I want to rsync on my local-host via ssh from a remote host without a ssh enabled root account but full access to the whole filesystem.

local-host:

ssh-keygen -t rsa

copy ~/.ssh/id_dsa.pub to remote-host:/home/rsyncuser/.ssh/authorized_keys

rsync files with ssh:

rsync -vaHxr --numeric-ids --delete --rsync-path=rsync_wrapper.sh \
      -e "ssh -c arcfour -o Compression=no -x" \
      rsyncuser@remote-host:REMOTEDIR LOCALDIR

remote-host (source of files to rsync):

groupadd -g 3001 rsyncuser
useradd -u 3001 -g rsyncuser -s /bin/bash -m rsyncuser

/home/rsyncuser/.ssh/authorized_keys:

from="192.168.0.2,",command="/home/rsyncuser/validate-rsync.sh"
 ssh-dss 012345678...

limit access with from (optional).
On sucessfully ssh login command is executed.

/home/rsyncuser/validate-rsync.sh:

#!/bin/sh
case "$SSH_ORIGINAL_COMMAND" in
    *\&*)
        echo “Rejected”
        ;;
    *\;*)
        echo “Rejected”
        ;;
    *\(*)
        echo “Rejected”
        ;;
    *\{*)
        echo “Rejected”
        ;;
    *\<*)
        echo “Rejected”
        ;;
    *\`*)
        echo “Rejected”
        ;;
    rsync\ --server*)
        $SSH_ORIGINAL_COMMAND
        ;;
    *)
        echo "Rejected"
        ;;
esac

/usr/bin/rsync_wrapper.sh:

#!/bin/sh
/usr/bin/sudo /usr/bin/rsync "$@";

/etc/sudoers:

rsyncuser ALL = NOPASSWD: /usr/bin/rsync

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---

dnssec-keygen -a RSAMD5 -b 1024 -n HOST -k -r /dev/urandom home.domain.org

put content of XXX.key into your zonefile

move xxx.key and xxx.private to your client with sftp

/etc/ppp/ip-up.d/ip_update:

#!/bin/sh

TTL=60
SERVER='NAMESERVER'
ZONE='DOMAIN'
HOSTNAME='HOSTNAME.DOMAIN'
KEYFILE='PATH/KEYFILENAME without endings (.key)'

[ -n "$PPP_LOCAL" ] || exit 0

logger "ip_update: Updating dynamic IP $PPP_LOCAL on $SERVER"

RESULT=$(nsupdate -v -k $KEYFILE 2>&1 << EOF
server $SERVER
zone $ZONE
update delete $HOSTNAME A
update add $HOSTNAME $TTL A $PPP_LOCAL
send
EOF)

RC=$?

[ $RC != 0 ] && \
  logger "ip_update $PPP_LOCAL on $SERVER failed ($RC/$RESULT)"

exit $RC

Manual update a zonefile with bind 9.3:

rndc freeze zone
edit the zone
rndc unfreeze zone

References:

secure-ddns-howto
running-a-secure-ddns-service-with-bind

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---

* chrooted
* chaos, internal and external zone
* TSIG updates/zonetransfers for master/slave

apt-get install bind9
/etc/init.d/bind9 stop

/etc/default/bind9: OPTIONS="-u bind -t /var/lib/named"

mkdir -p /var/lib/named/etc
mkdir /var/lib/named/dev
mkdir -p /var/lib/named/var/cache/bind
mkdir -p /var/lib/named/var/run/bind/run
mkdir -p /var/lib/named/var/log
cp /etc/localtime /var/lib/named/etc
mv /etc/bind /var/lib/named/etc
ln -s /var/lib/named/etc/bind /etc/bind
mknod /var/lib/named/dev/null c 1 3
mknod /var/lib/named/dev/random c 1 8
chmod 666 /var/lib/named/dev/null /var/lib/named/dev/random
chown -R bind:bind /var/lib/named/var/*
chown -R bind:bind /var/lib/named/etc/bind

/etc/default/syslogd: SYSLOGD="-a /var/lib/named/dev/log"

dnssec-keygen -a hmac-md5 -b 512 -n host linux.lan

/etc/bind/named.conf on master AND slave:

include "/etc/bind/named.conf.options";
include "/etc/bind/named.conf.local";

/etc/bind/named.conf.options on master AND slave:

acl "internal" { 192.168.0.2; 127.0.0.1; };
acl "trusted" { internal; };

acl "bogon" {
    // Filter out the bogon networks.  These are networks
    // listed by IANA as test, RFC1918, Multicast, experi-
    // mental, etc.  If you see DNS queries or updates with
    // a source address within these networks, this is likely
    // of malicious origin. CAUTION: If you are using RFC1918
    // netblocks on your network, remove those netblocks from
    // this list of blackhole ACLs!
    0.0.0.0/8;
    1.0.0.0/8;
    2.0.0.0/8;
    5.0.0.0/8;
    10.0.0.0/8;
    23.0.0.0/8;
    27.0.0.0/8;
    31.0.0.0/8;
    36.0.0.0/8;
    37.0.0.0/8;
    39.0.0.0/8;
    42.0.0.0/8;
    46.0.0.0/8;
    49.0.0.0/8;
    50.0.0.0/8;
    100.0.0.0/8;
    101.0.0.0/8;
    102.0.0.0/8;
    103.0.0.0/8;
    104.0.0.0/8;
    105.0.0.0/8;
    106.0.0.0/8;
    107.0.0.0/8;
    108.0.0.0/8;
    109.0.0.0/8;
    110.0.0.0/8;
    111.0.0.0/8;
    112.0.0.0/8;
    113.0.0.0/8;
    169.254.0.0/16;
    172.16.0.0/12;
    173.0.0.0/8;
    174.0.0.0/8;
    175.0.0.0/8;
    176.0.0.0/8;
    177.0.0.0/8;
    178.0.0.0/8;
    179.0.0.0/8;
    180.0.0.0/8;
    181.0.0.0/8;
    182.0.0.0/8;
    183.0.0.0/8;
    184.0.0.0/8;
    185.0.0.0/8;
    192.0.2.0/24;
    ! 192.168.0.2; 192.168.0.0/16;
    197.0.0.0/8;
    198.18.0.0/15;
    223.0.0.0/8;
    224.0.0.0/3;
};

logging {
  channel default_syslog {
    // Send most of the named messages to syslog.
    syslog local2;
    severity info;
  };

  channel audit_log {
    // Send the security related messages to a separate file.
    file "/var/log/named.log" versions 5 size 20m;
    severity debug;
    print-time yes;
  };
  category default { default_syslog; };
  category general { default_syslog; };
  category security { audit_log; default_syslog; };
  category config { default_syslog; };
  category resolver { audit_log; };
  category xfer-in { audit_log; };
  category xfer-out { audit_log; };
  category notify { audit_log; };
  category client { audit_log; };
  category network { audit_log; };
  category update { audit_log; };
  category queries { default_syslog; };
  category lame-servers { audit_log; };
};

key "masterslave" {
    algorithm hmac-md5;
    secret "---HASHKEY---";
};

server IP_OF_OTHER_SIDE(/etc/bind/slave) {
    keys {
        masterslave;
    };
};

options {
        directory "/var/cache/bind";
        statistics-file "/var/log/named.stats";
        memstatistics-file "/var/log/named.memstats";
        dump-file "/var/log/named.dump";
        zone-statistics yes;

        // Prevent DoS attacks by generating bogus zone transfer 
        // requests.  This will result in slower updates to the 
        // slave servers (e.g. they will await the poll interval 
        // before checking for updates). 
        notify no;

        // Generate more efficient zone transfers.  This will place
        // multiple DNS records in a DNS message, instead of one per
        // DNS message.
        transfer-format many-answers;

        // Set the maximum zone transfer time to something more
        // reasonable.  In this case, we state that any zone transfer
        // that takes longer than 60 minutes is unlikely to ever
        // complete.  WARNING:  If you have very large zone files,
        // adjust this to fit your requirements.
        max-transfer-time-in 60;

        // We have no dynamic interfaces, so BIND shouldn't need to
        // poll for interface state {UP|DOWN}.
        interface-interval 0;

        allow-transfer { key masterslave; };

// rndc reload won't work because of dynamic updates enabled with
//      allow-update { key masterslave; };

        allow-recursion { trusted; };

        allow-query {
            // Accept queries from our "trusted" ACL.  We will
            // allow anyone to query our master zones below.
            // This prevents us from becoming a free DNS server
            // to the masses.
            trusted;
        };
        allow-query-cache {
             // Accept queries of our cache from our "trusted" ACL.
             trusted;
        };

        blackhole {
             // Deny anything from the bogon networks as
             // detailed in the "bogon" ACL.
             bogon;
        };

        // If there is a firewall between you and nameservers you want
        // to talk to, you might need to uncomment the query-source
        // directive below.  Previous versions of BIND always asked
        // questions using port 53, but BIND 8.1 and later use an unprivileged
        // port by default.

//disabled for random prorts        query-source address * port 53;
        transfer-source * port 53;

        // If your ISP provided one or more IP addresses for stable
        // nameservers, you probably want to use them as forwarders.
        // Uncomment the following block, and insert the addresses replacing
        // the all-0's placeholder.

        forwarders {
                PROVIDER_DNS1;
                PROVIDER_DNS2;
        };

        auth-nxdomain no;    # conform to RFC1035
        listen-on-v6 { none; };
};

master:

/etc/bind/master_linux.lan

$TTL 3D
@ IN SOA ns1.linux.lan. hostmaster.linux.lan. (
           200710131       ; serial, todays date + todays serial #
           8H              ; refresh, seconds
           2H              ; retry, seconds
           4W              ; expire, seconds
           1D )            ; minimum, seconds
;
           TXT  "Linux.LAN, serving YOUR domain :)"
           NS   ns1             ; Inet Address of name server
           NS   ns2
           MX   10 mail        ; Primary Mail Exchanger
localhost  A    127.0.0.1
ns1        A    MASTER_IP
ns2        A    SLAVE_IP
mail       A    MAIL_IP

/etc/bind/named.conf.local

zone "linux.lan" {
    type master;
    file "/etc/bind/master_linux.lan";
};

slave:

/etc/bind/named.conf.local:

zone "linux.lan" {
    type slave;
    file "/etc/bind/slave_linux.lan";
    masters { MASTER_IP; };
    allow-notify { key masterslave; };
};

rndc-confgen > /etc/rndc.conf

copy parts to /etc/bind/named.conf.options on master AND slave:

key "rndc-key" {
    algorithm hmac-md5;
    secret "---HASHKEY---";
};

controls {
    inet 127.0.0.1 port 953
    allow { 127.0.0.1; } keys { "rndc-key"; };
};

master:
/etc/bind/named.conf.local

// Create a view for all clients perusing the CHAOS class.
// We allow internal hosts to query our version number.
// This is a good idea from a support point of view.
view "external-chaos" chaos {
    match-clients { any; };
    recursion no;

    zone "." {
        type hint;
        file "/dev/null";
    };

    zone "bind" {
        type master;
        file "/etc/bind/db.bind";

        allow-query { trusted; };
        allow-transfer { none; };
    };
    allow-recursion { none; };
};

view "internal-in" in {
    // Our internal (trusted) view. We permit the internal networks
    // to freely access this view. We perform recursion for our
    // internal hosts, and retrieve data from the cache for them.

    match-clients { internal; };
    recursion yes;
    additional-from-auth yes;
    additional-from-cache yes;

    include "/etc/bind/zones.rfc1918";

    zone "internal.ournetwork.com" in {
        // Our internal A RR zone. There may be several of these.
        type master;
        file "/etc/bind/db.internal";
    };
    zone "7.7.7.in-addr.arpa" in {
        // Our internal PTR RR zone. Again, there may be several of these.
        type master;
        file "/etc/bind/db.7.7.7";
    };
};

// Create a view for external DNS clients.
view "external-in" in {
    // Our external (untrusted) view. We permit any client to access
    // portions of this view. We do not perform recursion or cache
    // access for hosts using this view.

    match-clients { any; };
    recursion no;
    additional-from-auth no;
    additional-from-cache no;
    allow-recursion { none; };

    include "/etc/bind/zones.rfc1918";
    include "/etc/bind/zones.local";
};

master and slave /etc/bind/zones.local:

// prime the server with knowledge of the root servers
zone "." {
    type hint;
    file "/etc/bind/db.root";
};
// be authoritative for the localhost forward and reverse zones, and for
// broadcast zones as per RFC 1912
zone "localhost" {
    type master;
    file "/etc/bind/db.local";
};
zone "127.in-addr.arpa" {
    type master;
    file "/etc/bind/db.127";
};
zone "0.in-addr.arpa" {
    type master;
    file "/etc/bind/db.0";
};
zone "255.in-addr.arpa" {
    type master;
    file "/etc/bind/db.255";
};

zone "ournetwork.net" in {
    type master;
    file "/etc/bind/db.ournetwork";
    allow-query { any; };
};

zone "8.8.8.in-addr.arpa" in {
    type master;
    file "/etc/bind/db.8.8.8";
    allow-query { any; };
};

master and slave /etc/bind/db.bind:

$TTL    1D 
$ORIGIN bind. 
@       1D      CHAOS   SOA     localhost. root.localhost. ( 
                2001013101      ; serial 
                3H              ; refresh 
                1H              ; retry 
                1W              ; expiry 
                1D )            ; minimum 
        CHAOS NS        localhost. 


version.bind.   CHAOS  TXT "BIND 9.1.3+robhacks" 
authors.bind.   CHAOS  TXT "are better coders than I. :)"

slave:
/etc/bind/named.conf.local

// Create a view for all clients perusing the CHAOS class.
// We allow internal hosts to query our version number.
// This is a good idea from a support point of view.
view "external-chaos" chaos {
    match-clients { any; };
    recursion no;

    zone "." {
        type hint;
        file "/dev/null";
    };

    zone "bind" {
        type master;
        file "/etc/bind/db.bind";

        allow-query { trusted; };
        allow-transfer { none; };
    };
};

// Create a view for external DNS clients.
view "external-in" in {
    // Our external (untrusted) view. We permit any client to access
    // portions of this view. We do not perform recursion or cache
    // access for hosts using this view.

    match-clients { any; };
    recursion no;
    additional-from-auth no;
    additional-from-cache no;

    include "/etc/bind/zones.local";
    include "/etc/bind/zones.rfc1918";

    zone "ournetwork.net" in {
        type slave;
        file "/etc/bind/db.ournetwork";
        allow-query { any; };
        masters { MASTER_IP; };
    };

    zone "8.8.8.in-addr.arpa" in {
        type slave;
        file "/etc/bind/db.8.8.8";
        allow-query { any; };
        masters { MASTER_IP; };
    };
};

References:
secure-bind-template
Bind9 Administration
bin9 hardening

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---

File Permissions

Action	---	r--	-w-	--x	rw-	r-x	-wx	rwx	r-s
read - cat file	no	yes	no	no	yes	yes	no	yes
write - ls /tmp >> file	no	no	yes	no	yes	no	yes	yes
write - ls /tmp > file	no	no	yes	no	yes	no	yes	yes
remove file	yes*	yes*	yes	yes*	yes	yes*	yes	yes
executing a script	no	no	no	no	no	yes	no	yes	yes**

yes*: These files gave a "rm: remove write-protected file 'filename'?" error. Saying "yes" removes these files. Also performing a "rm -rf" file removes the file without any warning. The ability to remove a file is controlled at the directory level.
yes**: execute a file with permission of owner or group

Directory Permissions

Action	---	r--	-w-	--x	rw-	r-x	-wx	rwx
cd into directory	no	no	no	yes	no	yes	yes	yes
ls directory	no	yes*	no	no	yes*	yes	no	yes
file name completion	no	yes	no	no	yes	yes	no	yes
create new file in dir.	no	no	no	no	no	no	yes	yes
read file in dir.	no	no	no	yes	no	yes	yes	yes
modify file in dir.	no	no	no	yes	no	yes	yes	yes
remove files	no	no	no	no	no	no	yes	yes
execute script	no	no	no	yes	no	yes	yes	yes

ls = yes* - Only the files are listed with error. No other file attributes are able to be listed. File name completion works in these cases as well.

t - Save text attribute (sticky bit): The user may delete or modify only those files in the directory that they own or have write permission for (/tmp).

s - Set group ID: files in that directory will have the group ownership as the directory, instead of than the group of the user that created the file


If you want to have full access to a directory with 2 different users in different groups make a new group and add both users.

addgroup newgroup
adduser user1 newgroup
adduser user2 newgroup

chown root:newgroup /directory
chmod 775 /directory

You do not need to use group ID (s-Flag).


You can use these commands to set 755 on directories and 644 on files

find -type f -exec chmod 644 {} \;
find -type d -exec chmod 755 {} \;


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---

apt-get install scponly

gunzip /usr/share/doc/scponly/setup_chroot/setup_chroot.sh.gz
chmod 755 /usr/share/doc/scponly/setup_chroot/setup_chroot.sh
cd /usr/share/doc/scponly/setup_chroot/
./setup_chroot.sh /home/USERNAME USERNAME RELATIVE_WRITEABLE_DIR

cp /dev/null /home/USERNAME/dev

maybe cp /etc/groups /home/USERNAME/etc


HINT: login via ssh is not possible BUT PORTFORWARDING


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---

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