jm + nat   9

Push notifications delayed, Hearbeat Interval not reliable - Google Product Forums
Good thread on GCM notifications and their interactions with NAT -- they are delivered over a single TCP connection to port 5228 to the google servers, kept alive, and NAT timeouts can hang the conn resulting in delayed notifications.

Particularly useful is the *#*#426#*#* dial code, which displays a log screen on Android devices with GCM debugging info.
android  gcm  google  push-notifications  nat  tcp 
june 2016 by jm
About to leave UPC due to (lack of) port forwarding - Boards.ie
Virgin Media/UPC seem to have silently deployed an IPv6 "carrier-grade NAT" setup called "DS-Lite" -- ie. all customers now get just a routable IPv6 address, and share a small pool of IPv4 NATs. This breaks a multitude of useful services, including UDP IPSec VPNs it seems
udp  vpns  isps  virgin-media  virgin  ireland  ds-lite  ipv6  tunnelling  networking  nat  ipv4 
may 2016 by jm
good example of Application-Level Keepalive beating SO_KEEPALIVE
we have now about 100 salt-minions which are installed in remote areas with 3G and satellite connections.

We loose connectivity with all of those minions in about 1-2 days after installation, with test.ping reporting "minion did not return". The state was each time that the minions saw an ESTABLISHED TCP connection, while on the salt-master there were no connection listed at all. (Yes that is correct). Tighter keepalive settings were tried with no result. (OS is linux) Each time, restarting the salt-minion fixes the problem immediately.

Obviously the connections are transparently proxied someplace, (who knows what happens with those SAT networks) so the whole tcp-keepalive mechanism of 0mq fails.


Also notes in the thread that the default TCP timeout for Azure Load Balancer is 4 minutes: https://azure.microsoft.com/en-us/blog/new-configurable-idle-timeout-for-azure-load-balancer/ . The default Linux TCP keepalive doesn't send until 2 hours after last connection use, and it's a system-wide sysctl (/proc/sys/net/ipv4/tcp_keepalive_time).

Further, http://networkengineering.stackexchange.com/questions/7207/why-bgp-implements-its-own-keepalive-instead-of-using-tcp-keepalive notes "some firewalls filter TCP keepalives".
tcp  keep-alive  keepalive  protocol  timeouts  zeromq  salt  firewalls  nat 
april 2016 by jm
Seesaw: scalable and robust load balancing from Google
After evaluating a number of platforms, including existing open source projects, we were unable to find one that met all of our needs and decided to set about developing a robust and scalable load balancing platform. The requirements were not exactly complex - we needed the ability to handle traffic for unicast and anycast VIPs, perform load balancing with NAT and DSR (also known as DR), and perform adequate health checks against the backends. Above all we wanted a platform that allowed for ease of management, including automated deployment of configuration changes.

One of the two existing platforms was built upon Linux LVS, which provided the necessary load balancing at the network level. This was known to work successfully and we opted to retain this for the new platform. Several design decisions were made early on in the project — the first of these was to use the Go programming language, since it provided an incredibly powerful way to implement concurrency (goroutines and channels), along with easy interprocess communication (net/rpc). The second was to implement a modular multi-process architecture. The third was to simply abort and terminate a process if we ended up in an unknown state, which would ideally allow for failover and/or self-recovery.
seesaw  load-balancers  google  load-balancing  vips  anycast  nat  lbs  go  ops  networking 
january 2016 by jm
VPC NAT gateways : transactional uniqueness at scale
colmmacc introducing the VPC NAT gateway product from AWS, in a guest post on James Hamilton's blog no less!:
you can think of it as a new “even bigger” [NAT] box, but under the hood NAT gateways are different. The connections are managed by a fault-tolerant co-operation of devices in the VPC network fabric. Each new connection is assigned a port in a robust and transactional way, while also being replicated across an extensible set of multiple devices. In other words: the NAT gateway is internally horizontally scalable and resilient.
amazon  ec2  nat  networking  aws  colmmacc 
january 2016 by jm
Dublin-traceroute
uses the techniques invented by the authors of Paris-traceroute to enumerate the paths of ECMP flow-based load balancing, but introduces a new technique for NAT detection.


handy. written by AWS SDE Andrea Barberio!
internet  tracing  traceroute  networking  ecmp  nat  ip 
october 2015 by jm
webrtcH4cKS: ~ coTURN: the open-source multi-tenant TURN/STUN server you were looking for
Last year we interviewed Oleg Moskalenko and presented the rfc5766-turn-server project, which is a free open source and extremely popular implementation of TURN and STURN server. A few months later we even discovered Amazon is using this project to power its Mayday service. Since then, a number of features beyond the original RFC 5766 have been defined at the IETF and a new open-source project was born: the coTURN project.
webrtc  turn  sturn  rfc-5766  push  nat  stun  firewalls  voip  servers  internet 
october 2014 by jm
pwnat - NAT to NAT client-server communication
'a proxy server that works behind a NAT, even when the client is behind a NAT, without any 3rd party'. nifty, by Samy "MySpace worm" Kamkar
samy-kamkar  apps  firewall  ip  nat  networking  pwnat  stun  traversal  tcp  sysadmin  tunneling  udp  from delicious
march 2010 by jm
Mobile Internet access data retention (not!)
so, it seems the wireless ISPs don't have sufficient IPv4 space for their customers, and are filtering access to the internet via NAT; unfortunate side effect is that this breaks data retention as defined in the UK. wonder if the same applies here?
uk  data-retention  privacy  nat  isps  wireless  mobile  phones  networking  internet  filtering  from delicious
january 2010 by jm

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