For this case, conntrack's NAT is enough to alter, tag and handle reply traffic correctly for the connection. One could use both DNAT and SNAT and bind their use together or use a mix of DNAT and adequate routes.
DNAT
This target is only valid in the nat table, in the PREROUTING and
OUTPUT chains, and user-defined chains which are only called from
those chains. It specifies that the destination address of the packet
should be modified (and all future packets in this connection will
also be mangled), and rules should cease being examined. [...]
SNAT
This target is only valid in the nat table, in the POSTROUTING and
INPUT chains, and user-defined chains which are only called from those
chains. It specifies that the source address of the packet should be
modified (and all future packets in this connection will also be
mangled), and rules should cease being examined. [...]
iptables -t nat -A OUTPUT -d 192.168.1.11 -j DNAT --to-destination 192.168.1.10
iptables -t nat -A OUTPUT -d 192.168.1.12 -j DNAT --to-destination 192.168.1.10
iptables -t nat -A OUTPUT -d 192.168.1.13 -j DNAT --to-destination 192.168.1.10
iptables -t nat -A OUTPUT -d 192.168.1.14 -j DNAT --to-destination 192.168.1.10
set the additional source addresses on the client:
ip address add 192.168.1.21/24 dev enp2s0
ip address add 192.168.1.22/24 dev enp2s0
ip address add 192.168.1.23/24 dev enp2s0
ip address add 192.168.1.24/24 dev enp2s0
and either bind the SNAT action conditionally to the initial destination address (before DNAT was done), using an adequate filter with iptables' conntrack match:
iptables -t nat -A POSTROUTING -m conntrack --ctorigdst 192.168.1.11 -j SNAT --to-source 192.168.1.21
iptables -t nat -A POSTROUTING -m conntrack --ctorigdst 192.168.1.12 -j SNAT --to-source 192.168.1.22
iptables -t nat -A POSTROUTING -m conntrack --ctorigdst 192.168.1.13 -j SNAT --to-source 192.168.1.23
iptables -t nat -A POSTROUTING -m conntrack --ctorigdst 192.168.1.14 -j SNAT --to-source 192.168.1.24
or instead of SNAT, much cleaner, use a route hinting directly the intended source address for each destination (even if nat/OUTPUT reroutes, the source address won't change anymore once set). This will allow the client and the ss -tn dport == 48898 to know and display the correct source address. This becomes:
ip route add 192.168.1.11/32 dev enp2s0 src 192.168.1.21
ip route add 192.168.1.12/32 dev enp2s0 src 192.168.1.22
ip route add 192.168.1.13/32 dev enp2s0 src 192.168.1.23
ip route add 192.168.1.14/32 dev enp2s0 src 192.168.1.24
This has to be done like this: one address at a time (DNAT could be simplified/factorized, but not the second part dealing with source).
A connection to the actual 192.168.1.10 address is left unchanged.
