Putty command line options keep alive
I am trying to code a shell-script that uses a ssh-connection for doing "heartbeats". I want to terminate the client- and server-side of that connection after a certain timeout after the connection drops. You probably want to use the ServerAlive settings for this.
They do not require any configuration on the server, and can be set on the command line if you wish. This will send a ssh keepalive message every 5 seconds, and if it comes time to send another keepalive, but a response to the last one wasn't received, then the connection is terminated. The critical difference between ServerAliveInterval and TCPKeepAlive is the layer they operate at. The TCPKeepAlive option is actually a very different method of keeping connections alive from ClientAlive-like or ServerAlive-like options.
Are per BSD SSH manual pagewe can read that:.
The client alive messages are sent through the encrypted channel and therefore will not be spoofable. The TCP keepalive option enabled by TCPKeepAlive is spoofable. The client alive mechanism is valuable when the client or server depend on knowing when a connection has become inactive.
The TCPKeepAlive make sure whether the system should send TCP keepalive messages to the other side. The default option is always enabled.
If you're using ClientAliveIntervalyou can disable TCPKeepAlive. This option will send a message through the encrypted channel to request a response from the client the default is 0, so no messages are sent to the client and ClientAliveCountMax sets the number of client alive messages before sshd will disconnect the client, by terminating the session.
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How does tcp-keepalive work in ssh?
ssh - How to make putty to not break my session after some time? - Unix & Linux Stack Exchange
What I found so far: Target operating system is SLES11 SP2 - but I do not think that is relevant here. Nils 11k 6 29 Those united states stock market wikipedia are all meant for situations where a firewall or intermediary device along the connection will terminate the connection.
Those parameters are for sending periodic data to keep the connection alive, and also for shutting the connection down when there make money from pub quizzes X outstanding replies. Can you provide a little more detail of what youre doing? Are you using the ControlMaster putty command line options keep alive and using slave connections? I just want to build a means to determine, if another node is "down" using several ssh-network connections with several physical lines.
I do this by just openening an ssh-session that more or less does an endless loop. I want that session to terminate if the connections breaks. TCPKeepAlive operates on the TCP layer. It sends an empty TCP ACK packet. Firewalls can be configured to ignore these packets, so if you go through a firewall that drops idle connections, these may not keep the connection alive.
ServerAliveInterval operates on the ssh layer. It will actually send data through ssh, so the TCP packet has encrypted data in and a firewall can't tell if its a keepalive, or a legitimate packet, so these work better.
I guss that TCPKeepalive simply uses the TCP-stack-defaults - so it is harder to configure, too. This also solves the ghost-user problem. I believe this can also be done in PuTTY settingschanging Seconds between keepalives to under Settings Connection. Are per BSD SSH manual pagewe can read that: Sign up or log in StackExchange. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name.
Nth Design ยป Using KeepAlive in PuTTY
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How does tcp-keepalive work in ssh? - Unix & Linux Stack Exchange
This site is not affiliated with Linus Torvalds or The Open Group in any way. I think this is the right direction. MathOverflow Mathematics Cross Validated stats Theoretical Computer Science Physics Chemistry Biology Computer Science Philosophy more 3. Meta Stack Exchange Stack Apps Area 51 Stack Overflow Talent.