Putty ssh session timeout2/29/2024 I know I'm missing something, but what? I also know I have a decade of catching up to do so please bear with this old man. I feel like Scotty from the ST:TNG episode Relics. Not surprising since hackers get more creative all the time and network security needs to evolve. I understand FreeBSD has gotten much more security intense since I last majorly deployed it almost a decade ago. I wouldn't be surprised if PuTTY and Tera Term Pro SSH are outdated and no longer recommended for net and sys admin. I'm also open to someone who has a better recommendation for ssh clients. It gives me a snap shot of the server's health. I would like to have my laptop stay logged in running a top -s1 which is what I do as a habit to monitor a server. What do I need to change in what files to keep an indefinite session alive with PuTTY or Tera Term Pro SSH. The head of the server (keyboard, monitor and pointing device) do not disconnect, but my ssh sessions within the same secure LAN do. When I'm logged into my laptop at home in the same LAN behind the firewall, I want to be able to keep an active ssh console going at all times. Now I'm at FreeBSD 13.1 and I'm scratching my head going through man pages and the handbook and can't find the simple answer on how to disable sshd from timing out. The SSH-1 protocol, incidentally, has even weaker integrity protection than SSH-2 without rekeys.It's been awhile since I assembled a maintained a FreeBSD data center (fall 2012) back in the FreeBSD 8.x days when I was forced into a disability retirement from my IT career. Unlike time-based rekeys, data-based rekeys won't occur when the SSH connection is idle, so they shouldn't cause the same problems. The integrity, and to a lesser extent, confidentiality of the SSH-2 protocol depend in part on rekeys occurring before a 32-bit packet sequence number wraps around. ‘ 1G’ specifies 1 gigabyte (1024 megabytes).ĭisabling data-based rekeys entirely is a bad idea. ‘ 1M’ specifies 1 megabyte (1024 kilobytes). The SSH-2 protocol specification recommends a limit of at most 1 gigabyte.Īs well as specifying a value in bytes, the following shorthand can be used: If this is set to zero, PuTTY will not rekey due to transferred data. I’m not bothering to go into the details of that here. ‘Max data before rekey’ specifies the amount of data (in bytes) that is permitted to flow in either direction before a rekey is initiated. Step 1: Create A Session Profile Create a PuTTY session profile like you normally would. (Except that rekeys have cryptographic value in themselves, so you should bear that in mind when deciding whether to turn them off.) Note, however, the the SSH server can still initiate rekeys. See section 4.13.1 for more discussion of these issues for these purposes, rekeys have much the same properties as keepalives. This has worked reliably for me for several months. If you anticipate suffering a network dropout of several hours in the middle of an SSH connection, but were not actually planning to send data down that connection during those hours, then an attempted rekey in the middle of the dropout will probably cause the connection to be abandoned, whereas if rekeys are disabled then the connection should in principle survive (in the absence of interfering firewalls). To start and enable the SSH Tunnel service: foousernas: sudo systemctl daemon-reload foousernas: sudo systemctl start rvice foousernas: sudo systemctl enable rvice. You might have a need to disable time-based rekeys completely for the same reasons that keepalives aren't always helpful. The SSH-2 protocol specification recommends a timeout of at most 60 minutes. If this is set to zero, PuTTY will not rekey due to elapsed time. ‘Max minutes before rekey’ specifies the amount of time that is allowed to elapse before a rekey is initiated. You can also force a key exchange at any time from the Special Commands menu (see section 3.1.3.2). These options control how often PuTTY will initiate a repeat key exchange (‘rekey’). (The occurrence of repeat key exchange is noted in the Event Log see section 3.1.3.1.) Usually the same algorithm is used as at the start of the connection, with a similar overhead. While this renegotiation is taking place, no data can pass through the SSH connection, so it may appear to ‘freeze’. Therefore, the SSH-2 protocol specifies that a new key exchange should take place every so often this can be initiated by either the client or the server. If the session key negotiated at connection startup is used too much or for too long, it may become feasible to mount attacks against the SSH connection. Previous page next page 4.19.2 Repeat key exchange
0 Comments
Leave a Reply.AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |