Copy files from a remote server which requires superuser preliveges to local machine [duplicate] - scp

This question already has answers here:
WinSCP connect to Amazon AMI EC2 Instance changing user after login to "root"
(6 answers)
Closed last year.
I am trying to use WinSCP to transfer files over to a Linux Instance from Windows.
I'm using private key for my instance to login to Amazon instance using ec2-user. However ec2-user does not have access to write to the Linux instance
How do I sudo su - to access the root directory and write to the Linux box, using WinSCP or any other file transfer method?
Thanks

I know this is old, but it is actually very possible.
Go to your WinSCP profile (Session > Sites > Site Manager)
Click on Edit > Advanced... > Environment > SFTP
Insert sudo su -c /usr/lib/sftp-server in "SFTP Server" (note this path might be different in your system)
Save and connect
Source
AWS Ubuntu 18.04:

There is an option in WinSCP that does exactly what you are looking for:

AFAIK you can't do that.
What I did at my place of work, is transfer the files to your home (~) folder (or really any folder that you have full permissions in, i.e chmod 777 or variants) via WinSCP, and then SSH to to your linux machine and sudo from there to your destination folder.
Another solution would be to change permissions of the directories you are planning on uploading the files to, so your user (which is without sudo privileges) could write to those dirs.
I would also read about WinSCP Remote Commands for further detail.

Usually all users will have write access to /tmp.
Place the file to /tmp and then login to putty , then you can sudo and copy the file.

I just wanted to mention for SUSE Enterprise server V15.2 on an EC2 Instance the command to add to winSCP SFTP server commands is :
sudo su -c /usr/lib/ssh/sftp-server
I didn't have enough Reputation points to add a comment to the original answer but I had to fish this out so I wanted to add it.

ssh to FreePBX and run the commands stated below in your terminal:
sudo nano -f /etc/sudoers.d/my_config_file
YourUserName ALL=(ALL) NOPASSWD:ALL
sudo systemctl restart sshd
Winscp:
under session login ==> Advanced ==> SFTP
Change SFTP Server to:
sudo /usr/libexec/openssh/sftp-server

I do have the same issue, and I am not sure whether it is possible or not,
tried the above solutions are not worked for me.
for a workaround, I am going with moving the files to my HOME directory, editing and replacing the files with SSH.

Tagging this answer which helped me, might not answer the actual question
If you are using password instead of private key, please refer to this answer for tested working solution on Ubuntu 16.04.5 and 20.04.1
https://stackoverflow.com/a/65466397/2457076

Related

VScode remote connection error: The process tried to write to a nonexistent pipe

I use vscode with remote-ssh to connect my server, after configuring, I want to connect my host, but it failed, the dialog box display:"could not establish connection to XX, The process tried to write to a nonexistent pipe."
output:
[16:45:20.916] Log Level: 3
[16:45:20.936] remote-ssh#0.49.0
[16:45:20.936] win32 x64
[16:45:20.944] SSH Resolver called for "ssh-remote+aliyun", attempt 1
[16:45:20.945] SSH Resolver called for host: aliyun
[16:45:20.945] Setting up SSH remote "aliyun"
[16:45:21.012] Using commit id "c47d83b293181d9be64f27ff093689e8e7aed054" and quality "stable" for server
[16:45:21.014] Install and start server if needed
[16:45:21.019] Checking ssh with "ssh -V"
[16:45:21.144] > OpenSSH_for_Windows_7.7p1, LibreSSL 2.6.5
[16:45:21.214] Running script with connection command: ssh -T -D 5023 aliyun bash
[16:45:21.221] Terminal shell path: C:\WINDOWS\System32\cmd.exe
[16:45:21.504] >
>
>
> ]0;C:\WINDOWS\System32\cmd.exe
[16:45:21.505] Got some output, clearing connection timeout
[16:45:21.577] >
>
>
>
[16:45:21.592] > Bad owner or permissions on C:\\Users\\DY/.ssh/config
>
[16:45:21.689] > The process tried to write to a nonexistent pipe.
>
[16:45:22.091] "install" terminal command done
[16:45:22.092] Install terminal quit with output: The process tried to write to a nonexistent pipe.
[16:45:22.093] Received install output: The process tried to write to a nonexistent pipe.
[16:45:22.096] Resolver error: The process tried to write to a nonexistent pipe
[16:45:22.107] ------
Add the absolute file path to a custom SSH config file(C:\Users\{USERNAME}\.ssh\config), and my problem is solved.
If you format/re-install Server OS, but use same IP as before,
you may encounter fingerprint mismatched.
You may need to delete old fingerprint in this file:
C:\Users\xxx.ssh\known_host
and old IP in the file:
C:\Users\xxx.ssh\config
Then try to add host again.
What worked for me:
delete ssh config folder both in C:\Program Data\ssh and C:\<user>\.ssh
In VS Code, press F1, choose Remote-SSH: Connect to Host...
Do NOT enter anything in the prompt, but instead choose + Add New SSH Host..
Enter the full ssh command, including the key (in case of Windows,
you may want to enclose the path with double quote mark) ssh -i "C:\path\to\key" user#host. (you need to make sure the key has a limited permission. Remove all inherited permissions, and only give a full control to the owner.)
You will be asked to choose a folder in which a new config file will be created. Choose any of the two options.
There will a prompt notifying that the new config file
has been created. Click connect
At least three things may be happening:
Option 1
The location of your config file is not the absolute location, meaning you are probably using the location of the folder where the config file is.
If that is the case, access your User Settings in VSCode. Scroll to the Extensions>Remote - SSH. And add config at the end of the absolute file path of your custom SSH config file. In Windows, it can be
C:\Users\user\.ssh\config
See image below
Option 2
Authentication problems.
If that is the case, one of the things that may solve is generating new SSH keys.
In Windows, for that, I recommend using MobaXterm.
In MobaXterm, open a new terminal and write
ssh-keygen -b 4096 -t rsa
Then, in the config file, make sure that the IdentityFile points to the location of the key. MobaXterm's home directory, usually, is C:\Users\user\Documents\MobaXterm. If it makes it easy, one can copy/move the keys to C:\Users\user\.ssh and then just add, in the config file, IdentityFile ~/.ssh/KEY_rsa (where KEY_rsa is the name of the [public] key).
Note that if you use PuTTY to generate the keys, on the server OpenSSH authorized_keys file, one doesn't want the public key that one saves, but the one that appears on top (see image bellow):
Option 3
Your config file may be wrong.
The config file tends to look as follows. Double check if the fields have the information needed for the connection to be established.
Host Test # This is the name we want to give the host
User user # This is the username
Hostname blabla.com # This is the hostname
PreferredAuthentications publickey
IdentityFile ~/.ssh/KEY_rsa # This is the location of the key
IdentitiesOnly yes
Port 50 # This varies
What worked for me was to delete all of the contents of folder: C:\Users\MYNAME.ssh That meant to delete both the config file and known-hosts. The config was probably the most important one to delete.
The solution in my case was editing the json settings file for VSC as shown here: https://code.visualstudio.com/docs/remote/troubleshooting#_troubleshooting-hanging-or-failing-connections
In VSC go to File, Preferences, Setting and click on the upper right hand icon (Open Settings, JSON). Add these two lines to settings.json and retry connecting:
"remote.SSH.showLoginTerminal": true,
"remote.SSH.useLocalServer": false
In my case I had another setup:
Git bash in Windows was configured and I am using the ssh.exe provided by this tool
In the "Remote SSH" extension in VSCode, I specified the full path of this ssh.exe
I am using multiple servers (with ProxyJump)
The error message is the same as the OP but in the logs it was written that the ssh config file was not found, where all the folder names was concatenated (because it did not recognize the windows path separator)
Problem: the ssh.exe is using a different path convention thant VSCode. ssh.exe is using the "/c/Users/..." pattern and VSCode is using the "C:\Users..." pattern.
Solution:
Make sure the SSH config is at a standard place (C:\Users\LOGIN\.ssh\config)
Remove the absolute path of the config file in the "Remote SSH" settings in VSCode
VSCode will still be able to access the settings using the standard path, and the ssh.exe configuration will still look at the same standard path so the connexion is working.
Note:
I have the error only when connecting with multiple ssh servers (using ProxyJump). When connecting only to the first server, the solution of #pszrux and this one are both working for me.
This is probably something everyone has tried before looking here, but it worked for me. The server I was trying to ssh into was not responding, leading to the nonexistant pipe error. I rebooted the server and everything worked fine.
OS: windows 10
In my case there were permission issues. Repeatedly changing inheritance in windows did not solve the issue. Finally this worked
change the folder in which the config file is stored.
From C:/users/usr/.ssh/config to D:/config
and changed the config path in vscode remote ssh settings.
This worked for me.
This seems to be a problem with varied causes and corresponding remedies. In my case the problem had to do with the version of ssh I was using. In my Windows path there were two places were an instance of ssh.exe resided:
C:\Program Files (x86)\OpenSSH\bin
C:\WINDOWS\System32\OpenSSH\
After using both paths to set the "Remote.SSH: Path" parameter (which is in "Remote.SSH: Settings" [see here]), i.e. first C:\Program Files (x86)\OpenSSH\bin\ssh.exe and then C:\WINDOWS\System32\OpenSSH\ssh.exe, the problem still persisted.
Then I looked at this and tried the git-provided ssh.exe, which I already had on my system (otherwise, just install git, it's good stuff anyway :) )
Setting the SSH path parameter with that version did the trick for me, i.e. setting path to:
C:\Program Files\Git\usr\bin\ssh.exe
In my case, I did what dalilander said, but instead of deleting the entire '.ssh' folder, I just needed to delete the file 'known_hosts' and then it worked. So the servers I had saved were not deleted.
The path of that folder is C:\Users\yourUsername\.ssh
For Windows:
Adding the escape character before the private key file name & using quotes around the path solved my issue.
//config file
Host 12.12.12.12
HostName 12.12.12.12
IdentityFile "C:\Users\USERNAME/\PRIVATEKEY" <----Note /\
User username
Trying to add the full path in "IdentityFile" made the trick
" IdentityFile C:\Users\xxx.ssh\xxx"
The solution below may be the last resort but it perfectly solved the issue for me in a Windows 10 local machine. I simply delete the known_hosts file under the directory C:\Users\[your-username]\.ssh, relaunch VS Code and reconnect the remote server through Remote Explorer. Everything works normally afterward.
This seems to be a general error when the ssh connection fails for one of a multitude of reasons.
Adding what my issue was, and what helped, because I don't see it in the other answers in here: I had re-installed the box I was connecting to, and with it, reset the key it was using to authenticate. The ssh process tried to connect and failed with the usual "someone might be MITMing you this very moment, the identification changed" error, visible in the VSCode terminal. Solution was to go to my authorized_keys file and remove the offending key.
Obviously only know that if you know for sure why the identification changed, and that it's harmless. Don't actually get MITMed.
I had this problem once.
All you need to do is,
Go to /Users/XXX/.ssh
if you are on the windows, use command : "del /f known_hosts" to delete the known_hosts on the command prompt.
3.Then go to C:\Users\XXX.ssh\config on the vs code( config file )
4.Delete the host and the user if the host that you are trying to connect to is already there.
5.Then try to connect to the new host as usual.This will work.
The problem here could the mismatch of the finger prints once you reinstall the OS o n your host machine.
So to solve this problem by deleting the host that was saved.
once the config file on the vs code is edited it should look like..below picture is to show how the config file should look(after deleting the host saved)
If you're using WSL and might think that you should update ~/.ssh/config, that might not be the case.
Copy the content from ~/.ssh/config
Append it to C:\User\xxx\.ssh\config windows file
Make sure the public/private key is on C:\User\xxx\.ssh\ and is listed in config
Reconnect
Had an existing(working) configuration and had the same error when I added a new one. What worked for me is instead of just adding a new host configuration, I also commented out the first working config. Didn't know what happened but it worked.
In my case this was an offending key in my known_hosts in Windows (vscode on windows, remote developing via ssh on linux).
The error that comes back in vscode is not explaining in any way.
In my case, the path to key file was wrong.
For me, (windows) the permissions on the .pem file were the Critical issue. I had Administrator group only on the pem file and it was not working. I had to explicitly add the Admin user as well (even though admin is of course in administrator group).
In my case, I had no internet connection.
I was connecting to the server via VPN but the remote configuration was incorrect and I couldn't access the server. (DNS related issues) The connection indicator was showing no errors, so I didn't think of that at first.
Oops :)
I really didn't want to delete my C:Users\valo\.ssh\config, so I played a little with the various entries. It turned out that for me the option IdentitiesOnly yes was the problem. I also disabled security inheritance on all key files in the .ssh folder and left only myself, with Full Rights. Here is what my C:Users\valo\.ssh\config looks like now:
CanonicalizeHostname yes
Host aws.r3
HostName 3.31.45.216
ForwardAgent yes
User ubuntu
IdentityFile C:Users\valo\.ssh\u1-client-20210203-090555.pem
# IdentitiesOnly yes # VSCode Remote doesn't like this flag...?
Host github
HostName github.com
User git
IdentityFile ~/.ssh/id_val_ed25519
Host github.vm
HostName github.com
User git
IdentityFile ~/.ssh/id_valo_ed25519
Host *
ForwardAgent yes
AddKeysToAgent yes
LogLevel FATAL
ChallengeResponseAuthentication no
Now I can connect to aws.r3 with VSCode Remote.
A possible solution:
First run cat $HOME/.ssh/id_rsa.pub on your computer. That will get you a key. Save this key somewhere.
Then open this file by running vim $HOME/.ssh/authorized_keys on the computer that you're are ssh'ing to. Then copy the key in a new line of this file and close it by typing :wq.
You are all set.
In my case it was because the name I gave the host in config was myuser#myhostname. So if your config file looks like this:
Host myuser#myhostname
HostName 12.64.88.234
User myuser
Port 22
Try changing it to this:
Host myuser
HostName 12.64.88.234
User myuser
Port 22
Mine was solved by adding ".pem" extension while specifying the private key.
Here's the sample config text for reference.
Host ec2-3-234-8-176.compute-1.amazonaws.com
HostName ec2-3-234-8-176.compute-1.amazonaws.com
IdentityFile ~/.ssh/privatekey.pem
User username
There can be several reasons that have nothing to do with the accepted answer. For me:
Ubuntu 14.04.1 LTS didn't seem to work
Issues with EC2 auth, see pem file config and pem file permissions
And for yet another seeming cause/solution:
Adding the config path explicitly to settings only caused an EISDIR error.
Removing the listing from known_hosts made it need to confirm the fingerprint, but it didn't provide a way to do that. I could see it trying in the terminal output.
The solution a coworker recommended was to delete the vscode-server files from the server. That was the key step in my case. But...
Connecting to the server using another client, I attempted to rm -rf ~/.vscode-server. I could not delete many of the files because "device or resource busy".
That eventually required doing the following:
fuser ~/.vscode-server/[one of the child files ...]. But, you can probably skip this, because mainly I needed to know what to search for. Plus, fuser and lsof were finicky about returning results -- they often just sit waiting for something, I don't know what.
ps -e | grep node since node is the running process using vscode-server files.
For each PID in the list of node processes from step 2, run ps -o user= -p PID, substituting PID with each process PID in turn. This creates a formatted list of the process's associated user.
This is to determine which node processes you own, so you're not even trying to kill anybody else's.
Starting with the lowest node PID I own, run kill -9 PID. You won't need to run this for all PIDs, because killing a lower PID killed a child PID after a few seconds. So keep checking which node processes still exist after killing one: ps -e | grep node
Finally, once all mine are killed, I can rm -rf ~/.vscode-server
Then, I was able to connect via ssh in VS Code again. And, since I left the fingerprint removed from known_hosts, it even asked to confirm the connection to the server (up top, in the command prompt).
Also, for reference, I left the remote-ssh: settings config file entry, mentioned in other solutions, blank.
For reference or further explanation of certain steps above (I don't intend to elaborate more than I did):
rm: cannot remove ‘.vscode-server/bin/xxxxxx/.nfs000000000xxxxxxxxxxxx’: Device or resource busy
How find out which process is using a file in Linux?
https://unix.stackexchange.com/questions/284934/return-owner-of-process-given-pid/284938
In my case it worked when I added the port in my expression, eg ssh user#host-or-ip -p 22. With '22' the default port number, but you can check which port the ssh system is listening on with the sudo service ssh status command.
WSL Related
In my case, the issue was that my keys were set up on Ubuntu on WSL and VS Code was looking for them in Windows. I copied the keys over from the WSL side to Windows and voila! Worked like a charm!
Steps that I took.
Navigated to the /home//.ssh folder in WSL and then entered explorer.exe .
From there, I copied the id_rsa and id_rsa.pub files and pasted them in the windows side, under C:\Users<username>.ssh
Then I tried connecting again from VS Code and it worked perfectly.

Private key to connect to the machine via SSH must be owned by the user running Vagrant

I am trying to follow this vagrant tutorial. I get error after my first two command. I wrote these two command from command line
$ vagrant init hashicorp/precise64
$ vagrant up
After I ran vagrant up command I get this message.
The private key to connect to the machine via SSH must be owned
by the user running Vagrant. This is a strict requirement from
SSH itself. Please fix the following key to be owned by the user
running Vagrant:
/media/bcc/Other/Linux/vagrant3/.vagrant/machines/default/virtualbox/private_key
And then if I run any command I get the same error. Even if I run vagrant ssh I get the same error message. Please help me to fix the problem.
I am on linux mint and using virutal box as well.
Exactly as the error message tells you:
The private key to connect to the machine via SSH must be owned
by the user running Vagrant.
Therefore check permissions of file using
stat /media/bcc/Other/Linux/vagrant3/.vagrant/machines/default/virtualbox/private_key
check what user you are running using
id
or
whoami
and then modify owner of the file:
chown `whoami` /media/bcc/Other/Linux/vagrant3/.vagrant/machines/default/virtualbox/private_key
Note that this might not be possible if your /media/bbc/ is some non-linux filesystem that does not support linux permissions. In that case you should choose more suitable location for you private key.
Jakuje has the correct answer - if the file system you are working on supports changing the owner.
If you are trying to mount the vagrant box off of NTFS, it is not possible to change the owner of the key file.
If you want to mount the file on NTFS and you are running a local instance you can try the following which worked for me:
Vagrant Halt
[remove the vagrant box]
[Add the following line to Vagrantfile]
config.ssh.insert_key=false
[** you may need to remove and clone your project again]
Vagrant Provision
This solution may not be suitable for a live instance - it uses the default insecure ssh key. If you require more security you might be able to find a more palatable soultion here https://www.vagrantup.com/docs/vagrantfile/ssh_settings.html
If you put vagrant data on NTFS you can use this trick to bypass the keyfile ownership/permissions check.
Copy your key file to $HOME/.ssh/ or where-ever on a suitable filesystem where you can set it to the correct ownership and permissions. Then simply create a symlink (!) to it inside the NTFS directory (where you have set $VAGRANT_HOME, for example) like this:
ln -sr $HOME/.ssh/your_key_file your_key_file

copying file from local machine to Ubuntu 12.04 returning permission denied

How to I grant myself permission to transfer a .crt file from my local machine to the aws ubuntu 12.04 server?
I am using the following command from my machine and receiving a permission denied response.
scp -i /Users/me/key_pair.pem /Users/me/ssl-bundle.crt ubuntu#ec2-50-150-63-20.eu-west-1.compute.amazonaws.com:/etc/ssl/certs/
I am following comodo's instruction. Refer to the heading Configure your nginx Virtual Host from the link. I have not set anything up with regards to permission as user. This is a little new to me and will appreciate further sources of information.
I changed the permission of the path on the server and transferred the file!
With reference to File Permissions , I gave the /etc/ssl/certs/ path the "Add other write & execute" permission by this chmod command when ssh'd into the Ubuntu server:
sudo chmod o+wx /etc/ssl/certs/
Then, on my local machine, the following command copied a file on my directory and transferred it to destination:
scp -i /Users/me/key_pair.pem /Users/me/ssl-bundle.crt ubuntu#ec2-50-150-63-20.eu-west-1.compute.amazonaws.com:/etc/ssl/certs/
It is the write permission you need, and depending on your use case, use the appropriate chmod command.
Simplest way to transfer files from local to ec2 (or) ec2 to local by FileZila.
You can connect with your instance by using Filezila, then transfer files from local to server and vice-versa.

Amazon AWS EC2 Instance - Can't connect with SSH

This shouldn't be this hard. I cannot connect to new AWS EC2 instance via SSH clients. I am connecting from a Win 7 box.
Instance OS: Debian 6
AMI: debian-squeeze-i386-20121119-e4554303-3a9d-412e-9604-eae67dde7b76-ami-1977f070.1(ami-a121a6c8)
User: tried root and also ec2-user
Using .pem keypair that AWS generated and I downloaded
Confirmed security group and Key Pair Name on instance
SSH port 22 is OPEN: Nmap says so and Telnet gets a welcome reply
Using 3 different clients: all clients connect ok
PuTTY replies: Server refused our key
MindTerm Java browser add-in replies: Authentication failed, permission denied
Bitvise SSH replies: Attempting 'publickey' auth; auth failed;
Rebooted instance, wash, rinse, repeat...
REBUILT new instance and new keypair, wash, rinse, repeat...
Connecting isn't the issue. Why would the instance not accept the .pem file as the password? Is there an additional step I am missing? I followed EVERY frigging guide I could Google. AWS support is a joke. stackoverflow to the rescue...
TIA.
According to the debian wiki which has documentation on the AMI you are using, the username you need to use to login is 'admin'.
I have had many issues with connecting to EC2 via ssh.
ssh -i the-keypair-filename root#yourdomain.com
- Keypair file must be in same directory.
- I just used terminal to connect.
Make sure you generate or assign the keypair when launching the instance.
Also you can verify the keypair you have set in the AWS Management Console, this is done by selecting the running instance and then looking for "Key Pair Name:".
I hope this is helpful.
My problem was that I didn't add a volume that was expected in the fstab file so the server didn't start fully and the sshd daemon wasn't running.
Check with:
telnet HOST 22
Check the server logs to make sure it starts properly before you waste lots of time like I did.
Amazon Linux AMIs that use ec2-user password are listed at the bottom of this page.
http://aws.amazon.com/amazon-linux-ami/
Check that you are using one of those if trying to use ec2-user, or check the documentation for the AMI you are using.
Teri
Try using the "admin" username and ignore the username suggested by Amazon.
I had the similar problem and I have solved the issue by following approach.
1) Edited the knife.rb file in my chef folder i.e. :\Users\Administrator\chef-starter\chef-repo.chef\knife.rb as bellow:
knife[:aws_access_key_id] = "xxxxxxxxxxxxxxxxxxxx"
knife[:aws_secret_access_key] = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
knife[:region] = 'ap-southeast-1'
knife[:aws_ssh_key_id] = "ChefUser"
knife[:ssh_user]="ec2-user"
In the command prompt, issued the command to create an ec2-server:
knife ec2 server create -r "role[webserver]" --image ami-abcd1234 --flavor t1.micro -G ChefClient -x root -N server01 -i H:\Chef-files\ChefUser.pem
Note that, even though I had given all the details in the knife.rb file, I had to give the .pem file path in coomand line through -i option. That solved my problem.
Check, if the solution of mine helps you.
Cheers,
Chandan
Logging in as "ubuntu" worked for me:
ssh -i private_key.pem ubuntu#myubuntuserver
Hope this helps
--Erin

sshfs with different gid on remote

I don't know how to mount a remote directory
"remote_dir" on computer "remote", having remote gid "wgrp".
Help is welcome.
me#local$ sshfs me#remote:/remote_dir remote_as_wgrp ...wanted_options...
A workaround is to create a new user "me_wgrp" belonging to group "wgrp".
But the problem seems conceptually so simple that I'm sure there is a solution.
Context:
I'm able to connect using ssh on remote compute, and then to change my gid:
me#local$ ssh me#remote
me#remote$ newgrp wgrp
Now I can create files in directories which are only writable by the group "wgrp".
I have tried
sshfs me#remote:/remote_dir remote_as_wgrp -o ssh_command='newgrp wgrp'
but sshfs seems blocked.
Also, if I try
ssh me#remote 'newgrp wgrp'
ssh doesn't give the prompt, but it accepts commands.
You should consider changing the default group on the remote host has newgrp will never return because it opens a new shell.
"newgrp - return you to a prompt of a new shell."
unfortunately it looks like newgrp group, or "newgrp group -" causes sshfs to not work in the newgrp environment. You won't be able to cd into the sshfs directory or ls, basically you'll get a permission denied error (and it's not due to permissions issues). You'll also notice that df no longer shows the sshfs fuse mount.
Ten years after the question was asked, I needed this myself.
I found that it is now possible to add a parameter to sshfs:
sshfs -o sftp_server="sg <group> -c '/usr/lib/misc/sftp-server -u <umask>'" ...
where /usr/lib/misc/sftp-server is the location of sftp-server on the remote system, <group> is the desired group on the remote system, and -u <umask> is an optional way of providing a default umask for the particular sftp-server.