A connection generally refers to a TCP/IP connection, that is established as the result of the handshake between 2 hosts.

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56
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5answers
7k views

I accidentaly forbid SSH connection to a remote server… What's next?

Let's say it again, we all make mistakes, and I have just made one. A brief history: I was doing some stuff on a VPS (Debian) I'm renting, when I noticed some strange behaviour. Using the netstat ...
46
votes
4answers
23k views

Why do consoles sometimes hang forever when SSH connection breaks?

I've seen this with so many consoles (on Linux, Mac, ...), and with lots of different machines in many different networks. I can never pinpoint the exact reason, why this happens: All you have to do ...
20
votes
6answers
30k views

How to force MySQL to connect by TCP instead of a Unix socket?

I would like to analyze mysql traffic. Right now, all mysql requests are sent to the MySQL unix socket: unix 2 [ ACC ] STREAM LISTENING 3734388 15304/mysqld ...
17
votes
7answers
59k views

ssh tunnel refusing connections with “channel 2: open failed”

All of a sudden (read: without changing any parameters) my netbsd virtualmachine started acting oddly. The symptoms concern ssh tunneling. From my laptop I launch: $ ssh -L 7000:localhost:7000 ...
10
votes
3answers
19k views

Understanding this error: apr_socket_recv: Connection reset by peer (104)

So, if I do some benchmarking with apache benchmark (ab), and I use large numbers of requests. Then sometimes in the middle of a test I get this error. I don't even know what it means. So how can I ...
9
votes
1answer
6k views

Remote connection to MySQL server takes very long

I have a MySQL 5.0.75 server running on my Linux notebook to which I want to connect from another machine in the local network. This connection takes 5-6 seconds: mysql -h 172.22.65.101 -u myuser ...
9
votes
6answers
66k views

SQL - an error occurred during the pre-login handshake

Until yesterday evening, I was able to connect to my server from my local machine. Now, I get the following error: A connection was successfully established with the server, but then an error ...
9
votes
3answers
114 views

Log connections to program

Besides for using iptables to log incoming connections.. Is there a way to log established inbound connections to a service that you don't have the source to (suppose the service doesn't log stuff ...
9
votes
2answers
6k views

Connection error to mysql database

My application needs to do quite frequent connects to a mysql database on another machine. However I get frequent errors on connection; I can usually eventually connect but after many retries. The ...
8
votes
2answers
33k views

How do I allow outgoing connections via iptables?

I have two servers. The program on the first needs to communicate with the second on port 2194. I know its not working, because when I do: root@server1 [~]# telnet myserver2.com 2194 Trying ...
8
votes
2answers
3k views

Finding short-lived TCP connections owner process

Running tcpdump on local connections to an apache server, I found TCP connections being established and closed immediately every 2 seconds. How do I find which process is responsible for these? ...
8
votes
3answers
2k views

Can I make TCP/IP session to run less than 60 seconds?

Our server is overloaded with TCP/IP sessions, we have 1200 - 1500 of them. Most of them are hanging in TIME_OUT state. It turns out that a connection in TIME_OUT state occupies a socket until 60 ...
8
votes
1answer
2k views

PHP/mySQL: how to debug a 'too many connections' error?

I am working right now with PHP website on my client's dedicated server and I get periodically an error too many connections but ~5 users are browsing this page. In phpMyAdmin I can see that max ...
7
votes
2answers
8k views

Impact of Connection Close vs Keep-alive

I'm configuring our servers, and due to the nature of our load balancer, we can't send connection keep-alive headers. I'm trying to determine the impact of sending these headers to both the end-user ...
7
votes
2answers
5k views

Certificates in SQL Server 2008

I need to implement SSL for transmissions between my application and Sql Server 2008. I am using Windows 7, Sql Server 2008, Sql Server Management Studio, and my application is written in c#. I was ...
6
votes
1answer
1k views

Redis connection issue

We are currently experiencing a lot of Redis errors with the message Unable to connect: read error on connection, trying next server We run Redis on FreeBSD using PHP Redis and we have a hard ...
6
votes
1answer
1k views

https lingering TIME_WAIT connections

From my client PC I'm connecting to a webserver, it uses HTTPS only. When I connect I see in TCPView (sysinternals tool alternative to netstat) a lot of TIME_WAIT connections to the https endpoint. ...
6
votes
1answer
3k views

Load balancing MySQL using HAProxy: Got an error reading communication packets?

I've set up load balancing MySQL slaves using HAProxy via a xinetd. 2 load balancers shared a virtual IP that is managed by Pacemaker: crm configure show: node SVR120-27148.localdomain node ...
6
votes
4answers
5k views

apache webserver unresponsive with server-status showing all child processes waiting for connection

My setup: i have 3 nearly identical webserver machines serving the same high loaded dynamic website with simple load balancing over dns. The service has been working for over two years with the same ...
5
votes
6answers
3k views

How can I find the total number of TCP connections for a given port and period of time by IP?

On a Linux system there are plenty of methods for listing the current TCP connections for a given port by connecting IP but: how can I count the total number of connections to a port per source IP for ...
5
votes
4answers
3k views

mysql connection is slow (5seconds)

After building my webapp on a first boot i create 2 connections to mysql on debian then 1-2 (r/w) for every page after that. The connection consistently take 5.2 seconds to connect. Debian is in a VM ...
5
votes
2answers
200 views

Effects of internet connection speeds on server queries

Can my internet connection significantly effect queries run on phpmyadmin? I am currently 18 down and 30 up. I switched internet connections today and noticed a deep drop in query performance. The ...
5
votes
4answers
2k views

How to wire 20 computers and 20 phones and 1 server into LAN?

I have currently 3 switches Two Netgear JFS524 with 24 slots, One Belkin with 16 slots. Server DSL Internet Router. Main question is how to connect switches together, two Netgear's are next to each ...
5
votes
2answers
22k views

What is the typical maximum number of database connections for Oracle running on Windows server?

We are maintaining a database server that serve a large number of clients. Each client typically running serveral client-applications. The total number of connections to the database server (Oracle ...
5
votes
1answer
248 views

Odd TCP termination sequence

While troubleshooting another thing, I've noticed an odd pattern of TCP closes. Packets: http://www.cloudshark.org/captures/7590ec4e6bef What's happening is that the last few packets of the close ...
5
votes
1answer
852 views

Should the database connection limit equal the number of processes connecting?

I noticed that PostgreSQL and MySQL have a 100 client connection limit by default. I'm wondering if I should turn this down since the webserver is on the same box and I only have about 20 PHP ...
5
votes
1answer
278 views

Connecting to AS/400 hardware

In about 2-3 weeks I'm getting an old AS/400 server (something 9406, probably 6xx or 8xx) to learn OS/400 from administrators point of view. Will I need some special hardware to connect and do IPL ...
5
votes
1answer
5k views

Can't connect to MySql server on remote server

Connecting to: CentOS v?? with MySql 4.?? in Nashville (example public ip=11.11.11.11) Stack: Cable modem as gateway > router with forwarding > CentOs Box Connecting from: Windows 2003 R2 in ...
5
votes
2answers
3k 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 ...
4
votes
8answers
2k views

What's better than wifi to connect servers wirelessly (ethernet-like latency)?

I need to connect some servers wirelessly and would like to know what other technologies (than Wifi) exist to get an idea of the possibilities. It would nice to know the pros/cons, limitations. ...
4
votes
2answers
287 views

Linux box takes 10 seconds to make a connection

My machine is taking 10 seconds to establish a connection. Once the connection is established, it is up to speed and works correctly. But if I for example ping www.google.com, it takes 5 seconds for ...
4
votes
6answers
974 views

What causes a delay of 100 ms in initiating an HTTP connection?

Settings: this is a quad CPU machine, plenty strong, not loaded at all (neither CPU nor network), the client is a Windows Server 2008 64bit, the server is a linux box. I have four threads that are ...
4
votes
3answers
10k views

Network packet size on sql server connection string to improve throughput

We have a dataload job that moves a relatively large amount of data across the network between two sql servers. the servers are on the same subnet and there is only a switch between them. the data ...
4
votes
1answer
135 views

Can a TIME_WAIT connection be restored?

Is it possible to restore a connection that is in state TIME_WAIT? If not, I use raw packets (forgering the source), is it possible? (Please understand that I do not intend to do bad things, it's ...
4
votes
1answer
2k views

Why are connections in FIN_WAIT2 state not closed by the Linux kernel?

I have an issue in a long-lived process called kube-proxy being part of Kubernetes. The problem is that from time to time a connection is left in FIN_WAIT2 state. $ sudo netstat -tpn | grep ...
4
votes
2answers
2k views

Too many active IP Connections

I have a Linksys WRT54GS v7 with a dd-wrt (micro) installed on. When I try to view Active IP Connections, I see too many connection there. Interestingly, there are about 120 connections that originate ...
4
votes
1answer
2k views

Unable to connect to a remote database

I'm playing with MongoDB. I have a good deal of experience with MySQL and was using something called Sequel Pro to connect to remote databases. I'm now trying MongoHub but can't seem to get it to ...
4
votes
1answer
750 views

BGINFO with MySQL for storing computer information

We are trying to set up BGinfo to record network computers' information in a centralized database. We intend to set up BGinfo to start up for all users and record logon and logoff time plus setting up ...
4
votes
1answer
2k views

Is it possible to see active connections in nginx?

Is it possible to see what URLs are actively being served by nginx (i.e., see the URLs that are in the middle of being responded to, not the ones that nginx has finished responding to). I would like ...
4
votes
1answer
1k views

IPtables rate-limit, What are the differences between modules? Recent, Limit

I am doing some rate-limiting with IPtables, and i'm not sure if I should use "Recent" or "Limit" What are the differences between the two? If they both achieve the same result, which one has ...
4
votes
3answers
2k views

Intermittent MySQL connection errors

I have been recently getting these errors on my server: mysql_connect() [function.mysql-connect ]: Can't connect to MySQL server on 'xxx.xxx.xxx.xxx' (4) I don't think this is a credentials ...
4
votes
1answer
1k views

connection sync suggestions with HAproxy and keepalived

I managed to get HAproxy working in a failover configuration as suggested on the architecture.txt document using keepalived. I used CentOS 5.5, HAproxy rpm (haproxy-1.3.25-1.el5) from epel repo, and ...
4
votes
2answers
278 views

What permission is needed for my SQL Server 2005 DB for a WebUser?

I have a connection string in my asp.net code that looks at a SQL Server 2005 database. I created a UserName called WebUser and granted him db_datawriter and db_datareader in SQL Server 2005. Both ...
4
votes
0answers
580 views

TCP connection stuck in SYN_RECV state despite ACK received

My client and server are both internal machines. tcpdump on both client and server show all three parts of handshake are communicated, however netstat on server shows SYN_RECV, and on client shows ...
4
votes
1answer
858 views

Unix socket connection limit

This may appear like an already discussed/answered question. But I am specifically looking for info which I couldn't find anywhere answered clearly. I have an Nginx + php-fpm setup which uses unix ...
4
votes
1answer
10k views

PPTP connection fails with errors 800/806

I've got a client (Server 2008 R2) that won't connect to our production environment PPTP VPN server (Server 2003, running RRAS). The server is behind a firewall that has TCP1723 open as well as GRE. ...
3
votes
3answers
2k views

“ssh root@server” hangs forever

Sometimes my ssh client will take forever to login. This happens when the server is not responding (overloaded, killed processed, ...). My automated scripts will then fail because the ssh process ...
3
votes
1answer
2k views

Wireless Access Point connection benefits over Wireless Routers

While I was doing research on wireless connection limits, I stumbled upon this question. Zypher's answer seems to suggest connection capacity benefits of wireless access points over wireless routers. ...
3
votes
2answers
568 views

SSH Connection Lost

I have recently started using iptables, and I executed iptables -F without knowledge of what it might do. And suddenly I have lost connection to the node. I can't even ping the node. Any help would be ...
3
votes
2answers
16k views

Increasing of max (more than 10) TCP Connections

I have the following problem on one of my servers: On other servers max TCP Connections is dynamical and much more higher than 10. How to increase max TCP Connections in this server in Windows ...