:
- dns SOA record: it defines the start of authority for specific domain.
- dns A record: it points a human readable domain ...

Read more : Unix reverse dns lookup - using dig command - PTR dns record type | Views : 10083 | Replies : 1

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 Post subject: How to dump kernel route cache in Linux
PostPosted: Mon Jan 12, 2015 11:26 am 
How to dump kernel route cache in Linux

Linux kernel, as all kernels operates one or more routing tables to find the next hop to a specific destination.
Once it has found one, it keeps a cache entry remembering the MSS for that specific destinations.

There are two ways to dump linux kernel route cache: "route" and iproute2 "ip" command.


"man route" quote:
Quote:
-C operate on the kernel's routing cache.
-n show numerical addresses ...

Read more : How to dump kernel route cache in Linux | Views : 1901 | Replies : 0

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 Post subject: FreeBSD and Linux: How to find live hosts on a directly connected subnet with ping
PostPosted: Mon Jan 12, 2015 9:24 am 
How to find mac address of all hosts in a connected subnet using "ping" / how to find live hosts on a directly connected subnet

Some systems do not have advanced tools for network scanning discovery like nmap, just the basic "ping". Under FreeBSD and Linux a ping while loop can be used to send requests to all hosts in a specific subnet and then to check the arp table entries:

To acomplish this ping ...

Read more : FreeBSD and Linux: How to find live hosts on a directly connected subnet with ping | Views : 1249 | Replies : 0

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


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