Linux Networking refers to any networking function performed by a server running Linux. A Linux server operating as a router or firewall are the most common applications.

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Bulk update BIND zone file from CSV [on hold]

I had to do a mass update of dns records in our bind (on debian lenny). I have no room for error and in my experience i know that bind is very sensitive syntax. I specify you : i have no backup of the ...
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1answer
24 views

Inconsistent nmap scan results

I'm working on a program that depends on scanning the local network for all connected devices and getting their MAC address. To do this, I'm running the following command: nmap -sn 10.0.0.* This ...
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1answer
543 views

Siege: descriptor table full sock.c:119: Too many open files

I am trying to make a stress test in my own server using siege with the following command: $ siege -c 500 myweb.com/somefile.php But I get this error: [error] descriptor table full sock.c:119: Too ...
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0answers
23 views

transparent squid 3.5 + pf on freebsd 10.1

I'm having trouble with pf rule redirect http traffic to squid version 3.5.4 on FreeBSD 10.1. I set up squid like a transparent proxy, now I have pf and I want redirect every http connect to squid but ...
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0answers
23 views

OpenSuse: How to allow an outside network to access the local network?

I want to connect vlans of two separated networks I administer and it's almost complete, Allow me to describe the situation: Network A's firewall is a FortiGate 1000C and the vlan is 192.168.2.0/24 ...
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3answers
75 views

how to monitor network traffic in small office [on hold]

We have a small office with around 30 systems . We have an internet connection connected to a router , The router is connected to a gigabit switch . All the computers are connected to that switch. ...
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2answers
12 views

Modsecurity rule to not scan URIs

Good Morning, I am currently on creating a new mod security 2.5 rule. My deployment: I have an Apache server in reverse proxy mode. This Apache server does not host the websites. Instead, I proxy ...
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0answers
19 views

iptables, redirecting all ingoing connexion

I have this iptables conf on my linux mint... What does it mean ? Chain INPUT (policy ACCEPT) target prot opt source destination ACCEPT all -- 13.37.42.0/24 ...
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1answer
2k views

Error while bringing up eth1

I'm getting this error while bringing up my network card: (process:2550): WARNING **: _nm_object_get_property: Error getting 'State' for /org/freedesktop/NetworkManager/ActiveConnection/3: (19) ...
4
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0answers
51 views

How to troubleshoot rx_missed_errors?

Migrating from old server to new one, after setting all services, I notice a big dropped rx packets in my NIC: $ ifconfig eth2 | grep 'RX.*drop' RX packets:2059646370 errors:0 ...
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1answer
67 views

vyatta virtual router interface aliasing does not work

I am trying to create an alias on vyatta virtual router. But I do not seem to get it to work. In vyatta we have to just add another address to the interface to add an alias. But the interface is not ...
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0answers
41 views

How to get GPS time in linux from an external server? [closed]

I am building an application in linux which needs GPS time. But I don't have any GPS receiver. How can I get GPS time from an external server?
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0answers
17 views

Spurious retransmission, Dup ACK and HTTP 408

I have a server which serves as sms gateway (using kannel) and have multiple client connecting to it, but recently this one client with their particular IP said that they can't send to my server and ...
0
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0answers
24 views

Restricting ports to application / user

I'm currently working on a platform that will allow other users to run their applications on my platform. Though, we need to be able to restrict this application in terms of RAM, CPU usage, network ...
2
votes
1answer
184 views

How to route traffic through different interfaces based on the port number?

iptables -A PREROUTING -i usb0 -t mangle -p tcp --dport 8080 -j MARK --set-mark 1 iptables -L Chain INPUT (policy ACCEPT) target prot opt source destination Chain ...
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0answers
17 views

Bandwidth Policing on Linux gateway - not QoS

I have a linux server providing NAT to a large subnet (/16) using iptables to-destination + multiple external ip's to survive port exhaustion. I've looked at using tc / htb such as here Limiting ...
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1answer
1k views

WMI: wmic linux agent query error: NTSTATUS: NT_STATUS_ACCESS_DENIED

Myself new to wmic and keep trying for a long time with default agent query approach. wmic is linux based WMI tool to talk to windows WMI agent. While trying to fetch data with wmic from nt(win7 with ...
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1answer
996 views

Network aliases on boot on Fedora 17

We have a fedora server(Fedora release 17 (Beefy Miracle)) with a few aliases on the main NIC that don't get setup during boot. Here's my config: # cat /etc/sysconfig/network-scripts/ifcfg-em1* ...
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1answer
26 views

Time Between successive DNS queries.

Using a PC running Ubuntu 14.04. I'm testing web browsing using a very low speed and low data rate link. My system is congested with DNS queries (and other types of packets like TCP re-transmission). ...
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0answers
19 views

How can I bridge an HTTP server from an interface to another in Linux?

In a Linux server I have an HTTP server that's available at eth1 with ip1, and I want to make it available to the network in eth2 with ip2. How can I do this? Example: I have an http server on ...
0
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1answer
12 views

Troubleshooting Curl Timeouts

I run a SaaS monitoring service. Our standard integration example is to make a curl request to a special URL we provide. We have an intermittent issue where a user is hitting a 10 second curl timeout ...
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4answers
2k views

Mysterious “fragmentation required” rejections from gateway VM

I've been troubleshooting a severe WAN speed issue. I fixed it, but for the benefit of others: Via WireShark, logging, and simplifying the config I narrowed it down to some strange behaviour from a ...
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1answer
34 views

Linux: nslookup and dig resolve $HOSTNAME, but ping doesn't

In our private network we have a Consul service discovery server (10.241.232.14) that provides a DNS interface (port 8600). We would like to set our common DNS servers to forward some queries to the ...
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0answers
18 views

Gateway to internet on CentOS 6

I have 2 CentOS 6 linux servers say hostnames cent001 and cent002 cent001 has 2 Nic's 1 Bridged and 1 Nat cent001 is able to ping google server 8.8.8.8 with the help of bridged NIC cent002 has only ...
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0answers
19 views

dhclient vpn_tun0 causing internet disconnect after upgrade to ubuntu 15.04

A few weeks ago I installed softether vpnclient on my ubuntu 14.04 laptop and vpnserver on an ec2 instance. The server uses softether secureNAT and the softether dhcp server. My client produces an ...
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0answers
18 views

Problems with route table with two nics on different subnets

I have an Ubuntu server with two NICs on two different vlans. Both nics are able to reach the internet. The server is an Ubuntu MAAS machine and therefore has pxe and dhcp and such. The DHCP server ...
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0answers
22 views

Get Original Destination Port From iptables

I would like to create a local server that acts as a proxy for all trafic, but how would I determan the original ports when using iptables to rederect the network traffic. I need this for when the ...
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2answers
49 views

Different subnet mask on router and DHCP server

ran into something funny today and am still scratching my head on why this happened. I was trying to increase the number of ip addresses available from my dhcp server by changing the netmask from /24 ...
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2answers
117 views

How to run Different congestion control algorithms in FEDORA 17?

I need to use different congestion control algorithms for tcp flow. How can I continue using those flow congestion algorithms from Fedora 11 in Fedora 17?
5
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5answers
9k views

Is it dangerous to change the value of /proc/sys/net/ipv4/tcp_tw_reuse?

We have a couple of production systems that were recently converted into virtual machines. There is an application of ours that frequently accesses a MySQL database, and for each query it creates a ...
0
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2answers
58 views

How to get a client IP address from a specific network?

I have a condition to filtering IP address from client, and I just have their IP network like this 1.1.0.0/17. If some client from this network will be filtered as special user on my website. And I ...
2
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1answer
24 views

ModSecurity rule to not scan URI

I am having difficulty creating a new mod security 2.5 rule. My deployment: Apache server, Setup as a reverse proxy. (so the apache webserver __does not_ host the website. Instead, I proxy the ...
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0answers
27 views

Unable to Mount a directory on linux server :- Error ICMP host unreachable - admin prohibited, length 68

Folks , I have two linux server. I want to mount one directory /symantic of one file system to another. I am able to ping , i am able to do telnet from each other. I have checked port 2049 which is ...
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1answer
48 views

Trouble with network (ping, route, gateway)

I have a server running CentOS 7 and I connect to it by ssh. SSH takes a little bit to connect compared to the other server I have setup. This server has 2 ethernet ports (1 motherboard and 1 card). ...
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0answers
17 views

OpenVZ: Node iptables doesn't append rules

I want to make a set of rules on iptables inside of a node, but it seems that the iptables isn't appending all the rules or somehow and kick me out everytime I run the following script (I'm using this ...
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0answers
10 views

VIP (Pacemaker) - Second VIP on host stops responding after random period of time

I've got a host that was recently installed with Pacemaker, 3 physical interfaces, on two of which a VIP has been setup, VIP1 appears to be working flawlessly, while VIP2 becomes unavailable after a ...
2
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1answer
140 views

Mounting encrypted Samba share (linux server/client)

I'm trying to set up encrypted samba access. In order to achieve that I've added 2 lines to [global] scope in smb.conf: server signing = mandatory smb encrypt = mandatory But unfortunately I can't ...
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0answers
10 views

Suse11 default gateway lost after interface restart

Doing some test on a SLES 11 SP2 virtual server I noticed the default route was lost after restarting the related interface: # netstat -rn Kernel IP routing table Destination Gateway ...
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1answer
1k views

How to stop a infinite running process(ztail) started by a ssh session after that session is closed

I have a peculiar problem. My server supports multiple ssh session simultaneously, so that multiple admins can manage it simultaneously. We have a command which calls ztail to show the compressed log ...
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0answers
89 views

SynProxy can not return syn ack packets with asymmetric dual bridge topology

I have a asymmetric dual bridge topology as shown below when i connect from 172.16.11.5 and 172.16.10.6 with ssh but i can not connect because of SynProxy. ------- ...
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0answers
45 views

Fail2Ban / IPTables does not block IPs

My server : Debian Wheezy 7.8, Postfix/Dovecot, Fail2Ban/IPTables I've postfix attacks : /var/log/mail.warn Jun 12 08:03:45 myserver postfix/smtpd[8325]: warning: ...
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2answers
1k views

VMWare and Turnkey Linux appliance can't access network

I have a VMWare ESXi cluster running many Windows and Linux VMs perfectly. I have installed the Turnkey Linux Redmine appliance, and am having a lot of trouble getting the networking to work ...
38
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6answers
4k views

How can you tell what a server actually does? [closed]

I've been handed 3 Linux boxes, 1 front facing with apache on it and another 2 which, as far as I can tell, don't do an awful lot. All running on Redhat. The question is simple: How can I tell what ...
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2answers
20 views

IP from multi gateway, openvz debian

I have a problem with network in my dedicated server. I have a host: ip 188.60.240.71 netmask 255.255.255.128 gateway 188.60.240.1 broadcast 188.60.240.127 network 188.60.240.0 I order additional ...
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1answer
1k views

Infiniband port status UP but can't open UMAD port ((null):0)

My system has 2 infiniband devices, one of which has both the ports up. $> ibstatus Infiniband device 'mlx4_0' port 1 status: default gid: fe80:0000:0000:0000:0002:c903:000f:0a9f ...
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1answer
53 views

How to assign multiple IPv6 Alias addresses to one network interface

I have an IPv6 Range which i am trying to assign on a centos6 server. I have updated my below files for IPv6 configuration: [root@test ~]# cat /etc/sysconfig/network NETWORKING=yes ...
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7answers
17k views

Can't start CentOS 7 “network” service

I Can't start CentOS 7 "network" service after disabling and removing "NetworkManager" service. When I check the network service status, it comes up with the following error: #systemctl status ...
2
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3answers
3k views

How can I achieve OpenVPN client routing without NAT on Linode

I've set up an OpenVPN network, and it is working properly in the sense that I can access the inner/LAN machines from the remote client. However, my problem is that all traffic from the remote ...
0
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1answer
24 views

REDSOCKS goes 'out of file descriptors' when trying to redirect all outgoing (TCP) traffic from my Linux machine

I'm trying to redirect all outgoing TCP traffic from my linux box to the remote SOCKS5 proxy server. Currently I'm using the following rule in the OUTPUT chain: sudo iptables -t nat -A OUTPUT -p tcp ...
1
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1answer
51 views

Difference between “genmask” and “netmask”?

In the output of route -n on Linux, you get something like this: Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 10.0.0.1 ...