Tag Archives: unix

How to use ipset command on linux to block bulk IPs

ipset is a companion application for the iptables Linux firewall. It allows you to setup rules to quickly and easily block a set of IP addresses, among other things.

Installation

Debian based system

“`# apt install ipset“`

Redhat based system

“`# yum install ipset“`

Blocking a list of network

Start by creating a new “set” of network addresses. This creates a new “hash” set of “net” network addresses named “myset”.

# ipset create myset hash:net

or

# ipset -N myset nethash

Add any IP address that you’d like to block to the set.

# ipset add myset 14.144.0.0/12
# ipset add myset 27.8.0.0/13
# ipset add myset 58.16.0.0/15
# ipset add myset 1.1.1.0/24

Finally, configure iptables to block any address in that set. This command will add a rule to the top of the “INPUT” chain to “-m” match the set named “myset” from ipset (–match-set) when it’s a “src” packet and “DROP”, or block, it.

# iptables -I INPUT -m set --match-set myset src -j DROP

Blocking a list of IP addresses

Start by creating a new “set” of ip addresses. This creates a new “hash” set of “ip” addresses named “myset-ip”.

# ipset create myset-ip hash:ip

or

# ipset -N myset-ip iphash

Add any IP address that you’d like to block to the set.

# ipset add myset-ip 1.1.1.1
# ipset add myset-ip 2.2.2.2

Finally, configure iptables to block any address in that set.

# iptables -I INPUT -m set --match-set myset-ip src -j DROP

Making ipset persistent

The ipset you have created is stored in memory and will be gone after reboot. To make the ipset persistent you have to do the followings:

First save the ipset to /etc/ipset.conf:

# ipset save > /etc/ipset.conf

Then enable ipset.service, which works similarly to iptables.service for restoring iptables rules.

Other Commands

To view the sets:

# ipset list

or

# ipset -L

To delete a set named “myset”:

# ipset destroy myset

or

# ipset -X myset

To delete all sets:

# ipset destroy

How to use rsync with ssh

Rsync is a fast and extraordinarily versatile file copying tool. It can copy locally, to/from another host over any remote shell, or to/from a remote rsync daemon. It offers a large number of options that control every aspect of its behavior and permit very flexible specification of the set of files to be copied. It is famous for its delta-transfer algorithm, which reduces the amount of data sent over the network by sending only the differences between the source files and the existing files in the destination. Rsync is widely used for backups and mirroring and as an improved copy command for everyday use.

Rsync finds files that need to be transferred using a lqquick checkrq algorithm (by default) that looks for files that have changed in size or in last-modified time. Any changes in the other preserved attributes (as requested by options) are made on the destination file directly when the quick check indicates that the file’s data does not need to be updated.

While tar over ssh is ideal for making remote copies of parts of a filesystem, rsync is even better suited for keeping the filesystem in sync between two machines. Typically, tar is used for the initial copy, and rsync is used to pick up whatever has changed since the last copy. This is because tar tends to be faster than rsync when none of the destination files exist, but rsync is much faster than tar when there are only a few differences between the two filesystems.
To run an rsync over ssh, pass it the -e switch, like this:
[root@host]# rsync -ave ssh remote_server:/home/backups/ /home/user/server_backups/
Notice the trailing / on the file spec from the source side  On the source specification, a trailing / tells rsync to copy the contents of the directory, but not the directory itself. To include the directory as the top level of whatever is being copied, leave off the /:
[root@host]# rsync -ave ssh remote_server:/home/backups .
By default, rsync will only copy files and directories, but not remove them from the destination copy when they are removed from the source. To keep the copies exact, include the — delete flag:
[root@host]# rsync -ave ssh -- delete remote_server:~one/reports . 
If you run a command like this in cron, leave off the v switch. This will keep the output quiet (unless rsync has a problem running, in which case you’ll receive an email with the error output).
Using ssh as your transport for rsync traffic has the advantage of encrypting the data over the network and also takes advantage of any trust relationships you already have established using ssh client keys. For keeping large, complex directory structures in sync between two machines (especially when there are only a few differences between them), rsync is a very handy (and fast) tool to have at your disposal.