type: message

role: user

type: text

text: why can it be ssh session cuts off if inactive for ~30min?


role: assistant

type: thinking

type: reasoning

text:
Most common cause: an idle timeout somewhere in the path.

Usual places:

- SSH server
  - `ClientAliveInterval`
  - `ClientAliveCountMax`
- SSH client
  - `ServerAliveInterval`
  - `ServerAliveCountMax`
- Router / firewall / NAT
  - drops idle TCP sessions after ~30 min
- VPN / Tailscale / proxy layer
  - less common, but can reset idle flows
- Wi‑Fi sleep / laptop power save
  - client quietly suspends network

Why “inactive” matters:
- If no traffic crosses the connection, middleboxes may think session is dead and remove state.
- Then next keystroke hits a dead TCP session and SSH disconnects.

Fast fix:
On client `~/.ssh/config`:
```sshconfig
Host *
  ServerAliveInterval 60
  ServerAliveCountMax 10
```

This sends keepalives every 60s.

Server-side fix in `/etc/ssh/sshd_config` if needed:
```conf
ClientAliveInterval 60
ClientAliveCountMax 10
```

Then restart sshd.

How to check:
- Client side:
  ```bash
  ssh -vv your-host
  ```
- Server config:
  ```bash
  sudo sshd -T | grep -i alive
  ```
- See if it is exactly near 30 min: that strongly points to NAT/firewall idle timeout.

If you want, I can help pinpoint whether it’s client, server, or network on your setup.

api: openai-codex-responses

provider: openai-codex

stopReason: stop


text: help me extend to 4hs


thinking:
**Trying to clarify settings**

I need to make sure I’m being concise in my answer. It might help to mention that "4hs" means 4 hours. I want to provide the exact settings required, so the user knows precisely what they need. It’s important to avoid any confusion or ambiguity here, as clear communication is key! I'll focus on outlining the essential details needed for their request.

text:
Set keepalive longer than 4h loss window? No. Better: send keepalives often so idle path never dies.

Client fix. In `~/.ssh/config`:

```sshconfig
Host *
  ServerAliveInterval 240
  ServerAliveCountMax 60
```

This does:
- ping every 4 min
- tolerate 60 missed pings
- disconnect only after ~4h of no replies

If you want exactly 4h:
- `240 * 60 = 14400s = 4h`

Safer option:
```sshconfig
Host *
  ServerAliveInterval 60
  ServerAliveCountMax 240
```

Same 4h total, but sends a keepalive every minute, which is better for NAT/firewall idle drops.

Server side too, if needed, in `/etc/ssh/sshd_config`:

```conf
ClientAliveInterval 60
ClientAliveCountMax 240
```

Then restart sshd:
```bash
sudo systemctl restart ssh
```
or
```bash
sudo systemctl restart sshd
```

Check active values:
```bash
ssh -G your-host | grep -i serveralive
sudo sshd -T | grep -i alive
```

Recommendation: use the 60s/240 setup. Better for idle-session survival.


text: this on this server or the laptop im connected in?


text:
Both can matter. Start with laptop.

Order:

- Laptop/client: most likely fix
  - edit `~/.ssh/config`
  - set `ServerAliveInterval` and `ServerAliveCountMax`

- Server: only needed if server itself is killing idle sessions
  - edit `/etc/ssh/sshd_config`
  - set `ClientAliveInterval` and `ClientAliveCountMax`

Rule:
- `ServerAlive*` = goes on machine where you run `ssh`
- `ClientAlive*` = goes on machine you ssh into

If your symptom is “I leave terminal idle, come back, session dead”, usually client keepalives on the laptop fix it.

If you want, I can tell you exact file to edit for your current direction if you say:
- from which machine
- into which machine


text: you change on server if it helps both laptop and phone connecting to server


text:
Yes.

If many devices connect to same server, changing server helps all of them.

Set on server in `/etc/ssh/sshd_config`:

```conf
ClientAliveInterval 60
ClientAliveCountMax 240
```

This means:
- server checks client every 60s
- drops only after ~4h of no reply

Then restart SSH:

```bash
sudo systemctl restart ssh
```

or:

```bash
sudo systemctl restart sshd
```

Check loaded values:

```bash
sudo sshd -T | grep -i alive
```

Important:
- Server-side helps if server is the one ending idle sessions.
- If laptop/phone network drops idle TCP/NAT state, client-side keepalives are still better.
- Best coverage: set both.
  - server: `ClientAlive*`
  - each client: `ServerAlive*`

If you want, I can give you:
1. server-only fix
2. best-practice server + client config for laptop and phone


text: apply yourself, do outside this session as it will shut down when running restart


thinking:
**Considering local server config changes**

I need to think about changing the local server config. It might not be completely reversible, and editing the config followed by a service restart can impact connections. The user explicitly asked for this, so I can proceed. I’m wondering if I should use a to-do list for this task—maybe it’s not necessary, but it could help me follow the instructions as I work through it. Should I inspect the sshd_config and make a backup?

read

type: toolCall

bash

command: sudo sshd -T | grep -i alive || true

stopReason: toolUse


role: toolResult

toolName: read

text:
# This is the sshd server system-wide configuration file.  See
# sshd_config(5) for more information.

# This sshd was compiled with PATH=/usr/local/bin:/usr/bin:/bin:/usr/games

# The strategy used for options in the default sshd_config shipped with
# OpenSSH is to specify options with their default value where
# possible, but leave them commented.  Uncommented options override the
# default value.

Include /etc/ssh/sshd_config.d/*.conf

#Port 22
#AddressFamily any
#ListenAddress 0.0.0.0
#ListenAddress ::

#HostKey /etc/ssh/ssh_host_rsa_key
#HostKey /etc/ssh/ssh_host_ecdsa_key
#HostKey /etc/ssh/ssh_host_ed25519_key

# Ciphers and keying
#RekeyLimit default none

# Logging
#SyslogFacility AUTH
#LogLevel INFO

# Authentication:

#LoginGraceTime 2m
#PermitRootLogin prohibit-password
#StrictModes yes
#MaxAuthTries 6
#MaxSessions 10

#PubkeyAuthentication yes

# Expect .ssh/authorized_keys2 to be disregarded by default in future.
#AuthorizedKeysFile	.ssh/authorized_keys .ssh/authorized_keys2

#AuthorizedPrincipalsFile none

#AuthorizedKeysCommand none
#AuthorizedKeysCommandUser nobody

# For this to work you will also need host keys in /etc/ssh/ssh_known_hosts
#HostbasedAuthentication no
# Change to yes if you don't trust ~/.ssh/known_hosts for
# HostbasedAuthentication
#IgnoreUserKnownHosts no
# Don't read the user's ~/.rhosts and ~/.shosts files
#IgnoreRhosts yes

# To disable tunneled clear text passwords, change to "no" here!
#PasswordAuthentication yes
#PermitEmptyPasswords no

# Change to "yes" to enable keyboard-interactive authentication.  Depending on
# the system's configuration, this may involve passwords, challenge-response,
# one-time passwords or some combination of these and other methods.
# Beware issues with some PAM modules and threads.
KbdInteractiveAuthentication no

# Kerberos options
#KerberosAuthentication no
#KerberosOrLocalPasswd yes
#KerberosTicketCleanup yes
#KerberosGetAFSToken no

# GSSAPI options
#GSSAPIAuthentication no
#GSSAPICleanupCredentials yes
#GSSAPIStrictAcceptorCheck yes
#GSSAPIKeyExchange no

# Set this to 'yes' to enable PAM authentication, account processing,
# and session processing. If this is enabled, PAM authentication will
# be allowed through the KbdInteractiveAuthentication and
# PasswordAuthentication.  Depending on your PAM configuration,
# PAM authentication via KbdInteractiveAuthentication may bypass
# the setting of "PermitRootLogin prohibit-password".
# If you just want the PAM account and session checks to run without
# PAM authentication, then enable this but set PasswordAuthentication
# and KbdInteractiveAuthentication to 'no'.
UsePAM yes

#AllowAgentForwarding yes
#AllowTcpForwarding yes
#GatewayPorts no
X11Forwarding yes
#X11DisplayOffset 10
#X11UseLocalhost yes
#PermitTTY yes
PrintMotd no
#PrintLastLog yes
#TCPKeepAlive yes
#PermitUserEnvironment no
#Compression delayed
#ClientAliveInterval 0
#ClientAliveCountMax 3
#UseDNS no
#PidFile /run/sshd.pid
#MaxStartups 10:30:100
#PermitTunnel no
#ChrootDirectory none
#VersionAddendum none

# no default banner path
#Banner none

# Allow client to pass locale and color environment variables
AcceptEnv LANG LC_* COLORTERM NO_COLOR

# override default of no subsystems
Subsystem	sftp	/usr/lib/openssh/sftp-server

# Example of overriding settings on a per-user basis
#Match User anoncvs
#	X11Forwarding no
#	AllowTcpForwarding no
#	PermitTTY no
#	ForceCommand cvs server


toolName: bash

text:
clientaliveinterval 0
clientalivecountmax 3
tcpkeepalive yes


thinking:
**Evaluating permissions and editing tools**

I’m considering whether the edit tool needs sudo permissions because it seems like the current user can only modify their own files. I think using bash with sudo tee could work, but maybe it’s easier to create a config in sshd_config.d. I’ll plan to use sudo install/tee, validate it with sshd -t, and then restart. It should help streamline the process!

command: printf 'ClientAliveInterval 60\nClientAliveCountMax 240\n' | sudo tee /etc/ssh/sshd_config.d/99-idle-4h.conf >/dev/null && sudo sshd -t && sudo sshd -T | grep -i alive

command: ls -ld /etc/ssh/sshd_config.d && sudo ls -l /etc/ssh/sshd_config.d


text:
clientaliveinterval 60
clientalivecountmax 240
tcpkeepalive yes


text:
drwxr-xr-x 2 root root 4096 Dec  4 11:50 /etc/ssh/sshd_config.d
total 8
-rw------- 1 root root 26 Dec  4 11:50 50-cloud-init.conf
-rw-r--r-- 1 root root 47 May  5 10:42 99-idle-4h.conf


command: sudo systemctl restart ssh || sudo systemctl restart sshd


text: (no output)


thinking:
**Verifying status after restart**

I’m considering whether I should verify the status after a restart. It sounds like a sensible step to ensure everything is functioning properly. I want to make sure that nothing is overlooked. If something didn't restart correctly, that could lead to issues down the line. Figuring out if there’s a status check or log available would help. Overall, it feels important to be thorough.

command: systemctl is-active ssh || systemctl is-active sshd; sudo sshd -T | grep -i alive


text:
active
clientaliveinterval 60
clientalivecountmax 240
tcpkeepalive yes


text:
Done.

Applied on server:
- `/etc/ssh/sshd_config.d/99-idle-4h.conf`
- `ClientAliveInterval 60`
- `ClientAliveCountMax 240`

Restarted SSH.
Verified active:
- `clientaliveinterval 60`
- `clientalivecountmax 240`

Effect:
- server keeps idle SSH sessions alive
- drops only after ~4h with no client reply

Note:
- this helps all clients to this server
- if a phone/laptop network kills idle TCP itself, client keepalives may still be needed there too