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4 votes

No SYN-ACK Packet from server

Somes ideas on why sometimes your server doesn't answer with SYN-ACK : Application on the server is stopped when the SYN packet is sent : This can be a crash and then manage to work again with a auto ...
  • 41
3 votes

Early warning of port exhaustion in Linux

you could write a bpf software using bpftrace to watch all connections opening and closing and maintain counters for each client,server,server port combination. That seems to be overly complex for ...
  • 196
3 votes

Redis cannot bind a specific ip address?

As far as I understand, the "bind" is like an "allow connections from this ip"but I might've misunderstood it. You have. The configuration file for redis is fairly self ...
  • 5,244
3 votes

Dovecot claims ports are in use, netstat disagrees

dovecot would appear to not be aware of (compatible with) portreserve. Check /etc/portreserve for configuration files that are reserving ports you need and remove them from scope (e.g. rename them ...
  • 937
2 votes

HAProxy: Defer TCP connection to backend only after first data arrives

Was looking for this myself, found the answer in the the examples of the config reference: https://cbonte.github.io/haproxy-dconv/2.0/configuration.html#4-tcp-request%20content in the frontend: tcp-...
1 vote
Accepted

Is there a way to exclude a network interface from being bound via INADDR_ANY?

Have you tried or considered iptables (I know its hard to specify precisely the requirements, but it is probably worth trying and trying until success ): To allow traffic only from IP address 10.0.0.1 ...
1 vote
Accepted

Which machine is actually closing the TCP socket and why?

What should I do in order to know which machine is actually closing the TCP socket In order to find out which side closes the connection you need to do a packet capture. See https://wiki.wireshark....
1 vote

Client TCP segments arrive in batches

Take a look at RSO and GSO as that will combine segments into larger frames that are then delivered to the kernel. That shouldn't have a 5 second delay, but that may be mis-configured.
1 vote
Accepted

Where does Ubuntu log TCP connections?

Where can I find the logs for these connections, e.g., who initialized the connections and how they are allowed/authorized (if this is the right word)? There isn't really a general answer to this ...
  • 42.5k
1 vote

NGINX is not respecting DNS TTL of Upstream Server

You need to explicitly configure nginx to actively and regularly refresh hostname to IP-address mappings. Otherwise that mapping is only made on restarts /reloads. (That is a shortcoming that happens ...
  • 1,167
1 vote

How to list all the TCP_alloc on a server?

#!/bin/bash for i in /proc/* ; do if [ -d $i/fd ];then echo $i $(ls $i/fd -l | grep socket: |wc -l) fi done To find out all the TCP connections of each process. It's OK now.
  • 111
1 vote

Having Trouble Identifying TCP Congestion Control Provider option: Default

Run in Powershell Get-NetTCPSetting | Select SettingName, CongestionProvider Congestion Provider can only be modified on windows server OS
1 vote
Accepted

Could someone please explain the difference between these expressions

Well, the difference is simple. first rule immediately drops non-HTTP second rule immediately allows HTTP Although it may trick you, these aren't even close. Because: there are several types of ...
  • 8,460
1 vote

haproxy SSL/TLS Passthrough Proxy not working?

Since you pass the connection through to Gmail, the client also gets the Gmail certificate, which obviously is only valid for the Gmail host. The certificate must contain the hostname you are ...
1 vote

localhost loopback tcp connection in Windows: increase the bottleneck of 65535 bytes per segment

A TCP segment is encapsulated by an IP packet which is generally limited to 65,535 bytes (2^16-1) since the Total Length field is 16 bit. That's the end of the ladder for both TCP and IP. If you can't ...
  • 9,162
1 vote

How to debug frequent "connection reset by peer"

I had the same issue when tried to connect to remote host via VPN. I got an error: OpenSSL SSL_connect: Connection reset by peer in connection <HOST>:<PORT> In my case (on Fedora 36) I ...
1 vote

How does server-side `TIME_WAIT` really work?

The client will use a new TCP ISN (initial sequence number) based on an algorithm (incremented by 1 roughly every 4 microseconds), and the ISN is basically always larger than sequence number sent in ...
  • 111
1 vote

Wireshark "length" column - what does it include?

In short, It is the size of the network packet which is mentioned on the packet details pane.
1 vote

Under what circumstances is TCP-over-TCP performing significantly worse than TCP alone (2014)?

Soft-ether VPN is an example of a TCP over TCP implementation. Under normal circumstances and perfect network throughput, the VPN works just fine with acceptable latency. However, with the slightest ...

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